Ideas on what caused this?

[james nicholson]

Did not know where to post this, so I started here. I pick up brass from the sheriff dept range and I found some strange brass. Head stamp is Speer, 40 S&W, but there are markings on the outside that looks like it was somehow forced into the rifling at least 3/8". After tumbling for 3 hours, the markings are still there. If you feel the outside you can feel the grooving on the case. I ran some through the sizing die and it smoothed it somewhat and took away the grooving almost all the way. I have pictures on my phone, but not sure how to get them to my post. Did anyone ever hear of a pistol with a rifled chamber?

[dondiego]

Some H&K rifles had fluted chambers but have never heard of a pistol to have any.

[475AR]

Did not know where to post this, so I started here. I pick up brass from the sheriff dept range and I found some strange brass. Head stamp is Speer, 40 S&W, but there are markings on the outside that looks like it was somehow forced into the rifling at least 3/8". After tumbling for 3 hours, the markings are still there. If you feel the outside you can feel the grooving on the case. I ran some through the sizing die and it smoothed it somewhat and took away the grooving almost all the way. I have pictures on my phone, but not sure how to get them to my post. Did anyone ever hear of a pistol with a rifled chamber?

More than likely it was shot out of an mp5, I
think 9, 40 and 10mm had fluted chambers but not 100% on that

[james nicholson]

This very well could have come from a submachine gun, the SWAT guys use H&K 40 cal.

[Reddirt62]

This is one fired from an mp5.

Sent from my SM-N920V using Tapatalk

[lightman]

I agree that those were probably fired in an H&K. I've reloaded 223's and 308's like those before without any problems except that they make for an ugly looking cartridge.

[dondiego]

I think that I read somewhere that it helped spent cartridge removal from a dirty chamber.

[Walter Laich]

learned two things:

what cases look like when fired from MP5

and you can reload them

good to know

[17nut]

I think that I read somewhere that it helped spent cartridge removal from a dirty chamber.

No!

It just facilitates easy extraction from a chamber that is under pressure. All the H&K's uses delayed roller blowback and need pressure om both sides of the brass to ease extraction.

https://www.youtube.com/watch?v=Xusr9M9cHr4

[country gent]

I believe it also slows the cycle rate down some.

[OS OK]

I guess that Gluck is not the only one out there messing up good brass!