M&P .308

FRANKCASTLE · Oct 8, 2017

This rifle I just got isn't ejecting properly keeps jamming as a result. thinking of sending back to smith Wesson but I heard it would take 4 ever and a day , curious if someone could diagnose the trouble so I atleast have some idea of what iam trying to fix

Mike · Oct 8, 2017

Sorry I can't help you directly, but the guy who owns this IP business is very good at that type of thing. Maybe you can find some info there to help?

https://www.mdshooters.com/forumdisplay.php?f=227

Maryland Shooters > General > Industry Partners > Firearms Training
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d33rhunt3r · Oct 9, 2017

Is the empty brass stovepiping? What's the jam look like?

j_h_smith · Oct 9, 2017

A little more information and maybe someone can here can help you. Manufacturer of ammo, what grain are you shooting, how is it failing, etc? Pictures could also help a lot. Did you ad a little lube around the bolt or did you take it out of the box and shoot it like that?

Good Luck!

Sharpeneddark · Oct 9, 2017

I had some .308 AR problems, too. Chad (clandestine) and others helped me out in this thread: https://www.mdshooters.com/showthread.php?t=186766 I took a lot of pics and posted them.

Long thread short: The rifle is overgassed. The .308 AR platform is often overgassed, meaning there is too much gas going back to the bolt carrier and making it move too quickly. Gas blocks are designed for AR-15s using 5.56 rounds. The .308 gives a bit more gas than that. Replace your gas block with an adjustable one and adjust the gas operation as necessary. My AR-10's gas block is 3/4ths closed and operates like a dream.

Also, I added 3 or so quarters to the buffer tube, per Chad's advice. They are still in there to this day.

It may be similar to your problem, see if it helps.

Sticky · Oct 10, 2017

Sharpeneddark said:
I had some .308 AR problems, too. Chad (clandestine) and others helped me out in this thread: https://www.mdshooters.com/showthread.php?t=186766 I took a lot of pics and posted them.

Long thread short: The rifle is overgassed. The .308 AR platform is often overgassed, meaning there is too much gas going back to the bolt carrier and making it move too quickly. Gas blocks are designed for AR-15s using 5.56 rounds. The .308 gives a bit more gas than that. Replace your gas block with an adjustable one and adjust the gas operation as necessary. My AR-10's gas block is 3/4ths closed and operates like a dream.

Also, I added 3 or so quarters to the buffer tube, per Chad's advice. They are still in there to this day.

It may be similar to your problem, see if it helps.

This is very likely the problem. I built a 308 that had similar issues, overgassed and it too carries some spare change... :lol2:

lee2 · Oct 10, 2017

Send it back. Don’t screw up the warranty.

FRANKCASTLE · Oct 11, 2017

gonna go to the range take pics and " ILL BE BACK" was shooting 762.51 bucket a bullets. then 308 WIN. same issues

Sharpeneddark · Oct 18, 2017

Sticky said:
This is very likely the problem. I built a 308 that had similar issues, overgassed and it too carries some spare change...

Absolutely! It solves that problem effectively and there's no cheaper option!

FRANKCASTLE said:
gonna go to the range take pics and " ILL BE BACK" was shooting 762.51 bucket a bullets. then 308 WIN. same issues

Any results? What range do you go to? If you're around Westminster, or go to Hap Baker, I'd be happy to join you and help troubleshoot it. I'll even bring my AR-10 and some 308 ammo.

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