im shooting a 16" 9mm AR i put a 7.5oz 9mm buffer and a .308 buffer spring. steel cased ammo would have a failure to feed once in a while. brass seems to feed ok. could my buffer setup be causing the failures to feed? or is the steel cased ammo known for this failure? only have 70 rounds thru it so far. cleaned and lubed and will put more thru it and see if it does it again. unless i should stay away from the steel.

I can't really think of why steel cases might cause failures to feed. Maybe there is a reason, but I don't know what it is.

I usually look at the magazines first when I get failures to feed in an AR.

I also don't know enough about 9mm ARs to comment on your buffer and spring set up. I know that some use AR10 springs in them, but I don't know what problems they might solve or introduce into the system. In general, though, the buffer and spring system can be related to feeding problems.

Why fire steel cased ammo? It escapes me, to maybe save 2 bucks a box. Just my opinion. 9 millie brass cased is a bargain currently.

What kind of failure to feed? it doesn't pick up the round? something else? what kind of 9mm setup? 9mm can be finicky so need a whole lot more detail. But having said that nothing that I have seen about steel case is an issue for pure feeding (but of course its usually pretty wimpy stuff so short stroking is a real potential)

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Originally posted by blasto:
Why fire steel cased ammo? It escapes me, to maybe save 2 bucks a box. Just my opinion. 9 millie brass cased is a bargain currently.

Exactly. It is cheaper. If you buy in bulk and shoot a lot, it adds up. As much as $50 per 1000 rounds, in comparing the cheapest steel ammo to the cheapest brass.

I'm using glock mags or the clear ones made by ETS I believe. The case will have a dent in the side of it as if it is catching on the edge of the barrel as it's coming out of the magazine.my first thought was the bolt didn't recoil enough for a full stroke. I'm going to shoot it some more and see if it gets better after shooting more rounds through it.

The only mags that are reliable in my 9mm AR are Metal form.

I don't know why but cheap mags aren't even worth trying IMO.... Good luck !

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The only mags that are reliable in my 9mm AR are Metal form

This isn't related to the issue at hand. Metalform mags run in Colt style AR lowers and canrunin is running a glock style lower.

You should be fine on a 7.5 buffer, but the .308 buffer spring might be a bit excessive. I use a Spikes 8oz and a standard carbine spring and it eats everything - including steel.

9mm's can be very finicky, but a lot of the malfunctions I have read about have been because of too much spring using weak ammo. I would give it a try with a standard carbine spring.

Another issue that seems to be common is a poorly cut feed cone on the barrel. Is this an off-the-shelf or did you build it?

This message has been edited. Last edited by: RB211,

I'm using a complete upper from Moriarti armaments.they put it together came with big and charging handle.i gave it a good cleaning and this weekend I'm going to run it with a standard spring and the 308 spring and see what happens.thanks a lot.