Re: .308 barrel twist rate
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: robertsma</div><div class="ubbcode-body">I am looking at either a bartlein, krieger, or rock creek at the moment and I have heard many different things on twist rate. I plan on shooting 168gr HPBT's that I either handload or use FGMM to shoot. .308 cal. What is the best twist rate, from what I have seen on here 11.25 is very common but I have a USMC gunner saying that our sniper rifles are 1-10. Just curious as to which atcually shoots better. Thanks </div></div>
Good variety on any of your barrel choices. I'm a little biased so stick with Bartlein if you can. Plus Bartlein can get you a twist rate that goes into any fraction that you want that goes out to 4 digits.
If you have the option for 168's or 175's smk try to go with the 175's. 175's fly better out to 1K than the 168's do. You'll be hard pressed to get a 175 smk with Varget not shoot well out of your 308. Try that combo and start with .018 off the lands. Many 308 shooters in our club report back that .018 is a good starting point. Also try Berger 185 BT not the VLD...but the BT. They have a very high BC.
With regards to twist rate, there is a standard, like 1-10 twist, that will accommodate many different bullets, but it depends on how anal you want to be. If you want to split hairs like I do, pick a bullet that you have your heart set on and get Bryan Litz's book on Applied Balistics that will tell you what is the optimum twist rate for the specific bullet you want to shoot (or ask someone here on the forum that has his book). You will have the best chance at getting it to shoot the way you want. Not saying that a 1-10 twist barrel will shoot better than a 11.25 twist or vice versa...just the opportunity to have the "optimum" spin on the bullet, based on weight, bearing surface, etc. will be based on accurate mathematical calculations and not someone's opinion.
If you are going to try a variety of bullets, go with the fastest twist based on the selection of your bullets that you intend on trying out.
Lastly, if you are dead set at using 168's, ask your gunsmith about 308 reamer selections. Every bullet/cartridge selection has an optimum freebore length based on where the bullet is seated in the powder column for optimum accuracy. If he can't tell you what it is, call Dave Kiff at Pacific Tool and Gauge and ask him. He'll be happy to let you know what it is.
If your gunsmith doesn't have that reamer, or something very close to it, you may want to purchase it and send it to your gunsmith along with your barrel. Be sure to also mention, should you talk with Dave, what kind of magazine box (BDL, AICS mag, single shot, etc.) and bullet selection you intend on using. This makes a huge difference! You don't want the freebore too long (optimum for specific bullets) and the bullet not fit in your mag box and/or end up having .100 jump to the lands.
Sorry for the long winded opinion.
