A little back story: I got my first carbine from the Midway batch whenever that was, I think last summer. Its an Inland, 3.07. Interesting mix of parts (type one band, type 2 bolt with type one firing pin and a type of 3 adjustable sight). Anyways, I have had the gun since then, and have shot several thousand rounds out of it. Well, I finally got around to filling out the data sheet and submitting it to Dan Pinto, and he pointed something out to me. I had put that it had the bushing in the rear of the receiver, and he states it should not. Well, upon closer inspection of the " bushing" i discovered I could PUSH the "bushing" using a punch small enough to get into the hole in the back of the receiver. I wondered if I could get it out to see what it was, and I did. I found a ROCK, that I will include a picture of. Now, I have not shot the carbine since removing the rock, or as I first thought, "bushing", but have noticed that the slide seems to not have as much "oomph" when released. 

My question, what in tarnation is the rock doing in it! I am tempted to put it back in. "If it aint broke dont fix it" LOL

I mean, I have shot it (my most reliable shooter with the rock in it), taken it apart and cleaned it dozens and dozens of time (more than necessary) and it has always remained in place until I decided I needed it to come out and see what it really was.

GotSnlB28, yeah, its not a line out, its a rock-out 

If it's a shooter get a Wolf Springs spring kit, I believe about $18.00

Now that you mention it, I did get really jittery after handling it. I will send you a sample for "testing" 

They have both standard and extra power recoil springs. I believe the spring kits are extra power recoil springs and the standard power is sold individually but I'm not sure. I always get the kits as they have all the springs for the rifle for peanuts.

What I can tell you is that I've installed dozens of the extra power recoil springs in 30 Carbines without any issues. I own 2 shooters myself an Inland and a Quality Hardware. All springs and complete bolts replaced, they shoot like it's 1943.

I'm an advocate of that in critical cases of collector grade rifles so the originalspring is there. If the problem is that the spring is a bit short or weak.

However the springs are so inexpensive it makes no sense for a rifle that gets shot regularly, a single recoil spring is $15 and the entire kit with an extra power recoil spring is just $18.

I am shooting competition with a Wolff spring in mine, no problems at all and since I ended up first in the competition last year I can say it works pretty good.

1.  After re-assembling the gun without the rock does it function properly when fired?

2.  If "NO" to the above, does the gun function properly after stretching the spring?

Would be nice to know the answer to both.

I am gonna have to test that theory. It has been raining for the last week, so I am actually busy building an Ark. But, next time I go to shoot I will Pack: 1) The unmarked reproduction Rock 2) My spare Springs 3) a Tape measure to stretch out spring if gun does not function properly. 

Well one of the toughest men known to man Sgt. Maj. Basil Plumly served in WWII, Korea and Vietnam.  I'm sure he wasn't what he used to be after, well neither are the rifles. Fortunately many of the rifles can be brought back to near or to new performance. Damn shame in this day and age that we lose good men.

Look at this forum, go to the web site, if you've got a shooter install an M2 magazine latch and all the updates done during the war. You'll have a wonderful rifle and do the old girls reliability reputation alot of good.

There's plenty of truth in the above statement.  Standard springs have worked for me with 110 grain bulletts, with 13.5 grain to 16.5 grains of LilGun. The extra power springs have been reliable with 14.5 grains to 16.5 grains of LilGun. 

I have never had an issue with an extra power spring with any factory or military 110 grain load.

As a disclaimer: Individual results may and do very.

I have a question when testing do you use modern factory, surplus military or reloaded ammo? Have you chronographed the test ammo? If chronographed how far from the muzzle? 

I ask because if your rifle did not function with a standard power Wolf replacement recoil spring, to me it would suggest other issues. Proper cycling with a military spring to me begs some questions.  Was the replacement unused military surplus? Was it used military? 

The problem I see with the Wolf packaging is that the spring kit I believe only comes with an extra power recoil spring. The standard power spring I believe is only sold by itself. That's a bit confusing. 

Diagnosis is difficult because military surplus ammo is not what it was in 1942, it may have been made in 1942 but today it's 80 years old. Similar can be said for later dated military surplus ammo. Was it ever in spec, if it was has it aged and changed?

The powder used in the original cartridge is no longer available, I've been able to find powders of similar burning rates but never one that I've been satisfied with. I've had better reliability with slower powders, mostly those produced for magnum pistols that operate in the 40,000 to 44,000 PSI range.

I've found that cold weather reliability of my Carbines with surplus ammo has been dubious so I've tested civilian factory ammo and it was not much better. One observation is that the M1 Carbine for me with all ammo is a bit, to more than a bit to out right dirty.

My solution is to use magnum rifle primers for reliable cold weather ignition, Hodgen LilGun in charge weights from 15.5 to 16.5 grains depending on projectile, producing 2050 to 2100 FPS at 10 feet from the muzzle. (Of course those same loads must be hot weather tested for safety.)  An extra power recoil spring to medigate recoil and to improve cold weather cycling, replacing grease and oil with dry lubricants. 

The old greases and oils used for lubrication become liquid with long shot strings and absorb unburnt powder becoming gummy when cooled to down right unusable muck in 5 /10 degree or colder weather.

I've been able to achieve excellent all weather reliability. 

I too liked to find a marginal working carbines, so I could learn what it took to fix them.  I once told all the gunsmiths in town, if they got a carbine in need of repair, I would work on it for nothing except parts if required.  I did get a few calls.  One had a brass ring in the chamber and would not chamber another round, imagine that.  I removed the ring with a 30-06 broken shell extractor.  But of course the owner tried to force in one more.  Way long headspace but too short with the ring.  That was a first for me. 

So I know it can happen.  As far as above, I was shooting Aguila or LC. 

My experiance with my carbines and cold weather makes me wonder if the reported issues in Korean winters was a mix of barely in spec WWII rifles and bad military ammo.

Mine run like rabbits hot or cold.

David - Have you had an opportunity to test carbines with PL Special Lubricating and Preserving Oil or the more recent CLP in extreme cold weather?

I haven't, I'm using a dry moly, when I get back to the house I'll check the brand. I use it on all my autoloaders. 

It is not a preserving treatment,  rifles going to be stored awhile need protection.  However the dry lube really makes long shot string in cold weather and I see no wear that one might expect. 

Yep, if stored in a stable environment I fired 303 British from the Boer War.