Building an M&P15 lower

[crracer_712]

I've had the M&P 300 tactical upper for quite some time, swapping it with my M&P15A lower when I want to shoot it. I decided to build a lower so this upper can have a home. I've ordered a M&P15 Stripped lower, and I have some ideas of some of the parts I want to put in this lower, such as the Spikes Tactical buffer tube kit, a Magpul Moe + grip, a 2 stage trigger and most likely a Hogue butt stock.

I'm a little torn on what pins and springs kit to buy, one that might include the mag catch assembly and the Bolt catch assembly. I know there are quite a few parts kits out there with just these parts in them, but I'd like quality parts. Would appreciate any input on quality parts, could even be a DPMS parts kit if anyone has experience with those and know they are good.

One place that looks interesting is Red Barn Armory where they allow you to assemble your LPK starting with basically
the pieces I'm looking for and upgrading things such as the trigger guard, grip, etc so you don't end up with a bunch of duplicate stuff a person isn't going to use. I just don't know of the quality of the pins/springs that RBA sells.

 

[jagular]

Palmetto state armory has parts kits as well. If you want anti rotational pins go for kns. They may also have other lower parts as well. I've never had a problem with trigger pins walking out. Never heard of RBA.

 

[Rastoff]

I've built several lowers. I have many thousands of rounds through the resulting guns. This however, "I just don't know of the quality of the pins/springs that RBA sells" is nothing to be concerned about.

I mean, if you want a good trigger, buy a Geissele or Timney. Or you could upgrade the standard MIL-SPEC trigger with the 15 minute trigger job. But, there's absolutely no reason to worry about the "quality" of the pins and springs.

I'm sure some are better than others, but you're not going into combat in the most remote areas of the world. Every pin and spring out there will be fine.

 

[spad124]

I assembled my first lower last weekend. Nothing fancy. A modified US GI LPK into a McKay lower for a Vietnam retro AR. The seller made all the AR mods to the Colt LPK and changed out the trigger for a RRA. All I did was assemble. The trigger is heavy, but there is no creep. So, you can get a decent trigger with a basic LPK.

 

[crracer_712]

Palmetto state armory has parts kits as well. If you want anti rotational pins go for kns. They may also have other lower parts as well. I've never had a problem with trigger pins walking out. Never heard of RBA.

Checked them out, got what I needed without too much waste and most of it was on sale, shipping was reasonable too. Thanks for the reminder that they sell this sort of stuff

 

[crracer_712]

Impressed with PSA so far, placed the order a couple hours ago and already have the tracking information. Can't believe I hadn't delved deeper in to their website before. I'm thinking I might have to have my FFL fax a copy of his license to them for future use...

 

[scooter123]

I've built two rifles with the CMMG Builders Kit purchased from Midway. Because this kit doesn't include the Fire Control Group you get only what you need if you are using a separately sourced Fire control Group. BTW, I've used the Single Stage 3 lbs. Timney drop in trigger on both of my builds and just do NOT understand why anyone would actually use a 2 stage trigger on a fresh build.

 

[noscivic]

I've built two rifles with the CMMG Builders Kit purchased from Midway. Because this kit doesn't include the Fire Control Group you get only what you need if you are using a separately sourced Fire control Group. BTW, I've used the Single Stage 3 lbs. Timney drop in trigger on both of my builds and just do NOT understand why anyone would actually use a 2 stage trigger on a fresh build.

I was going to suggest this. These are what I use, but get them from Primary Arms. Why buy a complete kit when you end up not using a lot of it and pay for it.
Gary

 

[crracer_712]

I've built two rifles with the CMMG Builders Kit purchased from Midway. Because this kit doesn't include the Fire Control Group you get only what you need if you are using a separately sourced Fire control Group. BTW, I've used the Single Stage 3 lbs. Timney drop in trigger on both of my builds and just do NOT understand why anyone would actually use a 2 stage trigger on a fresh build.

That's a woman statement right there! Their way or the highway, no concept of preference

 

[crracer_712]

Got all my parts from PSA, had also ordered spring and pin kit from Amazon (excellent kit!). The kit from Amazon was a God send in that it included two tools to assist in installing the front take down pin detent and spring (all for 21.99). The parts from that kit looked great, but I did use the PSA parts kit I ordered. Also used the PSA buffer tube kit which fit and finish were excellent. Assembled easily, found out my Pro Mag lower vise block would also double as a trigger guard backing for driving the pin in the Trigger guard assembly. Everything fit and functioned perfect, my 300 whisper/AAC Blackout upper has a home of it's own now.

Paid a little more for the M&P15 lower, but preferred it as my upper was Smith & Wesson as well.

Lower 134
Buffer Tube kit 30
Lower parts kit with MOE grip and trigger guard 45 (no FCG)

Just stuck on the standard stock that I had lying around and used the FCG I had pulled from my Colt LE6920 (of my mil-spec FCG's it was the lightest pull rate, and after installing it's around ~6.25 lbs.)

 

[crracer_712]

My finish M&P15 lower using PSA Buffer Tube assembly, PSA pin and spring kit (it included the Mapgul grip), Magpul enhanced lower trigger guard, Trigger from my Colt LE6920, after a little cleaning up it is ~6lbs. Upper is the Smith & Wesson 300 Whisper'/300 AAC Blackout