M&P10 short stroking

[cc426]

Having problems with my new m&p10 short stroking. Shooting 308 (not the NATO rounds) factory loads. Tried 168, 145 couple different brands.

Bolt not traveling far enough to strip a round. Not enough force to chamber a round. Not holding open on last shot. Etc.

Seems to happen about 1/5 rounds or so. Shot it for the first time today, went through 75 rounds. Cleaned, greased, and oiled it before I took it out.

Also trying to remove or insert the bolt with the gun disassembled I can feel more resistance (pretty significant difference) when the bolt is about halfway into the upper all the way to being completely inserted.

Doesn't look like there are any obstructions...ideas? Was your bolt tight fitting new? Will the tightness just work itself out after break-in?

Thanks

[drpepper]

Mine has that exact
Problem on second time out.
Ended up being a magazine issue as pmags worked fine. Ended up taking apart the supplied asc mag and reversed the spring and so far no issues

[cc426]

I've got a pmag on order so hopefully that's it...but it was happening with 1/3/5/10 rounds loaded at a time...

Also the bolt feels abnormally snug in the upper... Going to try putting another 100 rounds through it tO see if that clears it up too...

[tal3nt]

Have you taken apart the carrier group?

[tal3nt]

If its anything like an ar15, maybe the extractor pin is off center?

[cc426]

Yes, took apart the BCG. Just took a look, extractor pin looks normal?

[FeuerFrei]

I've got a pmag on order so hopefully that's it...but it was happening with 1/3/5/10 rounds loaded at a time...

Also the bolt feels abnormally snug in the upper... Going to try putting another 100 rounds through it tO see if that clears it up too...

barring a problem with lube, mags, ammo it sounds like a gas system problem.
carrier or bolt should work nice and smooth. bolt should need a slight bump to go into battery on a new rifle without mag inserted & empty.
this should run right from the git go.


Sent with 2 cans & a long string.

[cc426]

barring a problem with lube, mags, ammo it sounds like a gas system problem.
carrier or bolt should work nice and smooth. bolt should need a slight bump to go into battery on a new rifle without mag inserted & empty.
this should run right from the git go.


Sent with 2 cans & a long string.

Yeah, bcg is not smooth within the upper, which makes me think there's a tolerance issue?