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Madball6
April 7, 2011, 01:13 AM
Im a new AR15 owner (my first) wondering about the ballistic differences between these two riflings. What are the differences? What grain bullets tend to shoot better out of which barrel? I'll admit, i bought mine without researching the difference (which is rare for me usually i research to death) was wondering what people that had experience with one or the other, or both, thought. Thank you for any input in advance!

-Keith

Sport45
April 7, 2011, 01:57 AM
Which one did you buy?

They should both do pretty good with 55gr and heavier bullets. My 1:7 barrel likes 62-68gr a little better than the 55gr pills. It really likes 75-80gr bullets.

If you want to load cartridges that are short enough to fit in the magazine the 1:9 should be fine.

Madball6
April 7, 2011, 02:08 AM
I got the 1:9 but now im afraid i wont get the accuracy i want out of bullets that are more then 50gr feeling buyers remorse that maybe the 1:7 should have been the way to go.

Jim243
April 7, 2011, 03:15 AM
Keith

You didn't say if you reloaded or not, just that you purchased a new AR.

First I have three 223 rifles, two ARs and a bolt action. All three have a 1:9 twist and all will work well with up to 80 grain bullets without a problem. As so should yours and they are all within one half MOA of accuracy.

The problem will come in not in the twist rate but the length of the bullet. The max OAL for a AR is 2.260 inch because of the magazine. Any round longer than that and you have a single shot AR. Most of the heavier weight 223 bullets, say anything beyound a 69 grain will require a length that will have to be feed in one at a time. And depending if your AR is 5.56 or a true 223 the chamber will limit you as to how heavy a bullet you can use.

So the short answer is your twist rate of 1:9 will do just great with any round that is made for an AR. You will only get into accuracy issues with the 75 to 80 grain bullets which will work much better in a bolt action rifle.

Jim

Technosavant
April 7, 2011, 10:41 AM
I got the 1:9 but now im afraid i wont get the accuracy i want out of bullets that are more then 50gr feeling buyers remorse that maybe the 1:7 should have been the way to go.

1 in 9 will be fine with 55 and 62gr bullets. You might have issues stabilizing the super heavy bullets like the 75gr rounds, I've heard of some where it works great, but generally 1 in 7 is better for those heavy loads.

Generally, the least expensive ammo is 55 or 62gr, so unless you go for the expensive premium stuff like Hornady TAP, you won't have any problems.


The general rule of thumb:
1 in 12 twist: up to 55gr
1 in 9 twist: up to 62gr
1 in 7 twist: pretty much anything, but may overstabilize 55gr.

kraigwy
April 7, 2011, 10:59 AM
If you have a choice, go to the faster twist. The 1:7s will shoot anything the 1:9 shoot, the reverse isnt true.

Check out this example:

http://photos.imageevent.com/kraigwy/pentest/websize/Twist%20compairson.jpg

Bartholomew Roberts
April 7, 2011, 11:03 AM
Most of the heavier weight 223 bullets, say anything beyound a 69 grain will require a length that will have to be feed in one at a time.

ARs will feed up to 77gr Sierras and 77gr Barnes TSX from the magazine without having to be single fed. I can vouch for those two on personal experience.

kraigwy
April 7, 2011, 11:15 AM
BR is correct, the 77s are designed to be loaded from the magazine. That's what the army used in their Squad Designated Marksmanship Rifles.

The 80+ grain bullets need to be seated long, but they are for long range matches which require single loading anyway.

jglsprings
April 7, 2011, 11:23 AM
I have had good luck with the 75 gr Hornady A-MaX in a 1:9 barrel.

Quentin2
April 7, 2011, 12:16 PM
To be fair the targets Kraig showed compare 1:12" vs. 1:7" twist. Of course his conclusion of going with 1:7 is correct, especially when heavier, longer ammo is used.

It would be interesting if the field manual had also included 1:9" just for shins and grits.

kraigwy
April 7, 2011, 12:37 PM
The 1:9 will work on bullets <69 grn. but normally it wont work with >77 grn bullets. There are exceptions but the 1:7 will shoot the lighter bullets. Most of my HP practice is at 100 yards on reduced targets using 53 grn hornady's. They are excellent out of my 1:7 White Oak Service Rifle.

My opinion, for what is worth is to go for the faster twist, you wont be limited to lighter bullets, you can go from 50 - 90 grns, ( I haven't tried 40 grns in a 223).

HiBC
April 7, 2011, 02:53 PM
OP,you say you already bought the 1 in 9.Don't worry,be happy!
I can agree with what others have said if you are going to shoot competition,but if its a general purpose shooting rifle,1 in 9 is just fine.The 69 gr Sierras and Nosler comps will shoot great,and actually you do not lose all that much BC,and you gain velocity.look at Varget and RE-15 for powders to try.Typical accuracy is excellent.
When you look at varmint bullets,bullets that make more humane kills,there isn't much past 62 gr.
If you want to feed from a magazine,all you have lost is the 77 gr bullets.For the most part,that only matters if you are shooting in competition at 600 yds,in my opinion.

Buzzcook
April 7, 2011, 03:02 PM
What is the intended use of the rifle? Unless your doing serious long range shooting you should be fine with 62gr and smaller bullets. If you're varmint hunting a 50gr Barnes will do for coyotes. For plinking and just having fun the cheapest bullets you can find are what you want.

FALshootist
April 7, 2011, 05:45 PM
1 in 12 works great for up to 55 gr bullets.
Most 1 in 9 work great with up to 69 gr bullets
anything heavier will usually need a 1 in 7 twist.

People make a lot more out of the 1 in 7 twist than they have to. The 1 in 7 twist rate really came about with the military trying to make more out of the 5.56 that it really was.

As others have said the most common and cheapest are 55 and 62 gr bullets. They work great in 1 in 9 and many 1 in 12s will also handle the 62 gr. But the 1 in 12 really shines in the 55 and lighter varmint bullets.

There are better calibers for the over 69 gr bullets (they just don'tfit in the AR 16/M16 magazine).

Madball6
April 7, 2011, 07:08 PM
What is the intended use of the rifle? Unless your doing serious long range shooting you should be fine with 62gr and smaller bullets. If you're varmint hunting a 50gr Barnes will do for coyotes. For plinking and just having fun the cheapest bullets you can find are what you want.

Mostly plinking, but was hoping to use it on smaller game as well, up to wild hogs. As far as range goes, I dont intend on shooting at any over 200yds, and the vast majority would be 100 yds and under. Getting a scope for it soon, I guess i'll test some different loads and see what happens. For the record the rifle is a SR-556. Like it so far, shoots well at 50 yards with the troy battle sights. Won't have a full eval on it til i get a scope on it and get it zero'd.

Jim243
April 7, 2011, 09:04 PM
ARs will feed up to 77gr Sierras and 77gr Barnes TSX from the magazine without having to be single fed. I can vouch for those two on personal experience.

Bartholomew,

Are you using a 223 chanber or a 5.56 chamber with those bullets and the differences in accuracy? What has your experience been.

Jim

Bamashooter
April 7, 2011, 09:33 PM
My mini shoots 60gr. 65gr. 69gr. just fine. I have shot a box of 75gr. without any issues, but generally just stick with my 60,65,69gr reloads.Is a 1:9 twist.

mc223
April 7, 2011, 09:46 PM
A lot of general bad info in this thread. To the OP, You will never know what your rifle will do until you try it.

Some 1in 9 will shoot everything from 50g to 80g and some not.

Can the remorse and leave the forums alone. Go Shoot, then come back and tell us how much fun you had and what your experiences were at the range.

Buzzcook
April 7, 2011, 10:47 PM
If hogs are the biggest game your going to shoot, you should be good with a 60gr sp. That is unless you run into hogzilla:D

Blackops_2
April 7, 2011, 11:17 PM
1:8 another twist noone added will stabilize anything from 55-80gr from what i've read. Bout to order some Black hills 77smks.

Bartholomew Roberts
April 8, 2011, 08:37 AM
Are you using a 223 chanber or a 5.56 chamber with those bullets and the differences in accuracy?

I am using a 5.56m NATO chamber and a hybrid-chamber (similar to Wylde; but that particular barrel maker's version). As far as sitting down and making a good honest effort for precision vs. close enough for 3-gun, I've only done that with the 77gr Sierras (Black Hills blue box, red box, and the older white box Mk262 stuff that used to be available to civilians). Accuracy was around 1" (5rd groups at 100yds from bench or prone through a 16" Lilja match barrel) for all of those different 77grs (probably more of a shooter limitation than an ammo limitation). Although the Mk262 stuff did tend to open up a little more than the lighter loaded .223 pressure 77gr.

Out of a 5.56mm NATO 1:9 Bushmaster 16" barrel, the 77grs did about 4-5" for me at 100yds, which was disappointing; but that same barrel wasn't great with 68gr or 69gr either. Accuracy wise, haven't shot them for precision out of my 5.56mm NATO CMMG 1:7 barrel as it has A2 sights and usually I use the Lilja when I am trying to get an idea of how precise I can shoot.

No problems feeding any of those via magazine in my rifles, though I've seen other people have trouble with 77gr ammo in their rifles when 55gr or 62gr was feeding fine for them. My guess is that their cyclic rate was too high or that their magazine springs were on their last leg.

BIG P
April 9, 2011, 12:17 AM
My 1:9 works good from 50GR - 69gr know problems.