1-7 Twist Issues

[Joe D]

Has anyone had a problem shooting 55 gr bullets with a 1-7 twist barrel. I can't get any kind of group with several different brands of ammo. I am talking about 3"+ groups at 50 yds off a rest with a good scope.

One of my other uppers with a 1-9 twist shoots sub-MOA groups at 200 yds with the same ammo.

I realize a 1-7 is not ideal for a 55 gr bullet, but it should shoot better than 3" @ 50 yds. I am starting to think there is something wrong with this upper.

[L9X25]

How does it shoot the heavy projectiles? I would test a few before I passed judgement on the barrel/upper.

[smokshwn]

+1 to testing a heavier bullet.

If it won't shoot 69's or 77's then I would worry.

[Derek45]

My 1:7 COLT shoots 55 gr Very well.

[johnhurd]

My 1-8 does the same thing but loves the 75 Hornadys

[Joe D]

I have some 69 gr bullets I will try in a couple of days.

[Guy Neill]

Much will depend on the bullet. The high RPM resulting from the fast rifling twist and high velocity will blow up bullets that are too frangible. Even if hte bullet holds together, any imperfections in the bullet construction will be magnified. Things like the jacket thickness variations.

Guy

[uscbigdawg]

Hey Joe,

My 1:7 Colt shot 55's okay. Loved the heavier bullets. My 1:8 gobbles everything and why I loooooove that rifle so much.

That said, while it's not a hard & fast rule, the 1:7 twist will tend to like heavier bullets more than the lighter ones. Like Guy said above too, it can depend on the bullets.

Bottom line, try some 68gr. Hornady's, 69gr. & 75gr. SMK's and let 'er rip.

Rich

[Mr. Chitlin]

I use a 1/7 Bushmaster, and it shoots 55 grain Ballistic Tips under MOA. More than good enough for me for 300 yard plates.

[Joe D]

I tried some of my reloads today in the 1-7 upper. 55 gr Hornady FMJ with 25.0 gr of H335, WSR primers. 5 shot group at 100 yds. that can be covered by a nickle. That's more like it.

Edited April 9, 2007 by Joe D

[uscbigdawg]

Hi Joe,

Glad to hear it. Sounds like it was just crappy bullets gettin' spun "too hard".

Rich

[Dan Sierpina]

I tried some of my reloads today in the 1-7 upper. 55 gr Hornady FMJ with 25.0 gr of H335, WSR primers. 5 shot group at 100 yds. than can be covered by a nickle. That's more like it.

H335 is THE powder for bullets up to 55 grains in .223

[Joe D]

What is a good powder for heavier bullets - 748 or 2230 perhaps. Would one of these powders work for both 55 gr and heavier?

[No.343]

Joe, I had the same problem in my 1:7 with some Monarch loads. Not only were they not grouping, but some were key holing. Everything else has been fine. I use Varget for 75gr Hornadys, 77gr SMK and 80gr SMK.

[uscbigdawg]

Like others that load heavy bullets (69gr. SMK's for everything) Varget is nice. H335 and W748 (which I think are identical) do okay in the heavy bullets, but Varget is just so much better. And despite what some say, it meters awesome in Dillon powder measures.

Rich

[AlamoShooter]

my Rock river 1-8 did the same thing with most 55s it shoots great at 200+ yards and even better with 75 amax at 500+

the only way I got not bag groups with the 55s is to -Slow- the bullet down into the 2200 fps range = Try the slowest /lightes charge you can load and that should help

I seam to be the only one this worked on though = so I probly don;t know nothing

The test that I did was for bench rest Pdogs shooting I wanted a load that would fit in the mag and a long range over 600 load for the AR don;t ask why

What I found was the group would go to heck at a speed of ..2250 -2300 over that and the goup got big.

And shooting under 250 yards with the 69 & over bullets was silly cuzz the group was bigger at 100 than it was at 250 = the bullet had not stabalized yet thats my story and Im sticking to it

[gotm4]

I've used both 1x9 and 1x7 twist barrels in a few differnent ARs. Usually (as in not ALWAYS) the 1x9 is more accurate with lighter bullets. I still prefer to use 1x7 when available because I can shoot 50-77gr and know even the 77gr long Sierra MatchKings will stabilize. I find the typical difference in accuracy is about .25"MOA, YMMV.

[Shawn Knight]

I have 2 1-7 twist barrels from White Oak Armament and one Match rifle upper from White Oak Precision and they all work well with various bullets weights from 40gr up to 75-77gr. I have not tried any 80gr as I am too lazy to load that long a$$ bullet.