I've had great success with Varget with 130-168 gr bullets. It is my go to powder. I've also used 3031, 4064, 4895, TAC, and RL15. They have all shot almost identical for me. I choose Varget simply because it is the least temperature sensitive. If it isn't working for you there are plenty of other options. I've found 308 to be the easiest chambering to load for. Every powder and bullet I've tried so far has given very good results.
The loads I've chronographed average about 10-15 fps difference for each inch shorter barrel length compared to published numbers in loading manuals. There is far more difference than that between barrels of equal length. I wouldn't give the 20" barrel a 2nd thought, it could well be faster than another gun with a 22-24" barrel.
The loads I've chronographed average about 10-15 fps difference for each inch shorter barrel length compared to published numbers in loading manuals. There is far more difference than that between barrels of equal length. I wouldn't give the 20" barrel a 2nd thought, it could well be faster than another gun with a 22-24" barrel.