barrel length

[fatalbert]

I am new to the bench rest world so I need all the help I can get.I am starting a build on a 30BR and have not found much on barrel length in the way of research material. After reading the sight for several days I feel sure there is plenty of info for the asking on this sight.I have a model 70 in 308 that shoots .5 groups with 168gr.HPBT's. It is in a H_S Precision stock and has also been glass beaded.I plan to shoot this gun in club matches and possibly other matches if I can make it shoot.My question is what length barrel should I have put in it, I plan to put a 1in 17 twist in but not sure how long to go. Any other advice is welcome on this build I know from experience two heads are better than one when it comes to guns,so the more the better!

 

[12man]

My 6MM BR has a 22 inch Lilja it is acarry varminter.I am in the process of building another, this one will have a 24 or 26 still deciding. Not sure of the 30 BR

 

[spclark]

Something somewhere I read in the past month or so was a barrel length study run by cutting off an inch at a time & then testing the velocity & accuracy results....

Seems like the optimum is around 28'; certainly you can buy and shoot longer tubes but the benefits aren't as quantifiable unless you want to plan on rechambering / setting back at a later date.

30' is kind of the de facto standard for Palma shooting with .308, 26' for Match Rifles in OTC shooting.

1:17 seems slow for .308 but I don't shoot bench rest. That twist would require fairly light bullets; what's 'normal' for 30BR? For Palma it's 155 in a 1:13 traditionally, though many in the US use anything up to 210 grain,not legal for Palma events internationally) with as fast as 1:10.

 

[GermanS1]

Albert, first you need to determine if there is a weight limit in the class you want to shoot. If there is, that will be the driving force in your selection of barrel contour and length. Go to the place you want to compete at, talk to the match director and get the info. After that, calculating the barrel profile won't be too hard. The 112 gr. to 118 gr. bullets and fast powders that the .30 BR uses won't need a very long barrel to work well. Sounds like a fun project!

 

[LHSmith]

You' re-barreling the M70 to 30 Br? Correct?
What format is your club shoots....score matches?
VFS,3' fore-end), or Varmint Hunter,2 & 1/4 fore-end)
Most IBS competitors use from 112 gr. to 125 gr. bullets with a fast twist ~ 17-18 twist.
My VFS 30 Br has a 23' tube, while my VH 30Br has a 22' tube.
Both were smithed by a BR competitor and reknown gunsmith.
I believe the length has more to do with 'balance'... that is the way the rifle tracks in the bags than any performance aspect.
BTW an excellent production bullet is the 125 gr. Speer TNT HP.
Smokin' Joe Entrekin who follows this site was one of the early pioneers of the 30 Br..and may be able to help you further.

 

[tenring]

With the 17' twist, you will need bullets in the 112 - 125 grain category. The Speer 125 grain would be an excellent starter. I like short barrels to reduce barrel whip and give me good balance. My PPC's and BR's are all around 20 - 22'. After you have set on a particular discipline and know the weight limit for the class you wish to shoot, talk to your gunsmith. He will cut the barrel enough to keep you within the weight limit. Don't forget scope and mounts are included. You will lose around 25 - 40 fps for each inch shorter the barrel is cut.

 

[Hammer]

Don't have a 30 BR.

Have 7 BR and 6 BR barrels made by Pac-Nor.

Both are 30-inches long with 8-inch twists.

Shoot fine.

.

 

[alf]

My VFS gun has a 17 twist Rock cut to 25', but we had 13.5 lbs. to play with.

Al