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Posted: 10/19/2025 3:29:13 PM EDT
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Looking to add another caliber to my stable for my AR. Currently have a 6.8 SPC Noveske / Vltor upper, and a 45 ACP Macon Armory upper. Looking at the 10.5" area, looking to do possibly 300 blackout or 223 / 5.56, for more "standard" ammo and magazines. What would be better for a "do all" round? With the BBB, suppressors would look to be an option in the future, so 300 blackout has a slight edge id eay, especially with sub-sonic round. Thoughts? |
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Fully agree. 300BLK is fun in subs and supers and with a short barrel is ideal in my mind, especially in the thickly wooded areas I live in. The rifle doesn't get hung up on stuff and I can't really reach out past 150 yards anyways due to the environment. You can shoot supers for the same price as 223/556 these days. Subs are still pricy but enjoyable. |
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Originally Posted By micmac: I concur. You need at least ONE 556 I like the 300 bo, but it's a niche round for sure. Originally Posted By micmac: I concur. You need at least ONE 556 I like the 300 bo, but it's a niche round for sure. Originally Posted By KentuckyMarksman: It sounds like you don’t have an AR in 5.56 / .223. In that case you need a 5.56. Originally Posted By osprey21: 223/5.56 |
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Originally Posted By sigman68: On the internet, I see 300 BLK recommened, but I rarely see it at the range. 5.56 is extremely versatile, target, plinking, defense, and hunting. It is also more accurate. My subsonic needs are solved with a 9mm upper. While 5.56 and 300blk ammo are closer in price, 5.56 will always have the advantage in "plinking/FMJ" pricing unless NATO goes deep into 300blk. Because of that, 300blk isn't really a range ammo in the AR platform (especially indoors). It is closer to 6.8spc or 300HAM'r or 350 Legend in that regards (I'm not including 6.5G because people use that for longer range shooting). If you are just putting holes in paper or shooting dirt piles, there is no real point in spending more money on ammo beyond function checking and zeroing. It isn't like the manual of arms is any different than 5.56. If OP does not have 5.56, he should have at least one upper available, but not a 10.5" IMO. 11.5", 12.5" (best .5) or 16" would be better. 10.5" length mentioned is/was normally a touch long for 300blk (8"-9" mo betta unless you really need the very slight increase in fps with a slightly heavier bullet), but the new NAS3 cases have flipped the script. I can't think of a cartridge/projectile/barrel length combination that has benefit more than 300blk in the 8"-12" barrel length range using the Barnes 120gr Tac-tx projectile in the NAS3 case. The Tac-tx projectile is the gold standard in 300blk, being that it was created specifically for 300blk with it's super low expansion floor. Given the limited case capacity, the 110gr version was always better than the 120gr version (especially out of short barrels) because the 120gr had a boattail that just took up too much case room. Box velocity out of a 16" was 2350 fps for the 110gr version and 2150 fps for the 120gr version. The 120gr version is actually better than the 110gr because it has a much slicker BC (.358 vs .289) and a slightly lower expansion floor (1300 fps vs 1350 fps), but didn't have the initial velocity to be useful out of short barrels compared to the 110's. I chrono'd them at 2250 fps out of my unsuppressed 10.5". Someone on YT chrono'd them at 2265 fps out of a suppressed 10.5" Even if a more realistic "full expansion" floor is about 200 fps higher, that is still full expansion at targets beyond what most of us civies would shooting 10.5" AR's at. Hard to beat that mix of projectile performance, energy on target AND expansion range out of a 10.5", while still being able to shoot subs with just a mag change. I'll add that the NAS3 cases look pretty interesting for the heavier 5.56 projectiles as well, especially 12.5" and up barrels. |
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