S&W M&PT upgrade

AR/M4 AR General Discussion
1

OK guys, I’ve learned alot since I purchased my AR. I have changed out the weak components with higher grade pieces, the things I’ve “fixed” are:

  • Replaced stock to LMT SOPMOD
  • Replaced buffer with a H2 buffer
  • Replaced bolt group with a BCM bolt group
  • Replaced pistol grip with a Hogue

I also added other stuff that dont relate to reliabilty… flashlight, sling, Eotech, ETC…

The question is, the last of my upgrades would to replace the upper with one that have M4 feed ramps and a mil- spec barrel (LMT or BCM)… Would you guys advise me to upgrade or leave it as is?

Thanks for your help
Bri

2

I wouldn’t replace the barrel until it’s accuracy goes (from bad throat erosion) or it no longer headspaces. More than likely you won’t need M4 ramps.

3

I’d shoot the upper until it fails.

If you have a want or need to use long 75-77 grain ammo and your M&P won’t stabilize it, you could buy a separate/new upper.

4

Bri, I’d be interested to know how the H2 is working in your S&W – what ammo, round count, any failures before or after the swap, etc.

One of the pros here suggested that I swap for an H buffer on my M&P 15 (base model), and that’s what I intend to do, but I’m curious about the H2.

5

An H will work just fine. An H2 could short stroke with weaker ammo (.223 not 5.56mm NATO). I typically only use H2s in SBRs under 14.5" and H buffers in everything else. My Colt 6920/6721 ran fine for 500 rounds with an H2, this 6920 upper is currently getting the Primary Weapons piston kit installed on it with a Daniel Defense 9.5 FSB rail. I’ll try different buffer in it for function and to see how it feels.

The H2 in the Colt made it feel softer/slower than it did with an H buffer. With the H2 it would occasionally short stroke (eject but not pick up the next round in the mag) with Radway Green ammo, no problems when using an H buffer with Radway.

6

That’s exactly what I was wondering about, gotm4 – thanks.

It unsettles me a bit that I’m starting to understand this stuff…:smiley: