Barrel twist rates

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15 years 11 months ago #779 by Policeman
Barrel twist rates was created by Policeman
Okay gentlemen,

School me on twist rates/bullet weights for the 7.62 please.

Be gentle :blink: as I am coming up from the 5.56 platforms.

Thanks,

Po-Po

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15 years 11 months ago #780 by weshowe
Replied by weshowe on topic Re:Barrel twist rates
Po-Po,

Barrel twists for the .308 are generally as follows:
Palma shooters: 1:13 or 1:13.5" for 155 grain bullets
Match 168Gr. : 1:12"
Match/M118LR 175 Gr.: 1:11.25"
Match 190's: 1:10"
These are general guidelines and not absolute as bullet velocity and shape come into play. My bolt guns all have 1:10" as I set them up to shoot the heaviest bullet used...in this case 190's. My AR-10 has a Schneider 1:12" that stabilizes well up to 175 grain bullets.

Up this helps.

Wes

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15 years 11 months ago #782 by Policeman
Replied by Policeman on topic Re:Barrel twist rates
So a 1 in 10.5 would stabilize with both (maybe) 175 & heavier bullets?

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15 years 11 months ago #783 by weshowe
Replied by weshowe on topic Re:Barrel twist rates
Po-Po,

The 1:10.5" twist is not standard. Go with the standard 1:10" it will stabilize everything below 190 grains. With lighter bullets the worst case is you are "overstabilizing" them. Ideally, some shooters try to match a "perfect" twist for the bullet used. IE, a 1:11.25" twist for 175 Gr. Sierra Match Kings.
Personally, I can't tell the difference between my 1:10" twist and my 1:11.25" or 1:12" twist guns accuracy wise.
Are you planning on buying a complete rifle and then modifiying it or starting from a bare reciever and upper?
Plan on spending about $600.00 for a premium tube and proper installation...lots of choices. Let me know and I'll help where I can. Barrels are something I DO know about.

Have a Merry Christmas,

Wes

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15 years 11 months ago #785 by Policeman
Replied by Policeman on topic Re:Barrel twist rates
Wes,

I have a 5R barrell that is going to be made in January/February. What I am looking for is something to shoot as precisely as possible out to 800 m with an occaisional 1000m shot.

So from what your telling me I should actually get something like a 1:12 if I wanted to shoot Palma with an occaisional 175 shoot to 800 or more. Correct?

This is going to be a 80% blank. In other words a contoured rifled blank that needs to be cut to length, chambered, and port drilled by a Gunsmith. I AM planning on get the blank and after I finish getting all the components together getting the guys over at GAP to finish the barrel, headspace and mate the upper/barrel. I originally thought 18" final length but have since decided on 21".

Allen

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15 years 11 months ago #787 by weshowe
Replied by weshowe on topic Re:Barrel twist rates
Allen,

Perhaps I wasn't clear...A 1:10" twist should let you shoot any bullet weight from 190 grains down to 147 grains accurately.
The 1:11.25" twist will stabilize 175 grain bullets on down to 147 grains.
The 1:13" twists are used by palma shooters because they are pushing 155 grain SMK's, etc. at some astonishing velocities. In many cases they are using special chambers and seating the bullet out so far only part of the neck is holding the bullet.
If you plan on shooting 175's on down the 1:11.25" twist should be ideal for your purposes and the 175's should stay supersonic to 1,000 yards in most bolt action rifles. The 21" barrel you specify may not generate enough velocity to stay supersonic to 1,000 yards.
Your choice of a 5R barrel is a good one. Who is the maker? Mike Rock? You may want to consider some other makers, too. I'm a big fan of John Krieger's barrels. Not 5R, but excellent tubes. Also, Krieger's can fit and chamber your barrel for you and do a dandy job.
Lot's of choices...which is what makes this so much fun.

Wes

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15 years 11 months ago #788 by Policeman
Replied by Policeman on topic Re:Barrel twist rates
Wes,

Cool, Thanks for clearing that up. I was getting worried I had made the wrong choice on twist.

Yes, Mike Rock is having a group buy @ www.snipershide.com/forum/ubbthreads.php...er=865815#Post865815 and I got in on that. Its still open btw if anyone wants to get in on it too.

I am not counting anyone (barrel makers) out but am really a proponent of the 5R/(argubally)polygonal rifling. I think they add to accuracy, ease of clean up, and velocity. So that is why I have decided on Mike.

Thanks for the info, assistance and patience for a newb. Like I said the information on AR15's are very clear to me. Its this new beast that I am trying to wrap my mind around to learn too.

Merry Christmas.

Allen

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14 years 5 months ago - 14 years 5 months ago #4525 by lotoofla
Replied by lotoofla on topic Re:Barrel twist rates
Twist, also involves shooting circumstances. If your shooting at 10,000 feet at -30 degrees, and zero humidity a 1x12" will work with any bullet. But, if you shooting at below sea level (Palm Desert CA) at 110 degrees with 100% humidity. you need a 1x9" twist to stabilize due to the greater atmospheric resistance. Your safe with a faster twist than a slow one (1x10"). Typically with the 30-06,308 Win a twist between 1x10-12 is OK. Not the problematic situation that you have with the AR-15 223 Rem 1x7-14"(!!??)
Last edit: 14 years 5 months ago by lotoofla.

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