I have been thinking about having a barrel chambered for the 338/408 for my HG if the 350g bullets work in the 338 Nawakwa I will be getting a 40" barrel and new bolt for my 10" Bat and have Bruce Bear chamber it for the 338/408 and see what it will do here is a pic
Crow Mag - You've got me rethinking my idea of a 32 inch Lilja target SS 1.250 6 inches then taper to .875 or so using Lapua 338. My thoughts also included a 2 inch brake bringing the barrel length to 34 inches.
Correct me if I'm wrong. We did some extensive testing in .277, .284, & .30 using the heavier bullets in each class. Comparing identicle loads using slightly hotter powders like 4831,r-22, 7828, MRP in 24 inch barrels vs. 28 inch.
Then and slower powders like 7828, h1000, r-25 h-870 in 26 inch vs 30. We were looking at chrono readings and the gains of FPS with optimized powders for barrel length. Of course it proved that a longer barrels can take advantage of slower powders and have increased FPS.
What I did find is that the speed between 28 and 30 inch followed the law of diminishing returns. That's why i kind of limited my barrel idea to 32 inches.
Your planing on 40 inches. Am I wrong in thinking that the speed increase is minimal over a 34 including a 2 inch brake?
We want the most velocity we can get and still be very accurate. I am talking about a bench rifle around 70 to 90 pounds with at least a 1.450 to 2" barrel no taper in a barrel block. Not something you would want to carry far. I am hoping to get the 350g ULD bullets to a velocity around 3200 fps with a bc of around .920 shot at an elevation of 10,000" above sea level this would shoot very flat at ultra long range and have a substantial amount of energy. I have a 338 Lapua IMP that is in a LG #17 with a 1.250 HV taper 10T 29 1/2" barrel + brake this rifle works excellent for a rifle that is easy to carry and shoot off a bipod.
Dan Lilja did a test on the 338/378 here is a link. http://www.riflebarrels.com/articles/bullets_ballastics/long_barrel_velocity.htm