9mm brass with a shelf inside

PaulS · Posted: Wed Sep 27, 2017 4:48 pm Post subject: 9mm brass with a shelf inside

While going through my cleaned range brass I found some 9mm brass that has a shelf about half way down the inside of the case. I found 8 pieces and they all shared the same head stamp; "FM 9mm"
I was curious so I weighed them and they are a lot heavier than any other brass I have. They have about 3 grains less capacity than a standard 9mm brass. I assume they can be reloaded with a lesser charge but not by me. I put them in the recycle bin. Has anyone else run into these things?

Pumpkinslinger · Posted: Wed Sep 27, 2017 6:09 pm Post subject: Re: 9mm brass with a shelf inside

Paul, take a look here, www.calguns.net/calgun...p?t=947361

RePete · Posted: Wed Sep 27, 2017 6:26 pm Post subject: Re: 9mm brass with a shelf inside

I've used it and had no problems.

slimjim · Posted: Fri Sep 29, 2017 4:48 am Post subject: Re: 9mm brass with a shelf inside

Thanks, PaulS. I will keep an eye out for this and keep them separate.

Gil Martin · Posted: Sat Sep 30, 2017 5:46 am Post subject: Re: 9mm brass with a shelf inside

I have not yet encountered 9mm brass with a shelf inside. Any such brass that comes my way will end up in the recycle bin. All the best...
Gil

PaulS

I normally work up loads specific to my guns. I am in the process of doing that for the 9mm. I don't want two loads with different cases so I will just junk them as I find them.
I have plenty of brass so I don't need them.

RePete

Paul:

I don't sort my brass, just load it and shoot it.

Vince · Posted: Sun Oct 01, 2017 6:43 pm Post subject: Re: 9mm brass with a shelf inside

Has anyone thought to ask the manufacturer about the cause or reason for the "shelf"?

Assuming it hasn't thinned out the brass in the sides of the case, and it lets the bullet seat fully, I'm thinking it shouldn't be a problem. Only drama I can see, once again assuming the wall of the case is not affected, would be a possible alteration of the burn characteristics because of a false smaller or tighter "case mouth" inside the case causing a possible pressure spike.

RePete · Posted: Mon Oct 02, 2017 3:17 pm Post subject: Re: 9mm brass with a shelf inside

It's more than likely there to prevent bullet setback during the violent loading.

PaulS · Posted: Tue Oct 03, 2017 4:48 pm Post subject: Re: 9mm brass with a shelf inside

One of the representatives said the step was caused by the way they make their brass but no one else has the problem.
If a reloader loads to even 90% of maximum loads with this case the available powder space, or lack of space, is likely to generate much higher pressures. A few individuals have stated that cases have separated at the shelf leaving the upper half of the case in the chamber. I can see this happening with near maximum loads in the reduced capacity cases. Reducing the capacity of a case that is widely used without some kind of warning seems a bit negligent but then I am a reloader who doesn't often buy factory ammo. It just gives me one more thing to watch out for.
If anyone wants this brass I will separate it from the recycle bin and keep it until I have enough to transfer to you.