Bulged M1 Carbine Brass

[hdwhit]

I've been reloading M1 Carbine since I was a teenager. In the decades since, I've handled a lot of brass. In the last year I have received, from two sellers one in Texas, one in Georgia, brass that has a distinct bulge starting 0.230 inches above the case head. The particulars:

• The bluge is not present on every case in either lot.
• The bulge is not confined to any particular headstamp.
• The bulge ranges about 0.020 to 0.023 inches displacement from the line of the case wall.
• The bulge covers about 120 to 180 degrees of the circumfrence of the case.
• The bulge is apparent on visual inspection and can also be felt with the fingertip.
• The bulge is continuous along the case wall and a fingernail will not "hang" up on it.
• Visual inspection of the interior of the case with an otoscope reveals nothing different from brass that does not have the bulge.
• Resizing a bulged case seems to remove the bulge since the resizing die reaches below the bottom of the bulge.
• On an M1 Carbine, the recess in the bolt only covers up the first 0.135 inch of the case, so the bulge is not at the point where the bolt meets the barrel. I am not familiar with other guns that are chambered for the cartridge.

If this were 9mm or 40 caliber brass, I would dismiss it as having been fired in a gun with an unsupported chamber (commonly called "Glocked" brass), but as far as I know, the only guns chambered for the M1 Carbine all have fully supported chambers.

Pistol brass fired from unsupported chambers usually has a distinctive "smile" when resized. When this brass is resized it looks normal and does not have the "smile".



I have included a picture. My first attempts to capture the bulge showed nothing so I used a weak acid to take the shine off the brass for better contrast in the photograph, but the bulge itself remains largely indistinct.

• Has anyone seen this on M1 Carbine before?
• Does anyone know the cause?

These cases were intended to be reformed into 5.7mm Johnson brass. Because that round pretty much pushes the action's 40,000 psi limit, I'm leary of reloading it without having some idea how it came about.

Anything you can tell me will be appreciated.

 

[Catpop]

I'm thinking it was fired in a larger than normal chamber, probably within specs, just on max side. And you're right a normal reloading die will not remove it-because of the shell holder.
However, I had some 357 mag cases with the same problem. I cut the top off an old resizing die and pushed the cases all the way to the rim in a vice. Tapped them out with a flat punch and all was back to normal.
Also I had a custom 270 winchester, with a minimum chamber that would not chamber about 3/4 of my range find brass, but it did fine with new and once fired from my rifle.
Good luck.

 

[WelshShooter]

Don't forget that the Ruger Blackhawk can be found in .30 carbine, so perhaps it was fired in one of those with an oversized chamber?

 

[hdwhit]

WelshShooter wrote:
Don't forget that the Ruger Blackhawk can be found in .30 carbine...

I did not forget about the Blackhawk. I've wanted one in .30 Carbine since I was a teenager, but always seemed to find something else to do with the money.

My understanding is that the chambers in the Blackhawk cylinders were actually fairly tight and this presented a problem for some reloaders because none of the manufacturers offered a "small base" set of .30 Carbine dies (since the 30 Carbine dies were essentially small base already as the guns using the cartridge were the M1/M2 Carbine and the Domincan Republic's San Cristobal sub-machine gun and they needed brass sized to SAAMI minimums for relable performance in their semi-automatic/fully automatic actions).

 

[hdwhit]

Catpop wrote:
And you're right a normal reloading die will not remove it-because of the shell holder.

Please re-read the original post. A normal resizing die reaches to about 0.215 above the case head. As these bulges all begin about 0.230 above the case head, they are fully covered by a normal resizing die.

 

[Dog Soldier]

Maybe they were fired in an M-2 Carbine. The M-2 fires from an open bolt in full auto. The carbine fires from a closed bolt in semi auto. Full auto firearms often bulge case heads.

 

[hdwhit]

Dog Soldier wrote:
Maybe they were fired in an M-2 Carbine. The M-2 fires from an open bolt in full auto.

Are you sure?

See http://www.m1carbinesinc.com/safety.html The M1/M2 carbines both used the same receiver design and it was designed to keep the firing pin from moving forward far enough to reach the primer until the bolt was fully forward and locked.

What is confounding me was that the bulge was not starting where the case wall met the web, where you would expect the bulge to begin to deform in an unsupported case, where we see it occur on 9mm and 40cal rounds fired in unsupported chambers, but about 15/1000 above it.

 

[Blue68f100]

Scrapes like that can happen when the brass is cocked. It could be the base is not square with the body. Bolt not square to the chamber. The fired round is now not true, causing the scrape on one side.

I had one of the early Ruger BH in 30 carbine back in the 70's. It was a fun gun to shoot. I did not remember mine being very picky on ammo.

 

[Gillie Dog]

I just finished inspecting 1K of once fired LC 52, 53 and 54 30 Carbine brass and had one, yes only one, just like that bulge you show/describe which I assumed was from out of battery fire. It is funny I had only one and most all of this brass is in pristine condition. The one with the bulge you could see the shiny ring, very easily, going less than half way around. If it was a over size chamber I would expect to have found more bulged cases than one.

GD

 

[hdwhit]

Dog Soldier wrote:
The M-2 fires from an open bolt in full auto.

Please see this video (link below) produced to describe the differences between the M1 carbine and the M2. In particular, at about time index 6:20, the full automatic cycle is demonstrated and it can clearly be seen the hammer does not fall until the bolt is fully forward and locked.



If that link doesn't work, the video can be found at post #4 here:

http://www.machinegunboards.com/forums/index.php?showtopic=18872

 

[hdwhit]

Gillie Dog wrote:
The one with the bulge you could see the shiny ring, very easily, going less than half way around. If it was a over size chamber I would expect to have found more bulged cases than one.

In this batch of 200 cases, I had 54 that were bulged as described.

I'm thinking that even a careless person wouldn't have continued shooting with that many out of battery discharges. It seems too easy to dismiss it by saying that it was a loose chamber because the M1/M2 carbine does a pretty good job of fully supporting the case and the bulge would suggest a fairly significant failure of the chamber that the shooter just keep firing through.

 

[Swampman]

Maybe they were fired in an M-2 Carbine. The M-2 fires from an open bolt in full auto. The carbine fires from a closed bolt in semi auto. Full auto firearms often bulge case heads.

The only way to lock the bolt back on a .30 Carbine is manually with the pin, or by using a magazine with a square back follower. There is no possible way the sear/trigger could hold it back or release it for open bolt firing.

In any case, an actual out of battery discharge in an M1 Carbine is likely to be a lot more spectacular than the minor bulging seen in that brass.

@ 40 years ago I had a Plainfield .30 Carbine that put the same sort of bulge on every case it fired. It was actually pretty accurate (for an M1 Carbine) and I ended up trading it off to a friend for a beat up Savage 99. I've owned several M1's since then (including another Plainfield that I've still got) but I haven't seen another one that bulged brass like that.

I used to reload the bulged brass with a Lee "Whack-a-mole" set and never had any problems that I can recall.

I'd still size and use cases that looked like that for light cast bullet loads, but as you said, the MMJ is pushing the edge of what the action and brass were designed for.

I doubt weakness that far from up from the web would cause dangerous or catastrophic failure, but why chance it? .30 Carbine brass is expensive, but it's way cheaper than a hospital visit or wrecked rifle.

 

[Kevin Rohrer]

Maybe they were fired in an M-2 Carbine. The M-2 fires from an open bolt in full auto. The carbine fires from a closed bolt in semi auto. Full auto firearms often bulge case heads.

Huh? The M2 Carbine I fired did so from a closed bolt.

 

[Carl N. Brown]

I have an IBM made M1 Carbine dated 1943 and apparently original IBM barrel 70+ years old. Checking box of brass I fired on the Sep 2016 military match, there is a bit of expansion of case body just before the head on just about all casings. Perhaps a combo of closer to minimum dimension brass and closer to maximum dimension chamber. Brass left by shooters using new commercial carbines tend show less of a bulge or ring.

 

[hdwhit]

swampman wrote:
@ 40 years ago I had a Plainfield .30 Carbine that put the same sort of bulge on every case it fired.

Thank you. That is precisely the information I was seeking.

My 5.7mm Johnson is stamped as having been made in New Jersey (which means it's actually a Plainfield, just one made in New Jersey after the acquisition, but before the move) rather than having been made in Jacksonville, Arkansas.

It's a strange fact that as the re-located Iver Johnson was approaching it's "appointment with destiny", I was working just down the road in Lincoln County. As a Mechanical Engineer, Forensic Engineer, MBA and a Carbine afficianado, I believed I saw a way forward for their product and pitched my services to them. By the time they said they were not interested, the fate of the company had already been sealed by the bankruptcy court and I had to move on. Still, I often wonder what could have been had they responded earlier (especially becuase the "carbine afficianado" part of my resume brought with it a nearly unlimted source of capital). Kahr and Inland might never have been known had I been able to acquire the rights to the Plainfield receiver and process for hardening it to GI specs.

A nearly-forgotten chapter of firearms lore.

 

[ReloaderFred]

Huh? The M2 Carbine I fired did so from a closed bolt.

The M2 Carbine has never fired from the open bolt, and couldn't possibly, due to the design of the system, as hdwhit so aptly pointed out. I've fired several M2 Carbines, and they all shot from the closed bolt, and other than being too light for full auto use, it was a quick way to go through a lot of ammo.

Hope this helps.

Fred

 

[bihj]

I own a carbine (have for many years) and the brass from it has always produced this bulge. Before I had this carbine, my father owned it and I reloaded for him. The brass from this carbine made the bulge during this time also. There has been NO problems with reloading this brass or the carbine during my ownership or when my father owned it. The brass seems to last from between 15 - 20 loading's before I start to experience splits.

 

[forestswin]

Take a look at this SAMMI drawing

Is what you are seeing the end of the taper and the beginning of the constant diameter?
I don't see this in my cases, though

 

[Sunray]

"...M-2 fires from an open bolt..." Nope. Closed, same as an M1.
Have had a Plainfield .30 Carbine for more than 40 years that doesn't.
Gotta be some flaw in that particular firearm. Or the way the case was resized.