Well piecing together one may be a big leap, there are some tools specific to the AR that are useful. You can get by with just an AR armourer's wrench and upper receiver vise block, but a gas system alignment tool is handy for the upper receiver. And I would always recommend using a torque wrench on the barrel nut. A good punch set is necessary and obviously a hammer, a magwells vice block can be useful for the lower receiver. YouTube and such can teach you everything about assembly. It's very easy and just like playing with Lego's as a kid.
Now brands. Where to begin. The market is absolutely flooded with components. From cheap to ridiculous. I personally lean towards the buy once, cry once, go cheap you'll weep mentally. You do not have to get the most expensive, because half the time you're mearly paying for the name. And so many of these components are made in the same factory, named, and sold to guys saying "Seekins rings are better than Vortex." [emoji23] Buy American, veteran owned in the middle price range. For the amount of shooting it sounds like you'll be doing, you'll be fine. Honestly it sounds like buying a complete upper and lower separately that you like may be the best route. The 300 BLK can be a finiky AR. Especially when shooting subs suppressed is an end goal. May not be the best to start as custom build. Took me over a year to develop a well rounded subsonic load for my 8.5" 300 BLK pistol. With heavy modification to both the load and firearm.
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