Hey guys, I just got a new M&P sport II and took it to the range yesterday and today. I used the 30rnd Pmag it came with along with a box of 300 rounds of Federal Black Pack 223 Rem. 55 GR ammo. Within the first magazine I had issues of it firing a couple rounds fine, then a click, with no bang. Take out magazine, rack a new round, same thing. A few shots all good then a click. Examined the round that was chambered but not fired and it appears the primer was struck and its shell casing has a scuff mark, slightly crushed almost to where the bullet was borderline bent. It did this off and on yesterday so today I bought a new pmag and a box of federal American eagle 5.56X45mm, 55GR. No issues using the new mag and 20rnds of 5.56, no failures what so ever. Then I used the new mag with the previous 223 ammo and same thing was happening as previous day. Any idea what it might be? I’ve included pics of the failed rounds. The gun was thoroughly cleaned and lubed prior to the range visit.
AR M&P sport II issues
- Thread starter Jmac77
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Well...sounds like you have followed all the steps to determine the problem lies with the Federal Black Pack ammo. Just did a search and found this review and photo on Palmetto State Armory's page for this product:
Not impressed at all by this product.
I did not like this product. I did receive exactly 300 rounds and I got them very fast but 60 of them looked like someone smacked them with a hammer. 60 useless rounds out of 300. Not what I signed up for. Federal needs to do better than this.
December 9, 2018
Matt C
Sounds like they just had a bad run of ammo
Not impressed at all by this product.
I did not like this product. I did receive exactly 300 rounds and I got them very fast but 60 of them looked like someone smacked them with a hammer. 60 useless rounds out of 300. Not what I signed up for. Federal needs to do better than this.
December 9, 2018
Matt C
Sounds like they just had a bad run of ammo
Blue68f100
Member
I've seen this with ammo that does not have enough energy to drive the bolt back far enough. Short stroking. Bad magazines can cause this too. Does it load properly when you release the bolt using the catch?
My first thought was a bad batch of ammo but it was happening so frequently I didn’t think it could possibly have that many duds in there. I’ll contact Federal and see if this is a common thing they’ve been experiencing lately with this brand of ammo.
I used two separately bought brand new pmags to try and eliminate the bad mag variable. Maybe it’s possible the 223 doesn’t have enough energy to fully drive the bolt back and forth being a brand new gun and still tight? I lubed it very well but I could always try exclusively using 5.56 ammo for the next hundred or two hundred rounds to see if it helps loosen and smooth things out then go back and try some 223. It loads properly when using both the catch release and sling shotting the charging handle. If I recall correctly the first shot always fired but it was the second, or fourth, fifth, etc, round that did not.
I've fired both 223 and 556 in my sport 2, never noticed any difference in operation. If its running smoothly with the American Eagle, I doubt there's anything wrong with the action, just sounds like out of spec ammo. When the bolt short strokes, it usually results in a jam...not a failure to fire on a chambered round, though to make sure, just get some other brand of 223 and see how it does. Take a look at the primers, see if the Black Pack primers are seated deeper than the AE primer, that would give you light strikes, as to the dents, make sure they're not like that out of the box. Also, take a look at your fired brass...see if any of those have scuff marks.
Varminterror
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That’s a bad feed. The photo from PSA’s page is a very different failure, and chasing that rabbit will only waste your time. The OP’s rifle is BARELY getting ahold of the round at the edge of the bolt lug, which then causes it to crash on the chamber mouth. Ever so slight, as it is finishing feeding into the chamber, but it’s still crushing the round, which isn’t allowing the round to fully seat, which holds the bolt slightly out of battery. The hammer can drop, but with the BCG slightly out of battery, it’s not getting a full power punch on the primer.
Short stroking is usually the cause for missed pick ups, or ALMOST missed pick ups, as we’re seeing here. It can also be caused by a slow mag follower, or a mag sitting too low in the receiver, but it’s almost always a short stroke. A mag dragging on the bottom of the BCG can cause that short stroke, as can low powered ammo, plugged buffer tube port, misaligned gas block, bad gas rings, leaking gas system... Trying a different mag is the easiest option. Trying different ammo is also simple. “Pressure testing” the gas system is a little more work, but relatively easy to do - remove the BCG, block the chamber with a fired round, blow into the muzzle. You’ll be able to feel whether air is freely running in the gas tube, or if there is some obstruction. Leaks usually reveal themselves with witness marks of carbon blast, around the gas tube or gas block. Checking your gas rings is easy as well - sling the bolt forward in the carrier like swinging ketchup to the mouth of a bottle, then stand the carrier up on end. If it collapses, replace the rings.
Most likely it’s just a bad mag, dragging on your BCG.
Short stroking is usually the cause for missed pick ups, or ALMOST missed pick ups, as we’re seeing here. It can also be caused by a slow mag follower, or a mag sitting too low in the receiver, but it’s almost always a short stroke. A mag dragging on the bottom of the BCG can cause that short stroke, as can low powered ammo, plugged buffer tube port, misaligned gas block, bad gas rings, leaking gas system... Trying a different mag is the easiest option. Trying different ammo is also simple. “Pressure testing” the gas system is a little more work, but relatively easy to do - remove the BCG, block the chamber with a fired round, blow into the muzzle. You’ll be able to feel whether air is freely running in the gas tube, or if there is some obstruction. Leaks usually reveal themselves with witness marks of carbon blast, around the gas tube or gas block. Checking your gas rings is easy as well - sling the bolt forward in the carrier like swinging ketchup to the mouth of a bottle, then stand the carrier up on end. If it collapses, replace the rings.
Most likely it’s just a bad mag, dragging on your BCG.
Kp321
Member
Varminterror mentioned gas rings. I have seen some posts on the S&W forum about early gas failure on M&P's so don't discount the possibility. Gas rings are cheap and easy to install.
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