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New Carbine, New issue (to me)

Printed From: The Carbine Collector's Club
Category: The Club
Forum Name: Safety/ Accuracy/Shooting/Ammunition/Care and Maintenance
Forum Description: What to Check, Reloading, Tips for Accuracy, Competitive/Recreational Shooting
URL: http://www.uscarbinecal30.com/forum/forum_posts.asp?TID=5795
Printed Date: Jan 21 2022 at 12:26am
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com


Topic: New Carbine, New issue (to me)
Posted By: Rebel92
Subject: New Carbine, New issue (to me)
Date Posted: Oct 17 2021 at 8:33pm
picked up my 2nd carbine Friday. It’s a mid 43 QH, everything down to the sear and firing pin has the appropriate markings on it. Appears to be “as issued” Beautiful gun. Got it cleaned, took the bolt apart (glad I did, I’m pretty sure I am the first person that has ever done so and it was full of thick black goo) and got it lightly greased. Decided to shoot it along with my inland today. Shot 90 rounds from my inland with USGI 30 round mags, 90/90 with no issues. Then pulled out my QH. Used USGI 15 rounders. Out of the 30 rounds I fired from it, I had 4/5 times of it not fully going in to battery, note, it was not firing out of battery. The bolt just would not lock down “fully into battery” Had to drop the mag and pull the op rod back a few times for the extractor to pick it up. This is a new issue to me. Chamber is clean, along with everything else on the firearm. I changed the recoil spring, but that was all I changed out before I took it out to shoot. Any ideas? I had tons of bugs with my inland when I first got it, but I quickly got them sorted out (changed all bolt components and all springs throughout the gun) and is now my most reliable firearm (even more so than my Garand, believe it or not)

Thanks for the suggestions. 



Replies:
Posted By: floydthecat
Date Posted: Oct 18 2021 at 5:24am
Is it not rotating on a loaded round? Will it rotate and lock on an empty chamber? Could be several things at work here, but I’d check head space just because.


Posted By: Rebel92
Date Posted: Oct 18 2021 at 12:57pm
it will rotate and close on a empty chamber, and also with a round. Just about 5 out of 30 rounds the bolt wouldn’t fully rotate. I had to drop the mag and get pull the op rod back so round would eject 


Posted By: floydthecat
Date Posted: Oct 18 2021 at 2:24pm
Is it possible you are running across some ammo with slightly longer cases? I think you gonna have to measure the head space and the brass. If the action happens to be tight and on the border line, it won’t take much longer cases to snag. Check all the bearing and contact sliding surfaces for burrs and rubs. Check to make sure the extractor moves freely and nothings binding.

Run the ammo through by hand and see if you can identify certain rounds that cause the problem. You can swap parts between your carbines to isolate the issue.

Head space might be just fine, but it’s the first thing that should be checked on any new, or new-to-me carbine. 



Posted By: Rebel92
Date Posted: Oct 18 2021 at 3:02pm
thanks. I just have a field gauge (it’s on its way, hasn’t shipped yet) or will I need go/no go? And now that I think about it, I think it ran fine with the Korean surplus, but the Aguila was what gave me issues. I will disassemble and look in bolt locking lugs for burrs, cycle some rounds through it. Would any chamber obstruction cause this? 


Posted By: Matt_X
Date Posted: Oct 18 2021 at 3:06pm
Failure to close would be if the casing is too long, or the headspace is too tight.
The field gage you have coming will indicate if there is too much headspace.

Maybe a drawing would help. Let me look.


Posted By: Rebel92
Date Posted: Oct 18 2021 at 3:08pm
my inland seems to be able to shoot any and all ammo. I have seen where y’all state some carbines are picky about what ammo they like. Very interesting. The bolt on the 43 QH is EM Q




Posted By: Rebel92
Date Posted: Oct 18 2021 at 3:19pm
you want me to do a drawing of it? Or you are doing one?


Posted By: floydthecat
Date Posted: Oct 18 2021 at 4:20pm
With good ammo, it won’t be that picky. Some can be picky about what they will feed, but not usually what they will fire. You don’t report a feeding issue. The possible problem is cases too long. The field gauge will tell you if the action is too long…..not too short. It can pass a field gauge test and not close, but it might be too tight. 

I am going to pm you with the method to measure actual head space to rule that out right off the bat. I have had a carbine that had obviously been shot…a lot, but when I checked the action, it would not close on a go gauge. Previous shooters just had not came across that round that was 1.290 or longer…yet.

It could very well be your Inland eats it and the QH chokes. No two actions are usually exactly the same.


Posted By: Rebel92
Date Posted: Oct 18 2021 at 4:28pm
After I was able to extract the round and load it back into the magazine, it would fire the round that the bolt had just failed to close on. They all fired, eventually. 


Posted By: floydthecat
Date Posted: Oct 18 2021 at 4:35pm
PM sent.

It is possible to maybe “set” the round deeper into the chamber after a couple of bolt-bangs.


Posted By: floydthecat
Date Posted: Oct 18 2021 at 4:49pm
Originally posted by Rebel92 Rebel92 wrote:

After I was able to extract the round and load it back into the magazine, it would fire the round that the bolt had just failed to close on. They all fired, eventually. 

This has me a bit curious…..was the round hard to extract, like it was sticking? Any unfired commercial or reload should not be hard to extract. Tight head space, out of spec brass or sticky chamber will cause that.


Posted By: Matt_X
Date Posted: Oct 18 2021 at 5:09pm
I was going to look for a digitized drawing or photo to mark up.
I thought I had seen one that was suitable.
Sorry I got delayed - had to deal with the seller of my Midway who thought my comment in his CMP feedback thread was unwarrented.  Disapprove 

With Floyd helping you make a check with the real thing, an illustration may not be needed.  
See how that goes. 


Posted By: Rebel92
Date Posted: Oct 18 2021 at 5:13pm
yes, it was difficult to extract. I had to pull the operating rod charging handle back a few times before it would extract the round. It would not extract on the first pull in any of the attempts. 


Posted By: floydthecat
Date Posted: Oct 18 2021 at 5:43pm
I take it the extractor is jumping over the rim? That might need to be looked at as well. Usually one has to almost stomp the charging handle to pull a stuck case and yet the extractor will hang on for dear life. I did have a situation in which the case rim was driving the base back into the extractor arm knocking the claw over the rim, but that was a weird situation. I had to grind a tad off the inside of the extractor arm to make it grab and yank. I will also mention it was a commercial extractor and possibly out of spec to begin with. 


Posted By: Rebel92
Date Posted: Oct 18 2021 at 7:03pm
what do you mean jumping over the rim? 


Posted By: Oldboy53
Date Posted: Oct 18 2021 at 7:17pm
Originally posted by floydthecat floydthecat wrote:

 

I am going to pm you with the method to measure actual head space to rule that out right off the bat. I have had a carbine that had obviously been shot…a lot, but when I checked the action, it would not close on a go gauge. Previous shooters just had not came across that round that was 1.290 or longer…yet.

It could very well be your Inland eats it and the QH chokes. No two actions are usually exactly the same.

I was just reading this post, and remembered that I recently shot up a box of Aguilla. I saw the brass to reload, so went to the shop and pulled out a few pieces. Of the first two I measured, one was 1.280", the other 1.290". I'd say they're not too picky about case length.


-------------
GSMC(SW),USN
2/77-11/89


Posted By: Matt_X
Date Posted: Oct 18 2021 at 8:36pm
Here's a picture I think will be helpful. 

http://www.uscarbinecal30.com/barrels.html" rel="nofollow">
http://www.uscarbinecal30.com/barrels.html" rel="nofollow - from http://www.uscarbinecal30.com/barrels.html

Headspace is the distance from the bolt face to the foward edge of the chamber.
If the cartridge case is too long, then the bolt may not be able to close.
For example if an agulia cartridge has a case 1.293" long, and the headspace is 1.291".

On the other hand if the chamber is a little short, then some cases that are within specification won't allow the bolt to close.

Extractor
painter777 has a great photo on milsurps forum showing the extractor and its plunger.
As the bolt closes on the cartridge, the extractor is pushed back on its spring loaded plunger.
http://www.milsurps.com/showthread.php?t=24758&p=136353&viewfull=1#post136353" rel="nofollow">
http://www.milsurps.com/showthread.php?t=24758&p=136353&viewfull=1#post136353" rel="nofollow - from https://www.milsurps.com/showthread.php?t=24758&p=136353&viewfull=1#post136353


There's an animation showing the extractor snapping over the rim at 4:16 in the training film  digitized and posted here. https://www.milsurps.com/showthread.php?t=17368&p=93030&viewfull=1#post93030" rel="nofollow - https://www.milsurps.com/showthread.php?t=17368&p=93030&viewfull=1#post93030


Posted By: Rebel92
Date Posted: Oct 18 2021 at 8:47pm
I took the bolt apart when I got it on Friday, and it was HORRIBLE. I am 100% the first person to ever take it apart. The extractor was full of black gunk. I soaked it all in hoppes for a day, and cleaned it out with lent free foam q-tip things I have. I did not replace any parts or springs in the bolt, however. I did change the op rod (recoil)spring though. 


Posted By: Rebel92
Date Posted: Oct 18 2021 at 8:48pm
Originally posted by floydthecat floydthecat wrote:

I take it the extractor is jumping over the rim? That might need to be looked at as well. Usually one has to almost stomp the charging handle to pull a stuck case and yet the extractor will hang on for dear life. I did have a situation in which the case rim was driving the base back into the extractor arm knocking the claw over the rim, but that was a weird situation. I had to grind a tad off the inside of the extractor arm to make it grab and yank. I will also mention it was a commercial extractor and possibly out of spec to begin with. 

Are you saying it could be a burr on my extractor or an issue with the extractor?


Posted By: Rebel92
Date Posted: Oct 18 2021 at 9:02pm
ok, I got it to do it with Korean army surplus cycling in my home




Posted By: W5USMC
Date Posted: Oct 18 2021 at 9:42pm
Swap bolts with your other carbine and see if it still does it. Is your extractor plunger installed correctly? Is your chamber pitted?

-------------
Wayne
USMC Retired
NRA Life Member


Posted By: Rebel92
Date Posted: Oct 18 2021 at 9:54pm


Posted By: Rebel92
Date Posted: Oct 18 2021 at 9:55pm
it should be. The slot on the plunger fits in the slot on the extractor. Let me know if I have been doing it wrong all along. I don’t think I have tho 


Posted By: Rebel92
Date Posted: Oct 18 2021 at 9:58pm


Posted By: W5USMC
Date Posted: Oct 18 2021 at 10:01pm
That is correct, can you pry up on the extractor lip, it should move and the plunger should move inward.

-------------
Wayne
USMC Retired
NRA Life Member


Posted By: Rebel92
Date Posted: Oct 18 2021 at 10:12pm
WHAT IS GOING ON THIS JUST HAPPENED WHILE CYCLING MY ROUNDS ARMSCOR AMMO






Posted By: Rebel92
Date Posted: Oct 18 2021 at 10:14pm
yes. I tried the spare bolt I just got, and I cycled the rounds fine until I literally had a bullet come unseated. See the picture I just posted 


Posted By: Rebel92
Date Posted: Oct 18 2021 at 10:25pm
chamber is not pitted, bore is like a mirror. Tried with new bolt. Went well until I had a bullet come unseated. See my picture. Feel free to share my plight with other experts. I am at a loss been around firearms my hole (short) life. Never seen that. Or heard of it. These aren’t reloads. Ordered from Palmetto (armscor) a couple months ago. I cycled my Korean surplus with my spare bolt through it fine. Had issues with the original quality hardware bolt. 


Posted By: floydthecat
Date Posted: Oct 19 2021 at 6:05am
It would be understandable for the spare bolt to run, it might be slightly shorter lengthening head space. If one cycles a round long enough, it’s possible to pull the bullet if it is being slightly grabbed by the rifling, or rough handled. Case tension can loosen by handling the round.

I know you are gathering the stuff you need to make some measurements. Discovering what’s going on with head space and brass length will help us determine what’s going on here.

I think Wayne was inquisitive about the extractor as I was. If it is somehow not installed properly, it might interfere with closing by not jumping over the rim. If it can be manipulated freely with a punch or screwdriver….should be good. Jumping back off the rim as you tried to extract it can be caused by the round being driven into the chamber (tight head space). I know I sound like a broken record, but checking that is the first step.


Posted By: Rebel92
Date Posted: Oct 19 2021 at 8:28am
ok thanks Floyd. My caliper comes in tomorrow. Will check it out tomorrow and report back. Thanks y’all, for helpin a rookie out


Posted By: Rebel92
Date Posted: Oct 19 2021 at 8:35am
yes I can pry the extractor , but it is quite stiff compared to my inland bolt. Should I change the extractor spring out?


Posted By: floydthecat
Date Posted: Oct 19 2021 at 8:41am
Sometimes it might feel like we beat things to death and drone-on, but in the long run….others that watch learn in the process. The carbine is a wonderful little piece of machinery. Most problems can be solved by the knowledgeable forum members here that have been there and done that. I am confident this one will be corrected too.


Posted By: floydthecat
Date Posted: Oct 19 2021 at 8:46am
Originally posted by Rebel92 Rebel92 wrote:

yes I can pry the extractor , but it is quite stiff compared to my inland bolt. Should I change the extractor spring out?

You can measure your spring length. Anything down around .380 can be too weak and much above .420 could be too stiff. There could be some difference in the “feel”, but the test is, does it work and if it does, spring length won’t matter. Lets solve one problem at a time.😁


Posted By: Matt_X
Date Posted: Oct 19 2021 at 9:22am
A slight aside.  I bought dummy rounds (aka snap caps) to cycle and dry fire practice (has a rubber primer).  After a number of cycles the bullets started to  get pulled out.  I noticed it first when they didn't easily load and unload from the magazine.  Being empty cartidges I just squeezed them back in with a vise.  Obviously or maybe not so obviously don't do that with a live round.

My points are that its not unusual for the bullet to get yanked a little when cycled without firing. 
And if you want rounds for cycling there are people out there selling dymmy rounds and snap caps.
The dummy rounds made for the US Military may be more durable ???? in terms of cycling without pulling apart.  


Posted By: floydthecat
Date Posted: Oct 19 2021 at 10:06am
Another aside….the ogive of the bullet can vary among manufactures. Some broader nosed projectiles might be more apt to stick in the rifling. Some shooters have reported their carbine will only feed USGI spec ammo. 


Posted By: Rebel92
Date Posted: Oct 19 2021 at 10:27am
Yessir, I hope so. I would like to be able to solve this while maintaining the bolt since it is the correct one for the model. But If i cant shoot it, I will obviously swap bolts. If headspace is indeed the issue, what (if anything) can be done? 


Posted By: Rebel92
Date Posted: Oct 19 2021 at 10:29am
Originally posted by floydthecat floydthecat wrote:

Another aside….the ogive of the bullet can vary among manufactures. Some broader nosed projectiles might be more apt to stick in the rifling. Some shooters have reported their carbine will only feed USGI spec ammo. 

I had issues with the Aguila, and then Armscor. I thought it was all aquila, but then realized the other mag was loaded with armscor. After i noticed that ( I was out of the aguila), i looked through the remaining armscor rounds I had and sure enough, almost every single round has the bullet seated at different depths and the projectiles are 100% more round/fat than the military surplus I compared it against. The rabbit hole just keeps getting deeper for me. 


Posted By: Rebel92
Date Posted: Oct 19 2021 at 10:33am
well that makes me feel better. I have cycled plenty of rounds (safely, of course) and hadn't had the issue. But I primarily shoot usgi/korean surplus ammo, but decided I would shoot up all the commercial ammo I have first (other than my softpoints) and hold on to the surplus for a rainy day. It seems the only commercial ammo that has not given me any issues in the short time (about 7/8 months) I have been shooting and learning about carbines is the Freedom Munitions/LAX ammo. But I will check my firearms headspace first before I arrive at my conclusion. 

Something else that makes me think the firearm may have a bug in it is that my inland shoots the commercial ammo just fine. I am confident with all of your help I can get this figured out.

The bugs I had with my inland when I first got it were Failure to Feeds, and I was able to figure that one out on my own. This one is a new one to me. 


Posted By: Rebel92
Date Posted: Oct 19 2021 at 2:55pm
If it makes any difference, this is a quality hardware, therefore it has the spring tube receiver. 


Posted By: floydthecat
Date Posted: Oct 19 2021 at 4:15pm
Originally posted by Rebel92 Rebel92 wrote:

If it makes any difference, this is a quality hardware, therefore it has the spring tube receiver. 

Shouldn’t matter.

You mentioned above what might could be done if in fact you have a head space issue. A couple of physical things and one maybe a mental thing.

Find a shorter bolt. That will get difficult finding a bolt with the correct makers mark and guessing if it will be shorter when you do. Obviously, you can get any primes bolt that will work and use it as a shooter. The correct Quality can be for looking it.

Have the chamber finish-reamed for your Quality bolt.

The mental option. Find and shoot ammo that you know it will shoot and never use any that you have not checked. Most commercial that I have checked will fall around 1.285-87. The outliers are surely out there. You can learn to measure the cases on unfired brass close enough to be comfortable with doing it.

So…there you go. A replacement bolt, a trip to a Smith (or friend) you can trust to touch-up the chamber, or just watch your ammo.


Posted By: W5USMC
Date Posted: Oct 19 2021 at 4:47pm
What barrel is on your QHMC? Does it appear to be original to the receiver? 

-------------
Wayne
USMC Retired
NRA Life Member


Posted By: Rebel92
Date Posted: Oct 19 2021 at 5:15pm
Yes, it appears to be original to the receiver. It is an undated Rock-Ola, and the finish matches the rest of the gun. Serial number is 1,881,065


Posted By: W5USMC
Date Posted: Oct 19 2021 at 5:35pm
If the barrel is in fact original to that receiver then I would find it very hard to believe that the chamber is short. Take that QHMC bolt apart again and make sure that there is nothing stuck in the extractor plunger spring hole, (like a piece of broken spring).  Don't like the idea of reaming the chamber unless it is truly necessary and you should not have to unless that barrel has been replaced.

-------------
Wayne
USMC Retired
NRA Life Member


Posted By: Rebel92
Date Posted: Oct 19 2021 at 5:53pm
Okay, I will take it apart when I get back home. I thought I was careful to check for that (I have heard of extractor springs being broke off before) but I will get my headlamp and my jewelers screwdriver to get down in the hole and see if something is there. The bolt is marked "EM-Q" and an undated Rock-Ola barrel are what should be there (based on my research). I guess someone could have tried to "correct it", but i know for a fact that it has been in that configuration since at least 1985 (when I bought it, it came with the original receipt, and it had the spec's on the receipt) and I would doubt someone going through that trouble way back then, but what do I know 


Posted By: floydthecat
Date Posted: Oct 19 2021 at 6:27pm
If something is stuck in the plunger spring pocket, it would have been difficult getting a spec spring and plunger to fit I think, but I sure don’t disagree in checking. Take a twist drill and ream the pocket out by hand. While you have the bolt gutted, close a naked bolt by hand on some of that suspect ammo. This takes any extractor issues out of the picture.


Posted By: bonnie
Date Posted: Oct 19 2021 at 7:10pm
Originally posted by Rebel92 Rebel92 wrote:

I took the bolt apart when I got it on Friday, and it was HORRIBLE. I am 100% the first person to ever take it apart. The extractor was full of black gunk. I soaked it all in hoppes for a day, and cleaned it out with lent free foam q-tip things I have. I did not replace any parts or springs in the bolt, however. I did change the op rod (recoil)spring though. 


If your bolt was that grungy.....

Clean the chamber with a 9mm bore brush also. A short, flexible rod with the brush from the receiver into the chamber works best.


Posted By: Rebel92
Date Posted: Oct 19 2021 at 7:31pm
well nothing I can see in the extractor spring hole :(


Posted By: Rebel92
Date Posted: Oct 19 2021 at 7:33pm
no cigar 


Posted By: floydthecat
Date Posted: Oct 19 2021 at 8:27pm
I know you say the chamber is clean, but I had a problem with a sticky one. I used some fine grain lapping compound on a patch using a drill motor polished the rascal to a mirror finish. It seriously helped.


Posted By: Rebel92
Date Posted: Oct 19 2021 at 8:53pm
https://www.oreillyauto.com/detail/c/versachem/chemicals---fluids/maintenance-chemicals/grease---lube/valve-grinding-compound/6dcbc935f700/versachem-valve-grinding-compound/ver0/13209" rel="nofollow -  https://www.oreillyauto.com/detail/c/versachem/chemicals---fluids/maintenance-chemicals/grease---lube/valve-grinding-compound/6dcbc935f700/versachem-valve-grinding-compound/ver0/13209

So you took something like this, (the fine grain tube in it) put it on a patch, put on a drill and scrubbed the chamber with it? 

This is uncharted territory for me, so I’m making sure I don’t do anything stupid. 

For good measure, I have my bolt soaking in hoppes tonight as I have my caliper coming tomorrow. 


Posted By: Rebel92
Date Posted: Oct 19 2021 at 8:55pm
my field gauge hasn’t even shipped yet… but if my chamber is to “tight” that won’t help me figure anything out anyways will it?


Posted By: Rebel92
Date Posted: Oct 19 2021 at 9:01pm
https://www.amazon.com/Loctite-1777012-Grinding-Lapping-Compound/dp/B00O542WDK/ref=asc_df_B00O542WDK?tag=bngsmtphsnus-20&linkCode=df0&hvadid=80470624769032&hvnetw=s&hvqmt=e&hvbmt=be&hvdev=m&hvlocint=&hvlocphy=&hvtargid=pla-4584070153585060&psc=1" rel="nofollow -  https://www.amazon.com/Loctite-1777012-Grinding-Lapping-Compound/dp/B00O542WDK/ref=asc_df_B00O542WDK?tag=bngsmtphsnus-20&linkCode=df0&hvadid=80470624769032&hvnetw=s&hvqmt=e&hvbmt=be&hvdev=m&hvlocint=&hvlocphy=&hvtargid=pla-4584070153585060&psc=1


Posted By: floydthecat
Date Posted: Oct 20 2021 at 6:14am
I use the product you listed above from O’Riley. A little goes a long way, so you don’t need the tub. Don’t get carried away, all you want to do is shine it.

I still probably wouldn’t do anything until I head space it though.

The field gauge is only going to tell you if the head space is too long. In this case, we are dealing with potential short head space, so not having the field gauge is no issue at this point.


Posted By: 35 Whelen
Date Posted: Oct 20 2021 at 7:15am
Disassemble the bolt then put the bare bolt back in the rifle, then try the same cycling with ammunition. If it works, then there may be a problem with the extractor, if not, then you've eliminated one thing, at least.


Posted By: floydthecat
Date Posted: Oct 20 2021 at 8:16am
Tricky and suspicious things happen in a guns action, some of which is impossible to see and sometimes leaves one scratching their head.

OP has indicated issues with bolt rotation and extraction. The two issues are surely connected. I have had experience with this very problem. Be it a tight/fouled chamber, short head space or long ammo cases…..if the round is not fully seating in the chamber and offering a minimal amount of clearance between the bolt face and the cartridge base….extraction issues will follow. I think when head space issues are corrected, be it a chamber issue or bolt/cartridge length, the extraction issue will go away.

You can take the assembled bolt in your hand and test the operation of the extractor by hand with a piece of brass and have it function flawlessly. Shoot it in a gun and funny things you cannot see or detect take place.


Posted By: Rebel92
Date Posted: Oct 20 2021 at 8:31am
today is the day I find out. 


Posted By: Matt_X
Date Posted: Oct 20 2021 at 9:01am
I think the idea of checking with an empty brass is a good way to be eliminate the possibility it relates to the bore.   I bring this up because of hte bullet being pulled off the case.  In fact that's the one of the cases I'd measure and run through the action to see if it sticks.


Posted By: New2brass
Date Posted: Oct 20 2021 at 9:15am
I would think the bullet head coming out would be the rifling and not the chamber.
Recently someone had mentioned that the Winchester dummy rounds could leave the bullet head in the chamber.

There was also a discussion somewhere how the carbine .30 cal is not crimped, so there would be very little grab to retain the bullet head.


-------------
http://www.uscarbinecal30.com/forum/club-assistance-saginaw-receivers_topic4716.html" rel="nofollow - Club Survey Saginaw Receivers


Posted By: Rebel92
Date Posted: Oct 20 2021 at 9:23am
I did notice some very light scratches right after the chamber, right where the rifling begins. 


Posted By: Matt_X
Date Posted: Oct 20 2021 at 10:08am
Dan,
Were you thinking of this thread http://www.uscarbinecal30.com/forum/my-1-9-mil-npm-from-mway-w-free-bullet_topic5543.html" rel="nofollow - My Midway...w/ free bullet ?
Redtail wrote "It wasn't in more than 3/4-1 inch in, just to the the rifling as you can see..."
By  1" was he was describing the chamber length?  That was what I  guessing.
The dummy bullets I mention there were recently made and sold on e-bay.  None show rifling impressions but did start to pull out over repeated use.
(The photo I posted later in the thread is a mystery bullet that was in my house growing up.  IIRC it was in an abelone shell along with matchbooks.  Not even sure its .30 carbine although it has 4 grooves so I think its likely.)

Since then I've received some 1943-44 WRA dummy cartridges with the tin coated bullets.    http://www.uscarbinecal30.com/forum/ammunition-types-historical_topic5767.html" rel="nofollow - http://www.uscarbinecal30.com/forum/ammunition-types-historical_topic5767.html
I have only cycled them through once.




Posted By: floydthecat
Date Posted: Oct 20 2021 at 11:48am
In any event, the round designed to fit the caliber should drop-in and freely pull-out. If it has to be pressed-in or prized-out, something is wrong with the chamber or the ammo. It’s called the “plunk test”.


Posted By: Rebel92
Date Posted: Oct 20 2021 at 10:23pm
sent you a PM


Posted By: floydthecat
Date Posted: Oct 21 2021 at 6:32am
For the sake of others following here, lets share what you have discovered. Indications are that you have a 1.291-1.292 with the QH bolt and maybe a bit tighter with a SG bolt, but it does close. Slight pressure is subjective, it can very between a lumberjack and a surgeon, but indications are that you are within specs. A go gauge is 1.290 and your action should surely close on that.

You have both an envious situation yet perilous. As long as you don’t exceed normal brass lengths, no problem. Where you will possibly get into difficulty is out-of-spec brass or varying projectile shapes. It’s been documented that some chambers don’t like some profiles. A round longer than the action likes, or a profile that contacts the rifling could cause issues. You have pulled at least one bullet, which indicates the latter might be in play.

I have lost track whether this is a “correct” carbine or not. If it is original, I would clean it up, leave it alone and shoot my shooter. If it is a shooter, I’d find another bolt that was shorter for that just-in-case situation, or be forced to measure the ammo that I fired in it. A chamber can get a little grungy, a case can be out-of-spec or a bullet profile it doesn’t like can show up. You might find yourself looking at the bolt lugs to make sure it rotated. I have an SG that measures 1.291. It’s a shooter and I found a bolt that head spaces 1.293, which makes me more comfortable.

PS: I’d try to cancel the order for the field gauge, you won’t need it unless you plan to be evaluating carbines in the future for long head space.😁


Posted By: Rebel92
Date Posted: Oct 21 2021 at 9:16am
Yes, it is a correct QH I will post pictures elsewhere on the forum in just a minute. ... It is not my shooter, but I would like to be able to shoot it occasionally. Would you recommend it I only shoot USGI surplus ammo, or is it just as likely to be out of spec as the commercial ammo? And would you recommend I pull a few bullets from commercial and or usgi/korean surplus? 


Posted By: floydthecat
Date Posted: Oct 21 2021 at 9:43am
A matter of personal choice. Personally, I won’t tolerate a gun that doesn’t shoot off-the-shelf ammo that is suppose to be designed to shoot in it, but we do know some carbines can have issues with some profiles. You can pick and chose ammo that for sure works, or go with a shorter bolt for longer head space that will likely shoot about everything. You can get a case gauge off epay for about $20, but that doesn’t catch the off-spec bullet profiles or rounds possibly exceeding overall spec length. I guess you have to determine just what brand of ammo might be problematic and avoid it. Keep an eye on the bolt. If it doesn’t rotate it shouldn’t fire, but it might and the least damage will be a cracked right bolt lug.

The carbine is most certainly in spec. Some commercial ammo might not be.


Posted By: Rebel92
Date Posted: Oct 21 2021 at 9:46am
Okay, so essentially just shoot milsurp from the QHMC? I am okay with that, as I have acquired a lot of that. I only buy commercial ammo when I find it cheap (whatever that means in todays market). And I will be reloading my brass soon(ish)


Posted By: Rebel92
Date Posted: Oct 21 2021 at 9:48am
and is the fine lapping compound un-necessary now?


Posted By: floydthecat
Date Posted: Oct 21 2021 at 9:54am
Originally posted by Rebel92 Rebel92 wrote:

and is the fine lapping compound un-necessary now?

If you think the chamber is clean and a spec round passes the plunk test and you don’t have sticky-extraction, I don’t think polishing is necessary.


Posted By: Rebel92
Date Posted: Oct 21 2021 at 9:57am
the plunk test would be done with a functional round? And just drop it in, and see how easy it pulls out?


Posted By: floydthecat
Date Posted: Oct 21 2021 at 10:14am
Originally posted by Rebel92 Rebel92 wrote:

the plunk test would be done with a functional round? And just drop it in, and see how easy it pulls out?

Correct. See if it drops in and bottoms without forcing it. Maybe have to use a finger-nail to pull it out. I push on it to insure seating, but it should slide out easily.


Posted By: Rebel92
Date Posted: Oct 21 2021 at 10:19am
Something else I guess I had never noticed or thought to ask, does this look right? How far my homemade headspace gauge is coming out of the chamber? 




Posted By: Matt_X
Date Posted: Oct 21 2021 at 12:34pm
Basically yes.
Take a look at the cutaway from the club's webpages I posted earlier.
This one.

The lower arrow points the end of the barrel.
The entire rim of the cartridge is outisde the barrel. 
The rim of the bolt  is shown touching the barrel face although I suspect that's a slight clearance fit or else the bolt wouldn't rotate in as easily as it does.

There maybe subtlties I'm missing.



Posted By: floydthecat
Date Posted: Oct 21 2021 at 12:40pm
Yep….hard to distinguish any difference in thousandths, but looks good.

I don’t think the rim is tapered that aggressively on the base in real-world ammo. Looked at that picture before and never noticed that.


Posted By: Rebel92
Date Posted: Oct 21 2021 at 2:36pm
Well, FloydTheCat Did it again (Genius). Headspace came back and was within speck. Tried the Plunk test on both carbines with Korean Surplus and Armscor ammo.

On my inland, which shoots anything I give it, had both the Korean Surplus and Armscor seat and come out easily. (no surprise, have no issues at all with it anymore)

Moved on to my QH (one with the perceived "issues"), and the Korean seated and slid out with no pressure with my tweezers. 

Next, I plunked the Armscor in it. I had to squeeze and pull with my tweezers to get the Armscorp out of the chamber. IT WAS TIGHT.  So, I guess it really was the ammunition and how tight my chamber is. Very interesting results, but pleased that's all it is. Luckily I only have a few hundred rounds of armscor, which will be fed to my inland to conquer the turtles taking over my pond! 


Posted By: New2brass
Date Posted: Oct 21 2021 at 2:48pm
what is the serial number range of the two carbines?
barrel dates if present


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Posted By: Rebel92
Date Posted: Oct 21 2021 at 2:54pm
Inland has barrel date of 11-43 serial number is 3072253

QHMC has an undated Rock-Ola Barrel, Serial number is 1881065



Posted By: New2brass
Date Posted: Oct 21 2021 at 4:01pm
OK, so the Inland would have the late chamber.
According to CCNL 334-3 we have seen in the serial range of 1875-1890 RO undated barrels, BA-9-43, Underwood 8-43 and RO 6-43

In another thread we were discussing the change in ammo case profile and chamber profile being changed in June of 1943.
http://www.uscarbinecal30.com/forum/may-1944-ammo-test_topic5731.html#45400" rel="nofollow - http://www.uscarbinecal30.com/forum/may-1944-ammo-test_topic5731.html#45400

Rockola stopped dating barrels in 6-43 and this may not be a coincidence.
I am wondering if your undated RO barrel may have been one of the first undated and somehow has the earlier profile which is causing the chamber to catch the later ammo a little but more?

Only real way to find out is to slug the barrel. I am sure others can explain how and where to get he metal to do so, if you were interested in doing it.

Basically I believe they found the later profile case should work in all carbines, but earlier cases would have malfunctions in later carbines.



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Posted By: floydthecat
Date Posted: Oct 21 2021 at 4:05pm
Gotta luv the carbine world! A mystery at every turn, which makes it all interesting and fun.😁


Posted By: floydthecat
Date Posted: Oct 22 2021 at 5:31am
Originally posted by New2brass New2brass wrote:

Basically I believe they found the later profile case should work in all carbines, but earlier cases would have malfunctions in later carbines.

Armscor would be of the later design….I assume. Just guessing here and assuming no commercial manufacturers were producing ammo at that time, thus all commercial ammo would be of the later design and should fit either chamber? I think this is a case of the Armscor bullet profile just not liking the chamber in this carbine. It being a very little-fired and fresh chamber, the crisp rifling in the throat is grabbing it. I bet after some firing and wear, won’t be a problem at all.


Posted By: New2brass
Date Posted: Oct 22 2021 at 10:19am
Originally posted by floydthecat floydthecat wrote:

Originally posted by New2brass New2brass wrote:

Basically I believe they found the later profile case should work in all carbines, but earlier cases would have malfunctions in later carbines.

Armscor would be of the later design….I assume. Just guessing here and assuming no commercial manufacturers were producing ammo at that time, thus all commercial ammo would be of the later design and should fit either chamber? I think this is a case of the Armscor bullet profile just not liking the chamber in this carbine. It being a very little-fired and fresh chamber, the crisp rifling in the throat is grabbing it. I bet after some firing and wear, won’t be a problem at all.


Any .30 carbine ammo made after the specification change should have been to new standards.
Ordnance was reaching out to all ammo manufacturers for propellant and primer types to fine tune the .30 carbine.

Fast forward to today, manufacturing has changed and are the commercial manufacturers holding tolerances or making their product "good enough?"

I would default to you on what ammo is better digested than other ammo companies


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Posted By: floydthecat
Date Posted: Oct 22 2021 at 10:53am
Originally posted by New2brass New2brass wrote:

manufacturing has changed and are the commercial manufacturers holding tolerances or making their product "good enough?"


That's for sure. Armscor on the right. I personally have never had issues with it and it feeds and bangs in anything I shoot, but it's obvious the profile differs. I have noticed they seem to seat the bullets a little deeper, closer to 1.65-.66 on average.




Posted By: floydthecat
Date Posted: Oct 22 2021 at 11:34am
I hate to belabor the point, but old bored people like me have to pass the time of day doing something. I have looked again at the thread concerning the chamber/ammo revision. One thing they did was to reduce the lead in the chamber, the space between the case-mouth and the rifling. This would in effect require a different taper of the projectile in order for the bullet nose not to solidly contact the rifling. It almost seems like the Armscor was designed with the old chamber in mind?  


Posted By: DonFlynn
Date Posted: Oct 22 2021 at 11:47am
My 2 bits, if the OP can find any of the Korean surplus in stock try that. 2nd choice would be trying S&B, I've never had any trouble with that any carbine I've run it on. I've even been saving a case of 500 of that to use to break in a new Fulton Armory carbine I have on order due soon 


Posted By: W5USMC
Date Posted: Oct 22 2021 at 12:27pm
Don, the OP has Korean surplus ammo which he has stated works fine, he is only having his issues with the Armscor.

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Wayne
USMC Retired
NRA Life Member


Posted By: DonFlynn
Date Posted: Oct 22 2021 at 2:55pm
Originally posted by W5USMC W5USMC wrote:

Don, the OP has Korean surplus ammo which he has stated works fine, he is only having his issues with the Armscor.

Opps, missed that. Strange then, I've run 1000's of rounds of Armscor the past couple years (I found a deal on it before the current panic) and the only carbine it gave me issues with was my Plainfield before I swapped springs in the bolt


Posted By: Rebel92
Date Posted: Oct 27 2021 at 6:00pm
Thanks everyone. I think I got it remedied (just by feeding it mil-surp). Have only had a chance to dry cycle the ammo, haven’t been able to send any turtles to their meet their maker yet but will one day this week

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"If everyone is thinking alike then somebody isn't thinking."

Gen. George Patton



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