Been lurking for a while, spent the last 3-4 days reading EVERY NFA post in this forum and have not found any similar questions. I’m an SBR newbie, but I’ve been trying hard to get up to speed on everything.
I’ve got a built S&W M&P 15 that I am considering registering as an SBR lower. I live in NC, which presents a substantial barrier to private ownership, but I have the support of my local CLEO, who has assured me he will sign a Form 1 for me.
I’d like to use my lower as it is for a my SBR. Ideally, this would just involve getting the lower engraved and registered and then buying a complete short-barreled upper. However, I know the M&P has some slightly different dimensions from a 100% mil-spec lower (ie, cannot use an accuwedge due to higher shelf height), but are the differences enough to make a factory mil-spec upper (Noveske, LMT or BCM, for example) verboten? I’m going to buy a caliper this weekend and check the takedown holes and magwell for spec.
As it stands now, I’ve got the 16" stock barrel with F-marked FSB. I’d like to transition to a low profile gas block and run a longer handguard on my SBR upper. Would just buying a 10.5" or 11.5" barrel, gas block and handguard be better than a complete new upper? I’d like to re-use my lower so I don’t have to buy another stock/end-plate sling adapter/etc, etc.
Has anyone SBRed a S&W M&P 15? Any difficulties? Any comments to make the process easier? I believe I’m leaning towards the 10.5" - 11.5" length, with 9.0 or 10.0 rail. Any changes needed to the buffer or spring? I BELIEVE that the M&P has a carbine buffer and carbine-length gas system.
I’m not fortunate enough to have a job that allows me to shoot dangerous bad people in the head from handshake distance, I just want a more suitable HD rifle / range toy / carbine class rifle.
Thanks in advance for all the help, I’ve already learned a ton.
W