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Milsurp OAL vs SAAMI OAL |
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Matt_X
Hard Corps Joined: Nov 10 2020 Location: Phila, Penn Status: Offline Points: 771 |
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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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Matt_X
Hard Corps Joined: Nov 10 2020 Location: Phila, Penn Status: Offline Points: 771 |
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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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New2brass
Moderator Group Dan Pinto, Photo Editor Joined: Nov 29 2015 Location: CT Status: Offline Points: 4664 |
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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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Sawbones
On Point Joined: Mar 04 2022 Location: Texas Status: Offline Points: 152 |
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So sorry for the late response. For reason unknown the Forum is not alerting me of replies. Quality Hardware 1,583,8XX 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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"Always do sober what you said you'd do drunk. That will teach you to keep your mouth shut." Ernest Hemingway
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New2brass
Moderator Group Dan Pinto, Photo Editor Joined: Nov 29 2015 Location: CT Status: Offline Points: 4664 |
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@Sawbones, What carbine and serial range are you using?
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floydthecat
Hard Corps Joined: Oct 13 2016 Location: Mississippi Status: Offline Points: 1998 |
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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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Matt_X
Hard Corps Joined: Nov 10 2020 Location: Phila, Penn Status: Offline Points: 771 |
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Answer:
quoted from CMP forum https://forums.thecmp.org/showpost.php?p=258647&postcount=12 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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Sawbones
On Point Joined: Mar 04 2022 Location: Texas Status: Offline Points: 152 |
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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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floydthecat
Hard Corps Joined: Oct 13 2016 Location: Mississippi Status: Offline Points: 1998 |
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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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Matt_X
Hard Corps Joined: Nov 10 2020 Location: Phila, Penn Status: Offline Points: 771 |
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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" Edited by Matt_X - May 21 2022 at 1:39pm |
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David Milisock
On Point Joined: Aug 03 2019 Location: USA Status: Offline Points: 334 |
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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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David Milisock
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floydthecat
Hard Corps Joined: Oct 13 2016 Location: Mississippi Status: Offline Points: 1998 |
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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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Smokpole
Hard Corps Joined: Oct 21 2019 Location: Madison ohio Status: Offline Points: 1058 |
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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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floydthecat
Hard Corps Joined: Oct 13 2016 Location: Mississippi Status: Offline Points: 1998 |
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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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Smokpole
Hard Corps Joined: Oct 21 2019 Location: Madison ohio Status: Offline Points: 1058 |
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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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Sawbones
On Point Joined: Mar 04 2022 Location: Texas Status: Offline Points: 152 |
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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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"Always do sober what you said you'd do drunk. That will teach you to keep your mouth shut." Ernest Hemingway
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Rebel92
Grunt Joined: Jul 20 2021 Location: Hattiesburg, MS Status: Offline Points: 541 |
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Floyd, what is “+P”
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Sawbones
On Point Joined: Mar 04 2022 Location: Texas Status: Offline Points: 152 |
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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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"Always do sober what you said you'd do drunk. That will teach you to keep your mouth shut." Ernest Hemingway
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Matt_X
Hard Corps Joined: Nov 10 2020 Location: Phila, Penn Status: Offline Points: 771 |
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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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Sawbones
On Point Joined: Mar 04 2022 Location: Texas Status: Offline Points: 152 |
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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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"Always do sober what you said you'd do drunk. That will teach you to keep your mouth shut." Ernest Hemingway
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