80% 300 AAC Blackout Ar15 Build Complete

[DIY_2A]

I started this build with the plan of building a standard Ar-15, but found this kit and fell in love. I learned a lot from this rifle. Milling out the receiver was the hardest part with my uncles help and tools we completed the build start to finish in about 9 hours. I just wanted to share the outcome with you guys.

[Bzcraig]

Looks great and welcome aboard!

[DIY_2A]

Thanks now I am just waiting for a clear day to take it to the range to test. I am going to build a Polish AKM next!

[Blanco]

You will love the 300. I did not think my build would ever amount to much, but i have to say once you start shooting it you wont want to stop. I love shooting the 125~150 Gr supers. Extremely accurate. The more people that try a 300 the more will sell ... It is a winner

[wlc]

What 80% lower did you use? I've been trying to talk myself into doing one of these.

You will love the 300blk.

[DIY_2A]

I got my parts kit and 80% at Daytona Tactical. And I love it I put about 60 rounds though it of subs and supers, but I have problems with Failure to feed and double feeds any fixes I can do?

[DanishM1Garand]

Nice!
I like 80% builds.

[casac47]

Could be a number of things causing your feed failure. If you're not already maxed out, try loading your rounds a little hotter. You may not be making enough gas pressure to cycle the action. The double feeds are another thing all together. I'm going to guess that means your extractor is not fixing on the case or it may be tearing off the rim. When you manually release the bolt, does it always extract ?

[DIY_2A]

To fix the double feed I have to lock the bolt, drop the mag, and sometimes fish the stuck rounds out. the fails to feed I believe are magazine related issues, cause it has a pistol length gas system so pressure shouldn't be a problem.

[Tackleberry41]

Looks like the same stock on my 80% build tho I went with the full length, just prefer the rifle buffer to the carbine.

[wlc]

What mags are you using? Mine can be finicky with mags. So far 20 rounders, both metal and lancer(?)iirc, have always worked. 30 rounders have been a little more problematic. Metal mags have worked better for me than pmags. I haven't modified my mags in any way.

With a new rifle it will need to be broken in a bit. I hand cycled mine about 100 times before it finally smoothed out and ran. Another question: What bolt carrier are you using? AR15 or M16? Mine does better with the AR bolt carrier. Cant help with the double feeds though.

Were you having the FTF with the subs or the supers? Supers never have given me a hint of trouble, but subs can drive you nuts, especially if you have a 16 inch barrel with carbine gas. If you have any, try A1680 under a 230gr bullet. Use the published data by Hornady. Also, remember, with subs you start high and work your way down. I apologize if I'm preaching to the choir here, just spouting off stuff as I think of it that I mostly learned the hard way or after a lot of research.

[DIY_2A]

I wanted the full length, they were sold out and I didn't wanna wait longer.

Generic metal 10 round mags I sadly live in commiefornia so I cant test other mag capacities to see if that is it.
It uses a m16 bolt carrier. And I got FTF of subs and supers which is why I think its the mag. I was using 120gr supers and 220gr subs.

[mcdaniel.mac]

Double feeds and FTFs are both common mag-related problems. If you kkwo anyone else with a .300blk gun that runs, might borrow a couple mags to see is that's your issue. There's also a change that the lower is somehow wrong. Are you seeing a lot of wear on the feed lips?

[skeet1]

I got my parts kit and 80% at Daytona Tactical. And I love it I put about 60 rounds though it of subs and supers, but I have problems with Failure to feed and double feeds any fixes I can do?

I had big problems with feeding also in my .300 upper. I first polished the feed ramp and it helped just a little and I thought I would change magazines, I was using GI type metal ones. I went to PMAG gen 3 20rd. and it now feed perfectly. the 30 rd PMAG mags may work just as well, I don't know. I prefer the 20 rd mags for bench shooting off a rest.

Ken

[175lt2]

I've built 3 blackouts in the last year, 2 for me on Daytona tactical 80% lowers and an upper for a buddy. One of mine and the one for my friend are 17" barrels turned from green mountain 1-8" blanks both have carbine length gas systems, no feeding problems with subs or supers, the other rifle of mine has a 20" barrel 1-12" twist, it's a recycled Remington 700 take off it is for super sonic only, won't stabilize subs, this also has a carbine gas system. The common theme among them is the gas port its .125,,, yeah I know 1/8" seems huge for an AR gas port but they run fine I have adjustable gas blocks on mine and they are wide open and the rifles don't seem over gassed at all, I'm also using H&K 30rnd mags and 10rnd pmags, I do have feed problems with the standard GI mags

[Texas by God]

If you can get the ten round Magpul there- try that. Generic metal mags may be half or all of your problem.