AR-15 HELP!!!

[AYOxITZxACE]

Okay, so I got a 14.5" barrel (Yes, the flash hider is permanently attached) and it's stamped "5.56 NATO 1:9". Now I don't know too much about .223/5.56mm but all I know is that I've been shooting Federal XM193 (5.56mm 55gr. FMJ)'s out of it, and it works fine...

BUT HERE'S MY CONCERN:

Is there certain rounds I can/cannot shoot thru this barrel?

I read that certain rounds can damage or destroy the barrel from the inside like heavier 72gr., etc. I know they make different barrel ratios (1:7,1:9,1:12), so what rounds can I shoot thru 1:9?

Reason I ask is because Remington UMC .223 55gr. is more available than Federal XM193's in my area. I usually have to buy a bunch of little boxes or order in bulk online.

[yakmon]

It shoud shoot any commercially available ammo you can buy. Some will say bad stuff about steel cased ammo, but if the chamber is kept clean it's not a problem.

[AYOxITZxACE]

I don't shoot steel case b/c my range won't allow it. I was more concerned about the difference between .223 and 5.56mm, barrel twist ratio, and bullet grain.

[jshoebot]

If you have a 5.56 chamber, you don't have to worry about any .223 factory load. You're good to go with any commercially available ammo. A 1:9 twist rate is (arguably) good for almost any bullet weight, as it's between the 1:7 twist of the newer military barrels, and the 1:12 of older barrels. It will stabilize any 55gr bullet well enough, as well as the heavier weights. You're good to go with anything you want to put through it.

[yakmon]

They say that 1in 9 won't stabilize 77 gr and heavier properly. Now this won't damage your rifle, but accuracy won't be good. The differences between 5.56 NATO and .223 rem are insignificant with a 5.56 chamber. Your rifle should do fine with anything you're likely to find on a store shelf.

[sandnessj]

It is incorrect to think that you can shoot any commercial ammo out of a 5.56 barrel with a 1:9 twist. A 1:9 twist barrel will only control up to a 62 grain.

[AYOxITZxACE]

See, b/c in the Marines, all we ever shot was 62gr. M855 "Green Tips". Only thing stopping me from stockpiling that crap is the only outdoor rifle range in my area doesn't allow it! So I'm forced to stay with M193's (similar what the troops used during the Vietnam era. From what I read, the M193 was a devastating round, often maiming it's targets, so the gov't adopted the M855 not only because it was "more humane" but the steel core was excellent for shooting at targets behind soft cover and PPE (Steel helmets & body armor)

I could be wrong, but that's about all I know.

Also, that the M16A1's and XM177's had 1:7 barrels

[Pnguyen0216]

... Also, that the M16A1's and XM177's had 1:7 barrels

Correction M16A1 and XM177 Both E1 and E2 Series barrels were 1/12 twist. The 1/7 Barrels came out when the M16A2 came out in early 1980's.

Only Twist rates the US. Military ever had were 1/14, 1/12 and currently 1/7

[AYOxITZxACE]

I thought it was 1:9? Damn. Anyway, a few months back, I built my own M4 Carbine style rifle w/ DPMS 1:9 Chrome Lined barrel. Works like a charm tho. I can hit man-sized targets at the 500m like it's a habit but can't seem to hit 600m. Not yet anyway.

I think with a 1:9 twist, I should be just fine shooting 55gr M193s and 62gr M855 Steel penetrator rounds. I really don't have a need to shoot anything else. If I wanna shoot past 600, I'll just buy a Remington 700 in .308.

[yakmon]

It is incorrect to think that you can shoot any commercial ammo out of a 5.56 barrel with a 1:9 twist. A 1:9 twist barrel will only control up to a 62 grain.

77gr match ammo isn't commonly found on a shelf is what i meant.

[stitchnicklas]

figure out the barrel manufacture and they will tell you the grain limit for their barrel..

[AYOxITZxACE]

DPMS 14.5" Chrome-Lined 5.56 NATO w/ 1:9 Twist.

[diginit]

A 1:9 twist is good for 45 to 75gr bullets. Anything heavier or lighter will be inaccurate. Lighter that 45 will spin the jackets off the bullet and anything heavier than 75 will keyhole. Go to AR-15.com and do some reading. Keep in mind that if you change bullet weight, You may need to rezero.

[17+1]

They say that 1in 9 won't stabilize 77 gr and heavier properly. Now this won't damage your rifle, but accuracy won't be good. The differences between 5.56 NATO and .223 rem are insignificant with a 5.56 chamber. Your rifle should do fine with anything you're likely to find on a store shelf.

I think you're generalization is unfounded. Some heavy bullet weights from certain manufacturers may stabilize and some may not. I can't speak for any others besides the Sierras though. Have you personally shot 77grain SMK's out of a 1 in 9"?

Our 1 in 9" will hold slightly over 1 MOA with my 77 grain SMK hand loads.

[yakmon]

maybe i should, i've got a box of 77smk's on my desk, and a stag upper. no real need to though.