what accuracy can i expect from a 11.5" and from a 14.5" bushy m4 barrel  1/9 twist using m193 ammos?   please help. thank u

Thats up to you, you dont loose noticable accurrecy with a shorter barrel, just velocity.

Quoted: Thats up to you, you dont loose noticable accurrecy with a shorter barrel, just velocity.

Bingo, but neither will work too well on bad guys.

Works if they are close enough and you are using the right ammo.  Mk262 will increase that range and make those lengths acceptable for CQB distances.

I've owned both, and if you're talking about the 11.5" barrel with 5.5" permanently attached flash suppressor, then I can easily suggest the 14.5".  The former is a little lighter, but that's it.

BTW, just in MY PERSONAL experience, my 11.5" barrel with 1:9 twist was under 3" at 100 yards with the 55gr stuff, but some GI 62gr SS109 was literally grouping 6" at 50 yards.  It was true GI stuff given to me by someone in service who had "collected it" and then never bought an AR.  Well, not given, I traded a Cold Steel Recon Tanto for about 1200 rounds of it, including 300 rounds of tracer.

Anyway, unless you're talking about an SBR, or unless you want the nostalgic look of a Vietnam era CAR15, I say go 14.5" with perm. flash suppressor.

11.5" Bushmaster, 1 in 7" twist, ACOG 3.5X. M885 ball at 100yds: about 1 - 1.5 inches  for 5 shot groups. I couldnt believe the first couple of groups but it shoots.  I know some will say no way but it does.

just curious, where did you get your m855?