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Milsurp OAL vs SAAMI OAL
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Matt_X View Drop Down
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    Posted: Jul 27 2022 at 1:14pm
1971 Lake City  50-205   From an original box that was a bit beat up.

Overall length 1.676" + .004" /- .003"
Measured with vernier caliper.
Sample size of 10
Standard deviation .0024"

Average case length 1.283"
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Originally posted by Sawbones Sawbones wrote:

...the milsurp stuff, namely  Evansville Cartridge Company 1944 and Lake City 1952 all measured 1.665 +/- 0.002"


I bought an unopened box of M13 Dummy cartridges made by Winchester Repeating Arms Co. lot 22038.   Opening the box they are all stamped WRA * 44.

Overall length 1.675" + .001" /- .002"
Measured with vernier caliper.
Sample size of 10
Standard deviation .0011"

So far the military contract ammo is all within the drawing specs of 1.660 to 1.680"

Case length measurements average 1.285"  with std dev of .00158"
Measuring the case length with the bullet installed probably reduces the consistance of my masurements using a caliper.
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So your carbine was made early to mid 1943.
In the links below we discussed that the barrel chamber was changed in June of 1943. Basically from that point on all ammunition on hand was reserved for stateside and the new profile ammunition went to the theaters of operation.
The new ammo worked in early and late barrels, but the old ammunition may have problems in the new barrels.

In reality any new made ammunition should be to the latest standards, but if not held to the standard it is possible that there may be an issue in an early barrel.
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So sorry for the late response.  For reason unknown the Forum is not alerting me of replies.
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I think this one was a Closet Queen.  Obviously sat in a closet somewhere since 1943 birth. Stock is beautiful walnut w/ few handling marks and all working parts show little wear.
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Dan Pinto, Photo Editor

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@Sawbones, What carbine and serial range are you using?
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Originally posted by Sawbones Sawbones wrote:

SAAMI rationale for OAL of 1.680?  Any ideas?  Could it have something to do w/ the lands?  Some sort of pressure deal?

Must also consider the longest round that would fit and feed from the magazine. I guess it depends from which end they designed for, the action length or the cartridge length. If they went from action length, one has to consider the oal of the round that will fit the magazine. They could have easily made the chamber longer than 33mm, but the action would have to fit the oal.
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Originally posted by Matt_X Matt_X wrote:

  Some place I recently read an explanation of why the military velocities WW2 era were much further out. 


Answer:
The early digital ballistic chronographs were built with vacuum tube logic for counting a crystal time base. The crystals were ultimately traceable to the old Bureau of Standards. I don't know the details of the proximity sensing coil system that was developed between the wars for use in place of breakwires as part of a portable system. I only know that, like the electromechanical devices from the 19th century, its response was slow. Without digital logic, the analog instruments need to make a big enough trace or meter movement to resolve small bits of time. That's why the first screen (wire or coil) was at 6 feet and the second was way out at 150 feet, for an average of 78 feet. That's where the military 78 foot rifle velocity measuring distance came from.
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Nick

We see velocity discussed in documents related to the cartridge development and changes.  This is probably velocity at 78 feet from muzzle.
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SAAMI rationale for OAL of 1.680?  Any ideas?  Could it have something to do w/ the lands?  Some sort of pressure deal?
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I do shoot 85-grain Mauser bullets seated to around 1.625. Hornady has a published load for it. 
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Originally posted by Sawbones Sawbones wrote:

Evansville Cartridge Company 1944 and Lake City 1952 all measured 1.665 +/- 0.002" all chambering beautifully w/o 1 jam.  Likewise the off-the-shelf Sellier & Bellot ammo OALs measuring identically to that of the milsurp.


Observation: 
SAAMI recommended OAL for the 30 carbine cartridge is 1.680".
Milsurp  obviously much shorter at 1.665" +/- 0.002".


Remington Arms Co.  Product Drawing C-30124   Feb 7, 1942
1.680" maximum, 1.660 ? " minimum 
 In pencil next to that looks like 1.679" ? max and 1.637"? min.  Possibly these pencil notes are for production engineering??
Drawing is in Riesch 8th edition, p188.  Unfortunately digitized printing makes it near impossible to read under10x magnification.

Kuhnhausen in figure 30 (p.44) provides the overall length as 1.680 max, but 1.625 min. for commercial.
In note 1 he states the 1.625 minumum accounts for various bullet lengths, but it would be a 1.678" minumum "based on a seated 200955 standard military bullet." 
Phrased that way, I was not sure this 1.678" is actually on a the 1942 and 1943 drawings.

Ruth's War Waby! vol II  has a copy of Ordnance drawing B200954 for Ball Cartridge, revision 5 (10-3-1944).
Overall length is 1.68 with a tolerance of -.02"
By my math that's a minimum on inspection of 1.66"
  Smile
 
 


Edited by Matt_X - May 21 2022 at 1:39pm
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Originally posted by Smokpole Smokpole wrote:

With some of the current powders, it is possible to deliver higher speeds with the same amount of pressure delivered over a longer barrel burn time with slightly slower burning powders like AA9 for example. Case capacity limits the amount of powder, but burn rates can alter the pressure curves quite a bit. I've recently loaded a batch of 115 gr bullets with safe charges of AA9 but haven't had a chance to chronograph the loads yet. I do expect higher than normal velocity, but no increase in pressure signs.

I agree, Lil'Gun fills to case, burns slow enough for good velocities, works the action but does not over work it. To me it seems to burn cool, measures easily and works.

Word of warning,  Lil'Gun should be kept to 45,000 PSI or less, use in higher pressure cartridges has lead to excessive flame temperatures,  enough to damage forcing cones.
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I have never used any AA9, but Hodgdon says H108 is the same as AA9. I load H108 based on AA9 load data and it is a super good powder to handle. Nothing else I have meters and handles as well. I load 13-grains under a 110-grain bullet and have been completely satisfied. I have tested AA7 and it does work, but is a bit faster, yet about the slowest powder you can use in 9mm. I don’t use AA7 routinely, but noticed no ill effects from the few loads I tested. I might use AA7 in carbine loads when I can’t find anything else and I loaded it a bit lighter than H108/AA9. Cycles fine, brass and primers from fired cases looked just fine…no overpressure signs.
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With some of the current powders, it is possible to deliver higher speeds with the same amount of pressure delivered over a longer barrel burn time with slightly slower burning powders like AA9 for example. Case capacity limits the amount of powder, but burn rates can alter the pressure curves quite a bit. I've recently loaded a batch of 115 gr bullets with safe charges of AA9 but haven't had a chance to chronograph the loads yet. I do expect higher than normal velocity, but no increase in pressure signs.
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Originally posted by Smokpole Smokpole wrote:

+P is a higher pressure ammo used in more strongly built firearms. It delivers higher pressures and higher velocities than regular ammo and isn't considered to be safe in many older firearms.

Of course that’s true. + designates an overpressure round. I only mentioned S&B because it is strong ammo, but not labeled as +p. I suspect some stuff labeled +p is not as strong as SB9A.
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+P is a higher pressure ammo used in more strongly built firearms. It delivers higher pressures and higher velocities than regular ammo and isn't considered to be safe in many older firearms.
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FWIW, obviously a different chronograph and location, the S&B velocities measued by -Steve-  in 2009 had a spread of 44 fps over 10 rounds.  Posted here: https://forums.thecmp.org/showthread.php?t=2967  item 8) 

Hey Matt:  I went on the above thread.  A very comprehensive treatise on the 30 Carbine!  Covers everything one would need/want to know.  I recommend it to all Forum folks.
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Floyd, what is “+P”
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I for sure have one carbine that I am only able to shoot mil surp ammo out of, and i bet it’s because it doesn’t like the longer profiles of most commercial ammo or the fatter projectiles in the Armscor

Hey Rebel, I agree.  Ya might seat that stuff down to ~1.665 and see what.  Might remedy your dilemna
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Thanks.  I figured it was prety to close to muzzle, but its always good to check.  Some place I recently read an explanation of why the military velocities WW2 era were much further out.  It had to do with the method of measuring velocity - which if I recall correctly involved high speed photography but in any case required the breaking of two planes at a given distance apart.

Anyways its interesting to have some performance data of WW2 ammo to compare with using the same type of testing.

FWIW, obviously a different chronograph and location, the S&B velocities measued by -Steve-  in 2009 had a spread of 44 fps over 10 rounds.  Posted here: https://forums.thecmp.org/showthread.php?t=2967  item 8)
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Floydthecat: 
I am sorry my statement inferred Sollier & Ballott ammo is crappy, or inferior.  I simply stated the wide range of velocities of of the Sellier & Bellott (65f/) is crappy when compared to that of the milsurp Evansville 1944 (33f/s) ammo and Lake City (42f/s).  It was an opinion derived from decades of competition reloading and shooting.

Velocity is a function of pressures..
The wide variance of velocities adversely affects downrange accuracy.
Hotter loads does not necessarily bestow better accuracy.
Frankly, I am satisfied w/ S & B ammo but if I were going to a 30 carbine competition shoot by all means gimme a coupla bandoliers of Evansville 1944!
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