AR 15 1 / 7 twist

[Left250]

Just purchased a Colt AR 15 with 1 in 7 twist in a 20" barrel. Being new at this, would appreciate help. Need to know the best ammo weight for this combination.

 

[tiriaq]

Best? It will shoot anything.
To cycle through the action, 77gr is likely the heaviest bullet you could use. 68 and 69 bullets would be fine, as would military 62s.
You can use the common 55s as well.

 

[mudgunner49]

Best? It will shoot anything.
To cycle through the action, 77gr is likely the heaviest bullet you could use. 68 and 69 bullets would be fine, as would military 62s.
You can use the common 55s as well.

...however if you load 40 grainers (uncommon i know) fast enough to work the action, you may get bullets disintigrating prior to reaching the target.

Ask me how I know...


blake

 

[jimy]

You just purchased a great rifle. Congrats. Tiriaq summed it well. Best of luck.

 

[ian_in_vic]

...however if you load 40 grainers (uncommon i know) fast enough to work the action, you may get bullets disintigrating prior to reaching the target.

Ask me how I know...


blake

You shouldn't shoot those in an AR or any semi-auto, there's no crimp on them (the Win white bow). The bullet can set back in the case making bad things happen.

 

[Janeau]

1-7 twist AR shoot better the 62-69 grains and heavier bullet... the change of twist to 1-7 was done to stabilize 5.56 rounds in that weight range.

For more info do a search on the web or start here : http://www.fulton-armory.com/

 

[Demon971]

Good acquisition! I own a Sabre Defence XR with a 1:7 rifling twist and 29.2cm barrel. Subcarbine shoots beautifully, and I find the best ammunition to fire would be 62gr. Generally the lower the grain, the better your grouping accuracy (marksmanship skills pending). However the 62gr is the median, and being used by military, would be a good bet to put your money on.

Currently I use AE 62gr. Expensive, but works decent. I wish I could get my hands on IVI rounds, but I've never seen it sold on civi market other than the casings for self-loading. Alternatively I use PMC.

 

[gushulak]

I have a 14.5 1/7 Sabre Defence that loves the heavy stuff, Hornady 5.56mm 74gr. BTHP T2's and Black Hills 77gr. BTHP.

I've shot every weight from 55-77gr. in my rifle and the heavy loads are decidedly more accurate.

 

[smak_daddy]

A 1/7 twist will stabilize any weight of bullet from 50 grains to 80 grains just fine. Period. Full stop.

If 1/7 AR-15’s won’t shoot lighter bullets, somebody forgot to tell that to all the AR’s I’ve owned over the years. I use 52 gr SMKs at 100 yards in my 1/7 ARs and they shoot fantastic. In fact my 77 SMK load shoots about the same, or a little worse than the 52 SMK at 100 yards.

If you are plinking under 200 yards, save your money and stick with 55 FMJ or 62 FMJ. They are cheap and they work just fine.

If you are shooting out past 200 yards, the heavier bullets will start to shine. The heavier bullets, like the 69 SMK and 77 SMK, shoot better at longer distances, not because they are any more inherently accurate than the lighter bullets, but because their ballistic coefficient (BC) his higher. One of the benefits of a bullet with a higher BC is that the effects of wind are reduced on the bullets flight path.

 

[mudgunner49]

You shouldn't shoot those in an AR or any semi-auto, there's no crimp on them (the Win white bow). The bullet can set back in the case making bad things happen.

Actually they did have a crimp on them as they were handloaded, as were some Federal 40gr Blitz varmint loads that I just recently got my hands on. While I've only fired about 60 rds of the Federal stuff I have put around 800 rds of the handloads thru 3 different AR's, one that was 1/12", and 2 that were 1/7/". The 1/12 worked great with excellent accuracy and crazy velocities (pretty close to 3600 fps) while both of the others appeared to shred jackets...

 

[ian_in_vic]

Ah, OK, handloads change the equation greatly, the only loads I've seen locally with 40 gr. are the dreaded uncrimped WWB.

 

[Driller]

It will be like any other toy in the closet that being a cartridge load the gun likes with the shooter matching well to it. 4-ARs later I realize factory loads can be all over the map just like anything else, along with hot or cold barrels playing as much as a strong breeze at distance. You should like the 1-7 twist a little better with heavier grain bullets as they mention in the previous posts.

Driller

 

[dangertree]

1-7 twist AR shoot better the 62-69 grains and heavier bullet... the change of twist to 1-7 was done to stabilize 5.56 rounds in that weight range.

Negative, the change from 1/12 to all the way to 1/7 was done to stabilize the long M856 tracer round.

 

[Airborn_69]

1:7 twist should be the standard!! Anyhow those Colts are really nice.

 

[Hadrian]

Surplus SS109 functions great.

 

[mudgunner49]

Ah, OK, handloads change the equation greatly, the only loads I've seen locally with 40 gr. are the dreaded uncrimped WWB.

Which I believe are 45 gr...

 

[emmab]

Surplus SS109 functions great.

If their is such a thing. Similar to unobtainium around here. I'm waiting to try my 1/7 colt with the 62 grain AE stuff($13.00 + tax/20 sigh)

 

[Paulinski]

1:7 twist should be the standard!!

Agreed

 

[lawn gnome]

I actually appreciate the fact that most barrels are in 1/9. They can shoot either 55gr or 62gr with pretty near equal facility. In the end ammo is whatever is cheapest.

 

[smak_daddy]

I actually appreciate the fact that most barrels are in 1/9. They can shoot either 55gr or 62gr with pretty near equal facility. In the end ammo is whatever is cheapest.

Ignorance is bliss.