https://www.thehighroad.org/index.php?threads/thoughts-on-tools-after-first-ar15-build.892161/ Since I recently bought an AR15 rifle in 5.56/.223, I decided to build an AR15 pistol in 300 blackout. My goal was to get some experience building a complete AR15, try out various tools, and see what all the fuss is about . I wasn't trying to build the best/cheapest/etc. Also, I was somewhat constrained by what parts were available. Triggers and BCGs were especially hard to find. Lower receiver: I bought an Anderson lower with an American flag etched on the left side for ~$80. I've seen the "all that on an Anderson?" comments, but to my eye the quality seems quite good. I'm happy with the product (but see below re. issues I had fitting a drop-in trigger). SBA4 brace. Bought on deep discount. I like it; I hope I get to keep it. BCM Gunfighter Mod-3 grip. I have a B5 grip on my other AR15 and like the shape of both, but I like the less aggressive texture of the BCM grip. With gloves either would be great. Lower parts kit and buffer tube assembly kit. I bought more upscale kits (spent around $200 w/o fire control) and probably should've just gone with cheaper options. The kits did come with B5 trigger guard and grip which are nice, and an end plate with QD mount. I'm using Magpul 300blk gen3 30 round magazines, and will buy the 20 round version as soon as they're available. The complete lower was easy to assemble, except for two areas: bolt catch pin and drop-in trigger. The bolt catch pin just needed a long roll pin starter punch so that I could get enough clearance past the end of the receiver to get the pin/punch/hammer lined up and held securely enough to get it started. The drop-in trigger was a bigger issue: I'm using an ELF trigger that didn't fit in the Anderson lower. The problem is that the pocket in the lower has large radius corners, so the pocket starts to turn in less than 1mm too soon to fit the square profile of the ELF trigger housing. Online, I saw a lot of comments about filing down the trigger housing, but I chose to abuse the $80 lower instead of the $260 trigger . I used a dremel with drum sander bit to etch out a little material from the front corners of the trigger pocket. Do other lower receiver brands have more squared-off corners in the trigger pocket? Here's the lower receiver during the build, and a photo of the abused trigger pocket: For the upper receiver, I bought all the parts from Odin Works, including their billet upper receiver w/o forward assist, 10 1/2" barrel, adjustable gas block upgrade (plan to run this suppressed), and O2 Lite forend. The Odin Works components are very nice. They have a different system for attaching the barrel and forend, which uses a forend adapter that threads onto the upper receiver, and a separate barrel nut that screws into the other side of the adapter. They have a machined pin to align the adaptor to the gas tube hole while tightening the barrel nut. Here's a video: I've seen comments about buying complete uppers instead of building, but the upper was actually simpler to build than the lower. Maybe the advice applies more when mixing and matching components from different sources. I finished off the build with a small hand stop from Lead Faucet Tactical and iron sights from Scalarworks. The Peak iron sights are gorgeous! Of course, you could get a red dot cheaper. Here's the final result. Hope to test fire it tomorrow and get it sighted in. Overall, this was a lot of fun and I have a much better understanding of the AR15 platform. The only downside I see to building your own is that resell is likely much less than for an off-the-shelf gun.