Will a 1:7 barreled AR shoot a standard 5.56 55 gr bullet well? [Archive] - Glock Talk

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WarEagle32
07-04-2012, 21:12
I have a 1:9 M4 that I have shot 55 grain bullets through very well for years. I am seriously thinking of buying another AR thats a top tier M4 which has a 1:7 barrel. I have a ton of 55 grain 5.56 stored up. I know the 1:7 will shoot 62gr green tips well, but does it also do well with 55's because I don't want to have to buy more separate larger ammo anytime soon. Thanks for any info!

Zombie Steve
07-04-2012, 21:18
Shoots 'em just fine.

WoodenPlank
07-04-2012, 21:18
I have a 1:9 M4 that I have shot 55 grain bullets through very well for years. I am seriously thinking of buying another AR thats a top tier M4 which has a 1:7 barrel. I have a ton of 55 grain 5.56 stored up. I know the 1:7 will shoot 62gr green tips well, but does it also do well with 55's because I don't want to have to buy more separate larger ammo anytime soon. Thanks for any info!

Some people will swear up and down that they got crap accuracy from 55gr with a 1/7 barrel. I've owned several (16, 14.5 and 10.5) 1/7 barrels that were plenty accurate with 55 grain ball, especially federal in various forms. 2-4 MOA is typical, but I have seen as good as 1MOA. My 10.5 SBR will shoot better groups than I will ever get with my 4MOA Aimpoint with Federal XM193.

As usual, YMMV etc...

Sent from the USS Sulaco, while nuking the site from orbit.

arclight610
07-04-2012, 21:19
My 1/7 shoots 55gr just fine. In fact, I use 55gr almost exclusively.

Decguns
07-04-2012, 22:05
The 55gr FMJ will shoot fine in a 1-7 twist. Under 300 yds, you'll never notice that it's over-stablized. The faster rifling twist actually increases penetration on hard targets like car bodies and GI helmets just like it does for the SS109.

The only problem I've ever had with 55gr ammo in a 1-7 is shooting soft points at velocities over 3200 fps. The projo is spinning at 300,000+ RPM, and light skinned varmint projectiles can literally self destruct after leaving the barrel. About 3 feet from the muzzle of my Colt HBAR, I'd see a little black puff ball where the projo blew apart.

Zombie Steve
07-04-2012, 22:12
The 55gr FMJ will shoot fine in a 1-7 twist. Under 300 yds, you'll never notice that it's over-stablized. The faster rifling twist actually increases penetration on hard targets like car bodies and GI helmets just like it does for the SS109.

The only problem I've ever had with 55gr ammo in a 1-7 is shooting soft points at velocities over 3200 fps. The projo is spinning at 300,000+ RPM, and light skinned varmint projectiles can literally self destruct after leaving the barrel. About 3 feet from the muzzle of my Colt HBAR, I'd see a little black puff ball where the projo blew apart.

Good point. I wouldn't go with varmint bullet construction or anything lighter than 50 grain bullets.

APERS
07-04-2012, 23:10
55gr works fine in my 1-7" (BCM),, out to around 200yards or so. Also own a 1-9'' Stag that I loaded alot of 52gr BTHP (Nosler) Match bullets for..which I tried the other day while zeroing BCM at 50 yards. They actually grouped tighter than the 68, 62 & 55 gr bullets! Im starting to believe that quality of bbl in an AR has alot more to do with accuracy than twist rate..?? As a side note, both rifles will group the best with 64gr Win. Power Point bullets. At 50 yards that is.. boat tail bullets with excel at longer ranges as a rule of thumb. 250yds and beyond.

WarEagle32
07-04-2012, 23:14
Good point. I wouldn't go with varmint bullet construction or anything lighter than 50 grain bullets.


Interesting because I use TAPs and ballistic tips a lot! However pure copper Barnes TSX's are by far my favorite!

SCSU74
07-04-2012, 23:22
I have a 1:9 M4 that I have shot 55 grain bullets through very well for years. I am seriously thinking of buying another AR thats a top tier M4 which has a 1:7 barrel. I have a ton of 55 grain 5.56 stored up. I know the 1:7 will shoot 62gr green tips well, but does it also do well with 55's because I don't want to have to buy more separate larger ammo anytime soon. Thanks for any info!

Xm193 works great out of my 6920 1/7 out to 50 yds. It works less great I further out I go. At 100 it hits very low and right. Switching to 62g duty ammo at same distance hit dead on. Ymmv


Sent from my iPhone... which probably auto-corrected something wrong

AustinTx
07-05-2012, 00:15
The only problem I've ever had with 55gr ammo in a 1-7 is shooting soft points at velocities over 3200 fps. The projo is spinning at 300,000+ RPM, and light skinned varmint projectiles can literally self destruct after leaving the barrel. About 3 feet from the muzzle of my Colt HBAR, I'd see a little black puff ball where the projo blew apart.

You have noticed something that most gun owners won't believe. Until you do the actual calculation, most people won't believe the bullet is spinning that fast. My son-in-law found that out with light bullets in a 25-06.

Redfire SVT
07-05-2012, 00:26
Depends on who you ask! But, IMHO, it will shoot them just fine.

AustinTx
07-05-2012, 17:16
Depends on who you ask! But, IMHO, it will shoot them just fine.

Well, I didn't ask you, anyway.

Redfire SVT
07-05-2012, 17:30
Well, I didn't ask you, anyway.

I was referring to the OP, who asked for my reply just as much as he did yours. Thanks!

AustinTx
07-05-2012, 23:49
I was referring to the OP, who asked for my reply just as much as he did yours. Thanks!

Please excuse me. I don't know what I'm doing most of the time, anyway. I just come here to have fun and maybe even learn something.

Tiro Fijo
07-06-2012, 01:19
Interesting because I use TAPs and ballistic tips a lot! However pure copper Barnes TSX's are by far my favorite!


The rate of twist formula is really for bullet LENGTH and not weight, hence your Barnes SC bullet being longer (copper less dense than lead) should do fine.

Haldor
07-06-2012, 12:21
Works great. That is how my Colt AR15-A2 is barreled (1:7) and all I shoot through it is M193 ammo. I am getting 3" groups at 100 yards with this combination.

eracer
07-06-2012, 12:24
I have an 18" 1:7 middy that shoots 1 MOA with 75gr TAP, but only 5 MOA with 55 gr. M193. My 1:9 carbine shoots both M193 and 75 gr. Hornady Match to 1 MOA.

Point is, different barrels handle different ammo differently.