Odd marks on 9mm cases

[BB in Texas]

Has anyone seen cases with marks like the pictures below? I picked these up at the range—they’re not from any of my firearms. The case heads and primers don’t seem to be abnormal so I am left wondering why the odd shooting pattern.

 

[H&R Glock]

fired in fluted chamber, like on a sub gun?

 

[9mmepiphany]

Those are the marks left on a case by fluted chambers commonly found in a H&K P7 or a MP5

 

[BB in Texas]

fired in fluted chamber, like on a sub gun?

Thanks.

 

[BB in Texas]

Those are the marks left on a case by fluted chambers commonly found in a H&K P7 or a MP5

Thanks.

 

[milsurpguy]

Yeah I found some of those too, took a good wet tumble in SS pins to remove. Fluted chambers are at the very least very annoying to people who pick up brass and reload it. They don't appear to be necessary since every other manufacturer has figured out how to make their 9mm rifle or carbine work with out fluting.

I vaguely remembered something about HK and fluting, but not on 9mm so I took them to my HK guy. The HK guy said they came from some HK pistol I don't remember the name of or mp5.

 

[9mmepiphany]

They don't appear to be necessary since every other manufacturer has figured out how to make their 9mm rifle or carbine work with out fluting.

You might change you mind if you'd read about a 65k round torture test run on a P7 a while back. Somewhere just before 40k rounds the extractor broken and was lost...it still continued to work for over 25k rounds.

On rifle and carbines, they are part of the reliability package of the Roller-Delayed blowback system that allows the rifle to run with everything from pip squeak loads to overloads without adjustment to a gas system.

In the MP5 it produces the most reliable and accurate subgun every produced

 

[jmorris]

I am with the P7/MP5 group. My Scheuman AET barrels are also fluted but the spacing is different.

 

[Mk-211]

I used to have an HK-91 and 94, both had fluted chambers and would leave those marks on the brass.

They say that you can still reload the brass but I never did. Didn't want to take the chance as the flutes really dug into the brass.

 

[GeoDudeFlorida]

Those are the marks left on a case by fluted chambers commonly found in a H&K P7 or a MP5

Yup. My P7M8 did that to brass. Fluted chamber H&K.

 

[Riomouse911]

I’ve put cases and cases and cases of 9mm through Mp5 and Mp5k subguns. The cases all come out fluted like those.

I can’t recall one single FTE in the three decades I’ve shot them... many times during 750-1000 round full auto and burst session training days.

I don’t know if they needed the flutes to be so reliable or not...but man do those guns run!

Stay safe.

 

[BB in Texas]

My thanks to all of your for responding and sharing your knowledge. This is a great forum for learning and solving problems. Have only been a shooting enthusiast for 2 years and reloading only about six months. Will never have the firearm sophistication of most of you, but I really enjoy the sport and learning every day.

 

[EricBu]

LIke everybody else said, fluted chamber from roller lock..HK or HK clone. They make reloading kind of a pain. I've owned a MP5 clone, a PTR-32 (7.62x39), and a PTR-91. They were all destroyers of brass. Especially the 7.62x39...I'd only get 2 or 3 loads out of brass in it before that brass was done.

 

[Zendude]

Interesting T&M headstamp. Which ammo companies source their brass from Truelove & Maclean these days?