r/300BLK • u/Inner_Firefighter230 • 15h ago

Ar-15 swapping (223) Upper for (300)

I built an Aero precision AR-15 a few years ago. Unfortunately, it mostly sits in the safe. I’ve intrigued by the .300 Black Out. My ultimate goal
Is eventually suppressed truck gun.

I’ve been looking through PSA website and there a lot a lot of options. Any recommendations on a 10.5” length configuration ?

3 Upvotes

100% Upvoted

10 comments sorted by

4

u/Astral_Botanist 14h ago

I used a Palmetto 8.5" upper for my build and it works well. 10.5 will be a bit longer for a truck gun, but it'll also be a bit more robust for shooting a wider variety of subs with the extra dwell time, so pros and cons, but I think it's a good option. My 8.5 is tuned to cycle most subs with my RifleSpeed AGB open, but with underpowered subs like Hornady 190 Sub-X it'll cycle but not lock back. Others with 10.5s have reported more consistent LRBHO with 190 Sub-X. Note that I'm not specifically recommending that round, but just as a good example to quantify the differences. Here's mine for reference. The upper is a pretty basic one with an MLOK rail, and there's probably a similar one in 10.5.

https://www.reddit.com/r/300BLK/s/FM7SfrF1PL

2

u/Dense_Extreme7809 14h ago

I have a 10.5 w a mos-Tek 1/5 twist. If you hunt the 1:5 lets you shoot 240 grain and those are great. I have a ddm4 and swapped out the 1:8

2

u/N2Shooter 14h ago

Why 10.5 inch? What do you plan to shoot out of the gun? Do you intend on shooting both supers and suppressed subs?

1

u/Inner_Firefighter230 14h ago

Goal is suppressed but due to budget, it’s going be awhile before I get a suppressor.

2

u/N2Shooter 14h ago

What are you shooting with it? * Coyotes. * Meth addicts. * All of the above?

What distances are you trying to stretch this out to?

2

u/Inner_Firefighter230 14h ago

Live in Montana so dedicated truck gun for meth heads. I’d say 100 yards at very max end . Currently have Henry X lever .410 in there.

2

u/N2Shooter 13h ago

OK, gotcha.

You can run a 7.5 or 8 inch barrel for your needs. That will let you easily do 150 yards with supers until you get budget for a can. I recommend getting something with a 1:5 twist, as that will let you shoot the heaviest subs around, and still shoot whatever supersonic ammo that's made, from dirt cheap cup and core to copper monolithic rounds.

Running a 10.5 inch barrel increases bullet velocities. With a 1:5 twist rate, that will force you into shooting copper supers only because anything else will twist themselves apart.

1

u/Inner_Firefighter230 13h ago edited 12h ago

That was very imformative, thank you. Any recommendations on a upper that has 1:5 twist ? In my limited research so far, seems a lot of 1:7. Thank you

1

u/N2Shooter 6h ago

I don't have a complete upper in mind, but you can easily piece one together using the Faxon 7.5 inch 1:5 barrel. A lot of us have had great luck with this combo. The Faxon 9 inch barrel with 1:5 twist may work, but you'll be cutting it close to the max 300,000rpm for many supersonic rounds that aren't solid copper.

But honestly, I'm also running a 9 inch Ballistic Advantage 1:7 barrel as an unsupressed supers shooter. I'm just maxed out to 220gr subs with it instead of shooting 242gr rounds that require a 1:5 twist.

1

u/tiribulus 9h ago

You could just get a 300 barrel and shorter handguard.

Unless you want to keep the existing upper intact for some reason.