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-   -   1x7 twist rate (http://www.firearmstalk.com/forums/f20/1x7-twist-rate-96239/)

Crazycastor 08-30-2013 05:23 AM

1x7 twist rate
 
I have a 1 in7 twist rate on my 14 1/2 inch barrel. What weight bullets shoot best with this twist. Just started reloading for .223 and and recently got an ar15

SSGSF 08-30-2013 05:55 AM

The .223 Rem shoots a wide range of bullets very effectively, from 35gr flat-based varmint bullets, to ultra-long 90gr VLDs. However, you'll need the right twist rate for your choice of bullet. For max velocity and accuracy with the lightest bullets, a 1:14" twist may be ideal. More versatile is a 1:12" twist that will allow you to shoot the popular 60-64 grain match bullets. (However, a 1:9" twist is needed for the steel-core 62gr bullet used in the M855 military loads, because that bullet is as long as most 70-grainers.) For normal lead-core jacketed bullets, a 1:9" twist will let you shoot up to 73gr bullets. Since most .223 Rem shooters prefer bullets in the 50-73gr range, a good "do-it-all" solution is a 9-twist, unless you're a Highpower competitor.

For long-range match purposes, long, high-BC bullets are favored for their ability to buck the wind. You'll want at least a 1:8" twist to shoot the 77gr and 80gr MatchKings and 80gr Bergers. To shoot the new 90gr pills, a 1:6.5" is recommended, though a true 1:7" will work in most conditions.

Overall, what twist rate is best? For varminting we like a 12-twist. The slower twist will give you a bit more velocity, and minimize the risk of jacket failure at high rpms. For general use, an 8-twist barrel will let you shoot the excellent 77gr and 80gr Sierra MatchKings and nearly all varieties of non-tracer milsurp ammo. We'd only select a 1:7" or faster twist barrel if we had a need to shoot the 90gr VLDs.

Triumphman 08-30-2013 06:07 AM

They say from 55gr to the heavier 77gr works better in this twist, but each Rifle, even with the same Twist, will shoot differently. The biggest result for accuracy, will come from the Powder used, and it's measurement, for your reloads. Primers also play a small part, as to how well they strike. It is/can be a slow procedure with trial shots to determine the best loads for which grain of Bullet that you like. Get yourself a Notebook and be prepared to do a lot of jotting down of test procedures of how you load and how they shoot.
There's lots of Loads on the Net, to help you, and they will get you very close, but you still need to do your own testing procedures as to how your Rifle shoots with that Load.

Do you have a Lead Sled to help with accuracy and Rifle steadiness? If not, you really need something to lock down the Rifle. Optics are a plus, and can help, but not necessary. Shoot different Factory Ammos for initial trials(after Zeroing in), to see how well it groups, then pick that, which groups the best, and enhance your reloads from there. This is the way my Dad did it for years as a Gun Smith back in 60/70's.
Del

Triumphman 08-30-2013 06:20 AM

Hey SSGSF, I have been hearing(no proof myself) as I don't have any, but some Folks have been having problems on the longer Nosed Bullets in the AR's. They're hanging up on/under the Feed Ramps and causing many Jams.
Seeing as our new Friend, is wanting to reload for an AR, there might be lots of problems if not Seating correctly, Magazines not feeding right, and BCG, Buffer issues on top of this, if He doesn't know what could be causing the issurs.
Del

Argyle_Armoring 08-30-2013 01:41 PM

I prefer 1:7 twist for the AR's I build for customers. You can shoot 55gr and larger/heavier through that barrel.

SSGSF 08-30-2013 01:53 PM

Quote:

Originally Posted by Triumphman
Hey SSGSF, I have been hearing(no proof myself) as I don't have any, but some Folks have been having problems on the longer Nosed Bullets in the AR's. They're hanging up on/under the Feed Ramps and causing many Jams.
Seeing as our new Friend, is wanting to reload for an AR, there might be lots of problems if not Seating correctly, Magazines not feeding right, and BCG, Buffer issues on top of this, if He doesn't know what could be causing the issurs.
Del

The only time I had this happen to he is , when I did not seat the bullet properly.

Crazycastor 08-30-2013 01:53 PM

I havent fired a factory round yet in my ar, everything I've shot in it since was new has been reloads that I made. So far I have reloaded about 300 soft point 62 grain bullets and 100 62 grain hollow points and they shot great. My problem is Finding these bulleta are hard. My local LGS has 1000 52 grain hollow points and I don't know how they will shoot in a 1/7 twist. I guess what I'm asking is what weights are the 1/7 twist designed for?

DeltaF 08-30-2013 02:10 PM

The 1 in 7 twist barrel is primarily used in military rifles to stabilize the M856 tracer cartridge, a 63.7 grain bullet, out to 800meters as well as the M855, a 62 grain bullet. It is used in match rifles to stabilize heavy 75-90 grain bullets.

Source: www.ar15.com/ammo

Source: www.armystudyguide.com

Quentin 08-30-2013 07:25 PM

Quote:

Originally Posted by Crazycastor (Post 1351608)
I havent fired a factory round yet in my ar, everything I've shot in it since was new has been reloads that I made. So far I have reloaded about 300 soft point 62 grain bullets and 100 62 grain hollow points and they shot great. My problem is Finding these bulleta are hard. My local LGS has 1000 52 grain hollow points and I don't know how they will shoot in a 1/7 twist. I guess what I'm asking is what weights are the 1/7 twist designed for?

Triumphman answered your question above, generally 55 gr and up. You might get away with 52gr but I wouldn't buy a thousand until you know how your particular rifle handles them.

SSGSF 08-30-2013 07:45 PM

[QUOTE="DeltaF"]The 1 in 7 twist barrel is primarily used in military rifles to stabilize the M856 tracer cartridge, a 63.7 grain bullet, out to 800meters as well as the M855, a 62 grain bullet. It is used in match rifles to stabilize heavy 75-90 grain bullets.




The military shoots more of the M855. Which is the length of a 90gr bullet . Then they do Tracers.
That's why they went the 1/7 twist.


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