I have been increasingly interested in the .300 blackout as of recent but I don't want to spend another $1,000 on a gun at this point. I know I could get an upper and just put it on my AR lower so I don't have to buy a whole new gun. I then started reading about people who build there own. The upper sounds a bit more complicated and I would rather avoid that because I think there is something to be said for a good factory mil-spec built upper in terms of the quality it will provide.
It sounds like the lowers are rather easy to assemble though. I have no gunsmithing experience but it sounds relatively simple. Am I going to save much money if I assemble my own lower?

Anyone have any good recommendations on a good source for a good .300 blackout upper in terms of quality vs cost? And any recommendations on lower kits?

I would like to try out those short buffer tube designs to make a nice compact gun.

Dude if you can change the oil in your car you can build an AR upper.

I agree with GZ. The only thing that matters is torquing the barrel nut and head spacing. I myself recommend head spacing just in case in the future you want to make another 300 blkout upper or whatever plus it's a safety issue when mix matching parts. And you could always sell it after if you don't want it. My friend just made an ar upper in 300 blkout. He bought some quality stuff (billet upper, rainier arms barrel, failzero bcg, etc.) spent bout 900 including scope and mount.he kinda went cheap on the scope but I believe in Nikon . He did this during Xmas time so everything was on sale! Just shop around ..

Keep in mind 300 blkout had gas issues in the past but I think everyone oversizing the gas port now, so maybe not an issue anymore. His was .107 inches I think on carbine gas port length. He plans on supersonics only so I think he will be okay in terms of reliability.  He gonna use it on his colt lower.

Good luck! Remember, you pay what you get for..

I agree with GZ. The only thing that matters is torquing the barrel nut and head spacing. I myself recommend head spacing just in case in the future you want to make another 300 blkout upper or whatever plus it's a safety issue when mix matching parts. And you could always sell it after if you don't want it. My friend just made an ar upper in 300 blkout. He bought some quality stuff (billet upper, rainier arms barrel, failzero bcg, etc.) spent bout 900 including scope and mount.he kinda went cheap on the scope but I believe in Nikon . He did this during Xmas time so everything was on sale! Just shop around ..

Keep in mind 300 blkout had gas issues in the past but I think everyone oversizing the gas port now, so maybe not an issue anymore. His was .107 inches I think on carbine gas port length. He plans on supersonics only so I think he will be okay in terms of reliability.  He gonna use it on his colt lower.

Good luck! Remember, you pay what you get for..

Any recommendations on brands or sources for a lower kit?

Uhh for a lower.. Spikes, bcm, aero lowers all seem good. I actually scored on a spikes non painted Jolly Roger lower receiver . Paid 106.. But from other people across America said was that only 500 were made in the version I have. My serial number is under 500 so it may be true.  Cmmg makes lower parts kits in diff varieties such as with or without pistol grip etc. just in case a user wants a different one than an a2 grip. Go with a carbine buffer tube / buffer set up for 300 blkout. I was gonna make a 300 but decided x39 was my calling. Kind of a mistake but yeah. I spent countless hours reading setups online. If you can find one, I do recommend a pistol gas length barrel . I talked to noveske (dunno which tech out of the four they have but Kevin might have been his name, this was about a year ago) and he assured me his barrel can shoot subs and supers out of a pistol length gas setup. I concluded that he was telling the truth because more pressure in shorter time than of a carbine gas length would be able to cycle the bolt better. Always can add/ make your own buffer weights to smooth out action afterwards. Dunno the gas port size on noveske barrels though.

You honestly don't need a billet lower unless your going for looks. A regular forged in 7075 is good enough! Prob can get aeros for bout 80-90 bucks.

Some websites:
Midwayusa
Brownells
Primaryarms

Nothing fancy is needed for the lower. Good ol run of the mill milspec lower is tough to beat for the price. I honestly suggest just make an upper first. Ammo is expensive in 300 blk. And i highly doubt you wanna be shooting .75 cents-$1 a round for plinking . It is basically on same table as 30-30 hunting wise. Just swap uppers when you wanna hunt. Buffers too if needed. Everything is the same.

If I remember correctly a 5.56 has about 45k psi and 300 has an average 35k psi. That is weak in terms of the difference in pressure being generated therefore gas port is everything with this caliber. I suggest noveske, rainier arms barrels. Idk how good redx is . Ballistic advantage has a good reputation as well and that is what I'm using. Awesome customer service from black rifle arms.com. And when I say excellent I mean it. They located in Florida and he called me when it was midnight his time to help me with my headspacing issues. At first I thought my barrel was out of spec but it turned out to be my bolt. NIB coating made it thicker and that's why I failed at headspacing. He gave me all the specs I needed and helped me out. Sorry for ranting.

Watch mrgunsandgear on YouTube on barrel differences /selection. They come in all varieties and he can help you to find what fits your needs.

Dpms buffer tube
Dpms buffer
Cmmg lower parts kit without grip
Spikes lower (lmtd edition version I hope)
Magpul grip(it was laying around doing nothing)
Core15 trigger guard (looks cool with holes but not necessary to spend 12 bucks on it)
Geissele tricon trigger (not needed but I wanted it)

Those were the cheapest parts I found when I pieced my last ar15. Except the trigger haha. Wait for sales.. And you'll have more fun with it and save $$$.

Just buy a stripped lower locally. It may be cheaper than online unless your looking for something in particular. If you need to go cheap buy the rest online and wait for deals, free shipping or look for coupon codes. My scopes and red dots and higher end stuff usually never goes on sale so I pay what they asking for. Which is fine because I can't always have it my way . And I make up the loss by doing OT at work and saving pennies from other parts I need.

I have been increasingly interested in the .300 blackout as of recent but I don't want to spend another $1,000 on a gun at this point. I know I could get an upper and just put it on my AR lower so I don't have to buy a whole new gun. I then started reading about people who build there own. The upper sounds a bit more complicated and I would rather avoid that because I think there is something to be said for a good factory mil-spec built upper in terms of the quality it will provide.
It sounds like the lowers are rather easy to assemble though. I have no gunsmithing experience but it sounds relatively simple. Am I going to save much money if I assemble my own lower?

Anyone have any good recommendations on a good source for a good .300 blackout upper in terms of quality vs cost? And any recommendations on lower kits?

I would like to try out those short buffer tube designs to make a nice compact gun.

go see henry at prime sports hawaii
he has tons of knowledge about 300 blk
also got the powders you need to reload for it
and should have brass for sale within a week or so
he just came back from SHOT show, and should be getting a bunch of stuff that was ordered there
or he can line you up with what you need

good luck, and have fun
we have been shooting subsonic 300 blk since spring/summer last year
it's so fun to shoot
very little recoil and no supersonic "crack"

I agree with GZ. The only thing that matters is torquing the barrel nut and head spacing. I myself recommend head spacing just in case in the future you want to make another 300 blkout upper or whatever plus it's a safety issue when mix matching parts. And you could always sell it after if you don't want it. My friend just made an ar upper in 300 blkout. He bought some quality stuff (billet upper, rainier arms barrel, failzero bcg, etc.) spent bout 900 including scope and mount.he kinda went cheap on the scope but I believe in Nikon . He did this during Xmas time so everything was on sale! Just shop around ..

Keep in mind 300 blkout had gas issues in the past but I think everyone oversizing the gas port now, so maybe not an issue anymore. His was .107 inches I think on carbine gas port length. He plans on supersonics only so I think he will be okay in terms of reliability.  He gonna use it on his colt lower.

Good luck! Remember, you pay what you get for..

There are a fair amount of adjustable gas blocks out now.  I assume the uptick in supply has to do with the amount of suppressors now being available in 41 states.  Makes tuning up your upper a lot less difficult than even a couple of years ago.

I agree that adjustable gas blocks are handy. But I was talking about the gas port diameter being too small. Even though you may open the gas block to its maximum, there will still be a certain amount going through the gas port itself. Talking about restriction at the gas port. Syrac has a good rep of having an awesome gas block. It's 100 bucks or so.

A bad example: let's say your water hose has a diameter of 1 inch from faucet to end. Then you can add a 2 inch diameter pipe at the opposite end where the water comes out. The water that comes out will still be the same amount with a 2 inch diameter outlet. Or a quite better example would be an exhaust system and the back pressure vs free flow on a car. People put straight pipes for a reason to where the cat goes.

Anyways I think since 300 blkout barrel manufacturers have been upsizing it due to its growing popularity. Just get from a good source. I say 200-400 is well worth it.

Just my theory. From a good source (I think):300 blkout carbine gas port diameter for supersonics is .97 inches