Thinking of going with a AR 15 2O inch barrel.

[CoalCrackerAl]

Good video on different bullets in 1:7 twist. 55 does well considering. I'll know soon how mine does.
Watch this before you buy a 1/7 twist Ar15 - YouTube
1/7 vs 1/9 Twist Rate for AR15 - YouTube

 

[Varminterror]

“Overstabilization,” which has been debunked by many folks, including Bryan Litz, quite publicly. Don’t spin bullets so fast that they exceed their structural integrity, but overstabilization isn’t real.

 

[12Bravo20]

You never know how a 1-7 or 1-9 twist barrel will shoot with different weight bullets until you actually try shooting them. I have seen 1-7 twist barrels shoot 55Gr ammo well and have also seen 1-9 twist barrels shoot 69Gr ammo well. The weight of a bullet plays a part as does the length of the bullet.

The main reason that the military went with a 1-7 twist was due to the long 64 grain M856 tracer round. The M856 would not properly stabilize in a 1-9 twist in cold temperatures. Bullet manufacturers have since taken advantage of the common 1-7 twist for making heavier and longer .223 bullets.

 

[CoalCrackerAl]

Im looking forward to my new set up. Hope Fedex comes Monday. My M-lok bipod came today. As well as rings for the scope im putting on my 7.62x39. I wont get out until Tuesday to break and sight it in. If it does well with the 55 and 62 grain. I won't bother with the 69 grain bullets.

 

[ThomasT]

Good video on different bullets in 1:7 twist. 55 does well considering. I'll know soon how mine does.
Watch this before you buy a 1/7 twist Ar15 - YouTube
1/7 vs 1/9 Twist Rate for AR15 - YouTube

Thanks for that. I liked the video and was impressed with his 586 yard group from such a short barreled gun. I just built my gun a couple of weeks ago and haven't had a chance to shoot it yet. I just look at it a lot. It took me maybe an hour and a half to finish the lower. I thought it would be harder than it was. I bought a total of 3 lowers because the shipping and transfer was the same price. I will hold on to those other receivers for a future build.

My mother passed away March 28th after months of illness and instead of her affairs getting easier to handle they got even harder. Thats why I haven't made it to my buds land to try my new gun out. But I'm pumped about it.

I thought about ordering a 1000 69gr bullets from Rocky Mountain Reloading and may do it after I test my gun. I wish I could find a bulk buy of 62gr soft points instead. I would be all over those.

 

[IndianaBoy]

I have a DPMS Panther Lite with 1/9 twist barrel and just built my first AR from a PSA upper and PSA lower and carry handle. This one has the 1/7 twist. All the ammo and stuff to reload more ammo is all 55gr bullets. And I have thousands on hand. They work fine in the 1/9 twist but am not sure what to expect with the 1/7 twist using 55gr bullets. All the 20" ARs I am interested in and posted links to earlier all have 1/7 twist.

I haven't shot my new gun yet so have no experience yet on what to expect. How well do 55gr bullets shoot in your guns with the 1/7 twist? From the reading I have done they seem to shoot good but heavier might be better. All I am looking for is 300 yards at the most. The 1/7 twist on the retro ARs with 20" barrels has been a hold up for me.

55gr in a 1-7 twist will do just fine out to 300. In fact you would be ok to 500+ but wind deflection on the relatively low BC 55gr bullets will be your biggest problem beyond 500.

 

[DMW1116]

Thanks for that. I liked the video and was impressed with his 586 yard group from such a short barreled gun. I just built my gun a couple of weeks ago and haven't had a chance to shoot it yet. I just look at it a lot. It took me maybe an hour and a half to finish the lower. I thought it would be harder than it was. I bought a total of 3 lowers because the shipping and transfer was the same price. I will hold on to those other receivers for a future build.

My mother passed away March 28th after months of illness and instead of her affairs getting easier to handle they got even harder. Thats why I haven't made it to my buds land to try my new gun out. But I'm pumped about it.

I thought about ordering a 1000 69gr bullets from Rocky Mountain Reloading and may do it after I test my gun. I wish I could find a bulk buy of 62gr soft points instead. I would be all over those.

I've been loading a lot of different bullet/powder/primer combos for my 20" barrel lately. I have a PSA premium CHF FN barreled upper in A4 clone configuration. I put a scope on it to test some hand loads this weekend. I don't think you'll be disappointed. This target covers everything from 52 grain Barnes Match Burners (BMB) to 77 grain SMKs. The test loads with numbers on them are Shooters World Tactical Rifle and RMR 69 grain HPBT. The BMB and 22.6 grain groups are just under 1" measured, but I round to the nearest tenth, so 0.97" and 0.95" went up to 1.0". Anything less than 0.1" is too fine to even write down for me.

 

[LiveLife]

test some hand loads ... 52 grain Barnes Match Burners (BMB) to 77 grain SMKs. The test loads with numbers on them are Shooters World Tactical Rifle and RMR 69 grain HPBT

Thanks for the range report.

 

[DMW1116]

No problem. I haven’t had hand load testing work out this well in a long time.

 

[Varminterror]

Just to mention, when I started shooting Service Rifle ~20yrs ago, the guys mentoring me into it gave me a load for 55 ball over 27.3grn Varget to use as inexpensive practice ammo, even shooting this out to the 600yrd slow fire targets. I quickly stumbled into a high discount on 50 Vmax’s, and adopted the same charge under the new bullet. These were out of 1:7” twisted 20” A2 clones which were effectively required at that time for AR’s in SR. I’ve fired hundreds of thousands of rounds of this 50 V-max load in 1:7-1:14” 223/5.56’s, and loaded over 2m of them for customers while I was selling ammo for 3 gunners. No “overstabilization,” and no negative performance issues to report.

Surplus ball ammo, factory made, is as variable in quality as anything can be, but certainly isn’t representative of all bullets or all ammo sharing the same bullet weight.

 

[mavracer]

Good video on different bullets in 1:7 twist. 55 does well considering.

1:7 will do fine with 50s and 55s as long as they're good and concentric, they're spinning fast so if they aren't concentric they'll be fliers.
Many of the m193 55gr FMJs are crap and shoot accordingly. Steel core stuff often has similar problems.

 

[Bcwitt]

I put a green tip thru a 7" S&C channel (.490 web) w a 20", a 16" & an 11 1/2". The 20" blew right thru it & made a hole over 1/4" diameter. The 16" failed to penetrate. The 11 1/2" was predictably less penetration.

 

[mavracer]

I likey
I've been thinking real hard since the rule change to allow optics in service match of swapping to a flat top on my A2.

Thanks to your thread @CoalCrackerAl flat top upper and 1-4X Vortex inbound.

 

[Robert]

You never know how a 1-7 or 1-9 twist barrel will shoot with different weight bullets until you actually try shooting them. I have seen 1-7 twist barrels shoot 55Gr ammo well and have also seen 1-9 twist barrels shoot 69Gr ammo well. The weight of a bullet plays a part as does the length of the bullet.

My 20" 1:7 barrel shoots 55gr, 69gr, and 77gr bullets just fine. It hated the 62gr stuff I put through it. While it was not shotgun patterns, it was close. But that has been a while ago and I don't remember the exact ammo I used.

Now, it absolutely loves 77gr MK over 4064...

 

[12Bravo20]

@Robert, was the 62Gr ammo surplus M855, commercial XM855, or cheap foreign ammo? If so, your results don't surprise me especially if it was cheap foreign ammo.

 

[Robert]

I want to say it was one of the first two, but it's been a long time. The results were fairly awful so I just keep 55 and 77 on hand.

 

[mcb]

The old M855 bullet was notorious for bad accuracy. The steel core in the nose of the round is not controlled when the round is finally stuck in the manufacturing process locking steel core, lead plug and jacket together. This creates the potential that steel core can shift/tilt slightly throwing the balance of the rounds in flight off, opening up groups. This is part of the reason the new M855A1 has the steel core exposed at the nose, to ensure when the jacket is swaged the steel core is true and concentric with the rest of the round and by all account the new M855A1 is noticeably more accurate then the original M855, if a bit harder on the feed ramps.


Left: M855 Right: M855A1 projectiles.

My first AR was a Rock River Coyote Rifle with a 20-inch 1:9 twist H-bar. Great shooting rifle that is my primary 3-gun rifle. I have two other 20+ inch AR's but one is a 20-inch 450 Bushmaster and the other a 22-inch 30 Remington AR. Other than competition I don't use a 223/556 AR for much. Most of my AR are chambered in cartridges other than 223/556, 300 BO being of particular favor.

 

[12Bravo20]

Remember that the accuracy standard for the M16A1/A2 and M4 is 4 MOA at 100 meters. So even the M855 is within specs for military use. Most civilian shooters outside of range blasters won't accept or be happy with 4 MOA at 100 meters.

M855 is fine for breaking in a new rifle and for SHTF type scenarios but don't expect it to be very accurate. Now there are always exceptions to this too. My Windham Weaponry A2 barrel actually shoots M855 and Federal XM855 quite well. I always shoot full 5.56 ammo to break in any newly purchased or newly assembled AR before shooting any 223 ammo.

 

[redneck2]

And the dogs were out.

Ever think maybe this is why the driver didn’t stop? I have no idea how big your dogs are, but it could be a factor

Just sayin’

We used to have a member here that said he had vicious pit bulls. But, He said it was OK because he kept a stick handy so that if they were biting you, he could pry their jaws apart.

 

[CoalCrackerAl]

Ever think maybe this is why the driver didn’t stop? I have no idea how big your dogs are, but it could be a factor

Just sayin’

We used to have a member here that said he had vicious pit bulls. But, it was OK because he kept a stick handy so that if they were biting you, he could pry their jaws apart.

I keep them on a lead when expecting a package. They cant get within 12 feet of the gate. The UPS man spoils them lol. He always gives them treats.

 

[redneck2]

the guys mentoring me into it gave me a load for 55 ball over 27.3grn Varget to use as inexpensive practice ammo,

I have a friend that used to shoot High Power at Perry. He said Varget is never the wrong answer. My go to is 26.0 under a 50 grain Nosler BT, Federal SR primers, Winchester cases. With the Federal primers you don’t want to drop the bolt hard unless you’re stripping a round out of the mag

 

[JCooperfan1911]

20” would be next to useless for home defense.

Outside? It doesn’t do anything better than a 16” barrel until you’re talking several hundred yards downrange.

There’s a reason ALL the branches switched from the M16 series to the Colt M4.

The only application the 20” offerings have these days are for hunting and dedicated formal target shooting, or if you’re a collector and want to own a “musket” for nostalgia purposes.

 

[C-grunt]

The full size rifle is a bit more unwieldy in a building, but it's far from "next to useless".

The US military has handed out scores of dirt naps inside buildings with 20 inch eifles over the last 50+ years.

 

[CoalCrackerAl]

I like Varget too. It's dang expensive now.

 

[Robert]

Remember that the accuracy standard for the M16A1/A2 and M4 is 4 MOA at 100 meters. So even the M855 is within specs for military use. Most civilian shooters outside of range blasters won't accept or be happy with 4 MOA at 100 meters.

Oh absolutely, while my 77gt load is sub moa, by some miracle because I'm no expert reloader, at 100, I fully understand field accuracy. My experience was outside of even that generous tolerance. Heck, even my FAL shoot my plinking range loads was more accurate than those 62gr. But maybe I'll try to A1 and see if that is any better. At the very least it's a reason to go out and shoot.