May 1944 Ammo Test?

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   What sort of ammunition test might have been conducted in May of 1944?
This carbine serial number popped up as a not very close 'nearest' to a request if there was a match in the Springfield Research Service books (CMP forum).
 Underwood 1406057     051144FA AMMO TEST. 

The 1.40xx,xxx Underwoods on the spreadsheets had March and April 1943 barrels.
May 14, 1944 is long after, so I presume this ammo test was not of production carbines.

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Matt_X Members Profile Send Private Message Find Members Posts Add to Buddy List Hard Corps Joined: Nov 10 2020 Location: Phila, Penn Status: Offline Points: 771	Post Options Post Reply Quote Matt_X Report Post Thanks(0) Quote Reply Topic: May 1944 Ammo Test? Posted: Sep 21 2021 at 8:39pm
	What sort of ammunition test might have been conducted in May of 1944? This carbine serial number popped up as a not very close 'nearest' to a request if there was a match in the Springfield Research Service books (CMP forum). Underwood 1406057 051144FA AMMO TEST. The 1.40xx,xxx Underwoods on the spreadsheets had March and April 1943 barrels. May 14, 1944 is long after, so I presume this ammo test was not of production carbines.

New2brass Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Dan Pinto, Photo Editor Joined: Nov 29 2015 Location: CT Status: Online Points: 4660	Post Options Post Reply Quote New2brass Report Post Thanks(0) Quote Reply Posted: Sep 22 2021 at 10:34am
	Matt, If you have WB2 there is a chapter on ammo. Quick look it may have been clad-steel ammo. With the exception of pre production test, all other carbines tested were production carbines! Grabbing an earlier carbine may have been due to change in the case (mid 43?) as the chambers were changed. Basically if someone was to take the early dated (COLLECTABLE) ammo and try shooting in a later carbine they may have an issue. The reason early lots still exist is that after the chamber change all previous ammo was pulled and not sent to the theaters of operation.
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Matt_X Members Profile Send Private Message Find Members Posts Add to Buddy List Hard Corps Joined: Nov 10 2020 Location: Phila, Penn Status: Offline Points: 771	Post Options Post Reply Quote Matt_X Report Post Thanks(0) Quote Reply Posted: Oct 20 2021 at 9:44am
	Steel ammo tests sounds reasonable. I only have War Baby! Looking it over again I'm a little confused about the ammunition change timeline. I understand the earliest 2 lots were called .30 Light rifle and have unmarked headstamps. (page 8) On page 166 is a section titled Problems with Overloaded Ammunition It describes a test on September 18, 1943 where "purposely overloaded ammunition" had been supplied. That this ammunition increased the muzzle velocity to 1,900 fps. This confuses me. I can't find the page now abpout the rechambering, but I thought the cartridge and chamber size was finalized during the trials. This included a change of powder. My understanding is 1,900 fps is the low side of a military spec .30 Carbine cartridge. If makes no sense to me the overloaded ammo only produced 1,900 fps. I know load pressures are not linear with muzzle velocity, just saying I can't make sense of what changed in 1943 and how it relates to 'overloaded' ammo.

Matt_X Members Profile Send Private Message Find Members Posts Add to Buddy List Hard Corps Joined: Nov 10 2020 Location: Phila, Penn Status: Offline Points: 771	Post Options Post Reply Quote Matt_X Report Post Thanks(0) Quote Reply Posted: Oct 20 2021 at 1:50pm
	In Ruth's earlier book, he writes that the velocity of the muzzle velocity of the cartridge was brought "up to the desired 2000 feet per second" in early 1942. Maximum chamber pressure was kept to 33,000 psi. (M1 Carbine: Design, Development & Production page 39.) Also, although not an ammo test, on page 72 there is a barrel endurance comparison April 5 to June 21, 1944 at Aberdeen. Two Underwoods are listed for the test; 1350219, and 1446485.

New2brass Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Dan Pinto, Photo Editor Joined: Nov 29 2015 Location: CT Status: Online Points: 4660	Post Options Post Reply Quote New2brass Report Post Thanks(0) Quote Reply Posted: Oct 21 2021 at 2:43pm
	WB2 pgs 677-704 is a chapter on ammo pg 678 Further Improvements to the .30 Carbine Cartridge The original round as standardized in 1941 had too radical of a case taper and was changed on June 11, 1943 (rev 4 to Dwg B200954) taper was 0.031 in. inclination, which extended to within 0.39 of the mouth. then no taper to mouth. after June11. 1943 had a taper of 0.027 to 0.32 of mouth. the taper was enough that earlier ammo would not chamber in weapons with the new chamber. this required a special suspension order to prevent issue of certain early ammunition lots on hand that might be used in later weapons. it goes on to discuss problems satisfactory propellant and work continued after the round was adopted. April 6, 1943 drawing was revised, raising velocity from 1800 to 1900 fps @ 40000psi. this was discussed a bit with the rear sight on the Inland 270 article
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Matt_X Members Profile Send Private Message Find Members Posts Add to Buddy List Hard Corps Joined: Nov 10 2020 Location: Phila, Penn Status: Offline Points: 771	Post Options Post Reply Quote Matt_X Report Post Thanks(0) Quote Reply Posted: Oct 22 2021 at 9:10am
	Appreciate the explanation. I'm still quite confused about the specific changes. At least to me, the descriptions don't make sense. For example, the earlier cartridge with a steeper taper and longer straight sided nose should have more clearance to fit in the new chamber. (see rough sketch) Another is if the pressures of the new cartridge were increased so much (100% ) as to cause a stoppage at Saginaw and other plants due to broken bolts, is that a reference then to proof cartridges? Because 33,000 to 40,000 psi is a lot, but not 100%. That leaves the info in Ruth's earlier book, which we could assume is wrong, or just as likely, that the velocity cited there is measured that a different point than the velocities cited in WB2. For example one document might be discussing a design spec and some later correspondence might be discussing results based on a measurement method that is x number of yards away from the muzzle. Sketch of early production cartridge in early production chamber (top) and then same cartridge in a chamber revised for longer taper and shorter straight wall.

New2brass Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Dan Pinto, Photo Editor Joined: Nov 29 2015 Location: CT Status: Online Points: 4660	Post Options Post Reply Quote New2brass Report Post Thanks(0) Quote Reply Posted: Oct 22 2021 at 10:11am
	Matt, Ruth states "too radical of a case taper" From a machinists or mechanical point of view, By moving the straight forward it smooths the inclination or less taper. with a taper, when the two parts match, the surface area gives "grab" but when you move it out ever so slightly it completely lets go. when the two tapers do not match there is less surface area, which would seem less grab. however, you would get a small area of binding and the rest of the area teeters which can cause binding. Then looking at it as a chamber, the case would possibly expand unevenly and possibly cause the malfunctions that is talked about? Dunno? then there are other factors such as the case is smaller than the chamber to allow for expansion, ease of insertion, extraction. So there are many factors why the early ammo would malfunction in later chambers but late ammo worked in earlier chambers. The source for Ruth's information is frm "history of Modern US Military Small Arms Ammunition Volume II: 1940-1945 by F.W. Hackley, W.H. Woodin and E.I. Scranton. I believe their source would be ordnance documents as they mention the Ordnance Committee minutes.
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Matt_X Members Profile Send Private Message Find Members Posts Add to Buddy List Hard Corps Joined: Nov 10 2020 Location: Phila, Penn Status: Offline Points: 771	Post Options Post Reply Quote Matt_X Report Post Thanks(0) Quote Reply Posted: Oct 22 2021 at 10:37am
	Thanks Dan. Although I'm not a machinist I'm familiar with Morse tapers and boy they do hold tight, don't they.

Matt_X Members Profile Send Private Message Find Members Posts Add to Buddy List Hard Corps Joined: Nov 10 2020 Location: Phila, Penn Status: Offline Points: 771	Post Options Post Reply Quote Matt_X Report Post Thanks(0) Quote Reply Posted: Dec 14 2021 at 10:24am
	Someone posted that the tight fit issue is with the diameter. This would appear to be correct. The original case drawing shows an outside diameter as large as 0.3560 inches. Based the drawing in Kuhnhausen, this was reduced to a maximum of 03.548 inches. Although the June '43 revised chamber dimension at the same reference point should allow the old cartridges to fit, apparently removal sometimes may be a problem. Whether they get locked in unfired is not clear, but certainly after firing they must have found or knew from experience that there would be some that shells would get stuck. The unrevised case drawing is reprinted in War Baby III. Kuhnhausen page 44 has a composite drawing showing post June '43 case dimensions.

New2brass Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Dan Pinto, Photo Editor Joined: Nov 29 2015 Location: CT Status: Online Points: 4660	Post Options Post Reply Quote New2brass Report Post Thanks(0) Quote Reply Posted: Dec 14 2021 at 11:17am
	Would be interested in seeing the two drawings overlaid. It would probably need to be done in a CAD program to get accurate lines and then you could visualize points of contact or excessive space.
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