Range Report 223, 75 gr, 10 1/2” AR Platform
- Thread starter krw
- Start date
Somewhere between 2400 and 2550 is my bet. Because of the slow velocity achievable out of such a short barrel I recommend a 1 in 7 rifling at the very least to make sure the bullets are spun fast enough.
A 1 in 6.5 would be ideal but those are custom jobs.
A 1 in 6.5 would be ideal but those are custom jobs.
This is my MK12 Mod K. 13.7 Noveske barrel with the AEM5 suppressor. It does 77grn at 2550 FPS. 75grn PPU match was 2475 avg but its really light load...
I've had it out as far as 712 yards accurately and put 16/20 on a 14x20 inch plate at 554 yards in a 18mph wind.... short barreled 223 is better than people think... then again so is 308, 6.5 etc....
I've had it out as far as 712 yards accurately and put 16/20 on a 14x20 inch plate at 554 yards in a 18mph wind.... short barreled 223 is better than people think... then again so is 308, 6.5 etc....
I'd plan on 2350fps from a 10.5" barrel, though you could be 50fps either side depending on your barrel, powder, and tolerance for pressure.
Man that's way slower than I had guessed. Without running any stability calculations I'd say 1 in 7 would be the bare minimum rifling.
Sea Level
32F
29.92Hg
Hornady 75gr HPBT @ 2350fps
Stability factor 1.25 @ 1:9 twist
8 twist is 1.59, 7 twist is 2.07
32F
29.92Hg
Hornady 75gr HPBT @ 2350fps
Stability factor 1.25 @ 1:9 twist
8 twist is 1.59, 7 twist is 2.07
I haven't shot the 75s, but I get right at 2300fps out of my 10.5" with a stiff varget load pushing 77g SMKs.
Same load gives me 2730fps in an 18".
Same load gives me 2730fps in an 18".
I had a 10.5” 5.56 barrel...I now have a 12.5” Ballistic Advantage 5.56 barrel.
LOVE the 12.5, noticably less harsh than the 10.5 IMO and I don’t notice the extra length.
Have not chronographed my Mk262 clone load (77gr Nosler over 23.5gr 8208XBR) but am using 2450 as a swag. I can push to 23.8gr for a bit more speed, but it isn’t worth the accuracy trade.
LOVE the 12.5, noticably less harsh than the 10.5 IMO and I don’t notice the extra length.
Have not chronographed my Mk262 clone load (77gr Nosler over 23.5gr 8208XBR) but am using 2450 as a swag. I can push to 23.8gr for a bit more speed, but it isn’t worth the accuracy trade.
Heavies using slower powder is not ideal in short barrels... unless you are trying for subsonic, then you are better off with. 300 blk.
I agree with using lighter pills in the short barrels.
For the most part (and for full disclosure, I use mk262 clones in my rifles) the 75-77 grain projectiles don't really show their advantage until after 5-600 yards. Unless you are anticipating those long shots, 55-62 grains is the sweet spot. 69 grain smk is a really good compromise. I really like the way smk's will frag at lower velocities. However, they are not barrier blind.
I think a really good short barrel round is the Speer 55gr gold dot factory loads.
I agree with using lighter pills in the short barrels.
For the most part (and for full disclosure, I use mk262 clones in my rifles) the 75-77 grain projectiles don't really show their advantage until after 5-600 yards. Unless you are anticipating those long shots, 55-62 grains is the sweet spot. 69 grain smk is a really good compromise. I really like the way smk's will frag at lower velocities. However, they are not barrier blind.
I think a really good short barrel round is the Speer 55gr gold dot factory loads.
I prefer the 64gr Gold Dot, which gave me surprising velocity (close to 2700FPS, if memory serves) from a suppressed 10.5" barrel.
If my TBAC dsu ever gets out of jail I plan on using 75’s I bought some of the hornady 5.56 sbr loads to try. This is a dedicated pig, coyote gun so not really worried about long range but should be good out to 200 or so
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