Initial Velocity Test. Rifle: Accuracy International. Barrel: Proof Stainless Steel. Twist: 1:9.4 Length: 26 inches. Chamber Notes: Berger 300 OTM will touch the lands at 3.810 OAL. It's jumping around 20 to 30 thousandths when loaded to magazine length. Cartridge Data: 338 Lapua Magnum Brass: Peterson Powder: Reloader 33 Bullet: Berger 300 OTM Overall Length: 2.980 base to tip Primer: CCI #250 LRM Atmospherics Temperature: 68 F Station Pressure: 29.30 hg Density Alt: 1300 ft Humidity: 32% Other Notes: This is with brand new Peterson brass. Brass is ran partially into an RCBS FL Sizing die to make sure the necks are round. Powder is weighed out on a laboratory grade scale to less than .1 grains. The barrel is also brand new with 0 rounds fired. I also had issues with the chronograph not picking up some shots, so that is going to be annotated in the notes. 94.0 gr Velocity: 2590 fps SD: 10.9 fps (5 rounds) 95.0 gr Velocity: 2612 fps SD: 13 fps 96.0 gr Velocity: 2658 fps/ 2695 fps * SD: 18.8 fps / 6 fps ES: 34 fps / 14 fps 97.0 gr Velocity: 2687 fps SD: (Was only able to get 2 rounds to chronograph.) 98.0 gr Velocity: 2758 fps SD: 13.6 fps ES: 34 fps * The second number are the last 5 shots of the day. I wanted to see if the barrel was speeding up as it was broken in, and there was a very noticeable improvement in precision towards the end. That might be because the shooter just decided to shoot better, or the barrel/throat is setting in. Range Note: A lot of these numbers are not going to be perfectly reliable due to the mounting bracket of the Magnetospeed coming loose. We didn't find the proper allen wrench until the end of the day. When we revisited the 96.0 gr load, it showed a lot more consistent numbers. Final Notes: None of the rounds show any signs of being over-pressure. Further research last night lead me to believe that up to 102 grains of Reloader 33 is "safe" (well the gun and brass won't explode...but it might be over-pressure.) The next step is to work up even higher. I am hoping that we can achieve good results around that 99 gr - 101 gr mark with a velocity of around 2850 fps. Based on the feeling of seating the bullets, I believe the consistency of the ammo will be improved by the use of an inside neck mandrel from Sinclair to have more consistent neck tension. The seating depth will also be reduced by 5 to 10 thousandths because some rounds were getting caught up in the magazine.