45 cal bulged case

[OWGEM]

Anyone ever see anything like this? Found at the range, several with bulged primers as well. The case has a raised ridge in the middle. Any ideas?

 

[EyeCarry]

.

 

[Leadeye]

New to me, when I've seen 45 ACP bulged cases it always around the base.

 

[red_zr24x4]

What Leadeye said. Never seen anything like it that I can remember

 

[Tombs]

I wonder if someone had a go at "polishing" their chamber and got a little wild with the dremel...

That'd be my first guess.

 

[Bigtanker]

Delayed blowback gun? Detonics used a similar action type on one of their small 9mm.

There is a small ring cut into the chamber that allows the brass to expand just a little to let chamber pressure drop before the case is allowed to move backwards ina blowback action.

From an article on the Detonics.

The Pocket 9 uses an interesting obturation-delayed blowback mechanism, whereby brass cases are allowed to expand outward into a ring cut in the barrel’s chamber. This delays the separation of the case and the barrel long enough to maintain a reasonable slide and return spring weight.

They made a pocket 45 too.

 

[Bigtanker]

Here is some brass fired from a HK P7PT8 version. It's in 9mm. It uses the chamber ring delayed blowback system.

I'm wondering if there is a .45acp upper using this system.

 

[Wolfhound]

Like most of you, I have never seen anything like that. And I just learned something thanks to Bigtanker.

 

[Leadeye]

Learn something new everyday.

 

[OWGEM]

Delayed blowback gun? Detonics used a similar action type on one of their small 9mm.

There is a small ring cut into the chamber that allows the brass to expand just a little to let chamber pressure drop before the case is allowed to move backwards ina blowback action.

From an article on the Detonics.



They made a pocket 45 too.

That would seem to explain it. Thanks!!!

 

[Bigtanker]

I just learned about it by listening to Handguns podcast. Just passing on the info.

 

[russc2542]

Here is some brass fired from a HK P7PT8 version. It's in 9mm. It uses the chamber ring delayed blowback system.

I'm wondering if there is a .45acp upper using this system.

A what? google says the P7 PT8 is a precursor to simunition that can't fire conventional ammo. The regular P7 (any variant) is a piston delayed blowback. The marks on the brass are lengthwise from the fluted chamber that are to help the brass out of the chamber. Here's a much better pic:

The P7M8 and M13 are 9mm, P7M10 is .40. There's a P7M7 in .45 but there were only 3 prototypes (or so I heard) and uses a hydraulic blowback buffer (shock absorber) rather than the gas delay of the others. The Walther CCP has a similar gas-delay system but otherwise is like comparing a Trabant to BMW in it's prime.

 

[Old Dog]

Is this possibly from a full auto Thompson (Tommy gun) firing from an open bolt? I don't know, just my best guess.

 

[EyeCarry]

I found a casing just like this while recovering brass at a steel challenge. I had no idea what it came from.

A what? google says the P7 PT8 is a precursor to simunition that can't fire conventional ammo. The regular P7 (any variant) is a piston delayed blowback. The marks on the brass are lengthwise from the fluted chamber that are to help the brass out of the chamber. Here's a much better pic:

The P7M8 and M13 are 9mm, P7M10 is .40. There's a P7M7 in .45 but there were only 3 prototypes (or so I heard) and uses a hydraulic blowback buffer (shock absorber) rather than the gas delay of the others. The Walther CCP has a similar gas-delay system but otherwise is like comparing a Trabant to BMW in it's prime.

 

[Bigtanker]

Found one!!

https://www.cmmginc.com/product/pistol-mkg-45-psb-45-acp/

The CMMG MkG GUARD is a new AR15 chambered in the iconic .45 ACP. The GUARD is fed from factory Glock 21 magazines and uses CMMG’s patent pending Radial Delayed Blowback operating system that tames the .45 ACP cartridge while simultaneously reducing the weight and felt recoil of the rifle.

 

[russc2542]

Found one!!

https://www.cmmginc.com/product/pistol-mkg-45-psb-45-acp/

I read about that when someone had a 9mm version fs a bit ago. I think you were closer with the obturation delayed blowback before. From what I gleaned from the material they had, the CMMG radial delayed blowback puts an angle on the lugs so the rearward force is diverted into rotating the bolt, once it rotates enough to unlock the chamber pressure has dropped significantly thus not needing nearly as heavy of a bolt to handle the blowback portion. Side note: from dealing with fastener torques it seems like that'd be really sensitive to cleanliness and lube. (like lube on the threads affecting fastener tension at a given torque)

I found a casing just like this while recovering brass at a steel challenge. I had no idea what it came from.

Was it the HHRP range near nashville? if so that'd be mine.

 

[Brad69]

I say M3 “grease gun”
In the long ago days I “qualified” with the M3 which means I fired it you cannot really hit much with one.
If my mind recalls correctly from when I was a 17 year old the brass had bulging like pictured.
We spent more time picking up brass than shooting.

 

[Thor]

The M3 will shoot it a lot faster than you can pick it up...and the M3 shoots it pretty slow. I think they cost like $17 to make...

 

[Drail]

I believe that is a two piece case. I have seen them but have no idea what the advantage or purpose is but they are on the market. Maybe easier to manufacture? I don't know.

 

[russc2542]

I believe that is a two piece case. I have seen them but have no idea what the advantage or purpose is but they are on the market. Maybe easier to manufacture? I don't know.

These are 2 piece cases https://www.shellshocktechnologies.com/. the seam's much lower, materials different, and they don't make .45.