Originally Posted by Long Time Long Ranger
3000 fps is to much to expect from this case with a 300 grain bullet. About ten years ago when the Lapua and ultramag cases first came out I worked with several variations to try and come up with something to beat the 338-378 wildcat I had been working with since the late 70's. I exchanged input from a number of 1000 yard shooters who were also working on different variations of the Lapua. We all found that with a hunting weight rifle 3000 fps with the 300 matchking could not be acheived without risking blowing up your brass or your gun unless you had a one in a thousand super fast barrel that comes along very rarely. The variations of the Lapua shoot best in the 2800 fps range just like the 338-300 ultramag. Some are getting into the 2900's with good accuracy if they have a fast barrel. At this velocity they are extremely accurate and will kill anything at any range that would be acceptable in a hunting situation. If you want to build one it is a great round but don't build it expecting something there is a 99% chance it will not do and blow yourself up trying.
If you want 3000+ fps with a 300 matchking you need to move up to a 338-378 wby custom rifle that will get you there without blowing up your rifle or your brass. I have already been there, done that working with the 338's for over 30 years and if you want to make the next step up above any of these you have to go with something off the chey-tac case and they are just to heavy to hunt with.
This certainly has not been my experience. This year I have built 12 , 338LAIs and all my clients are reporting the virtually the same velocities I have achieved with my own 2 338LAIs. Which is 3050 to 3090 fps shooting 300 gr SMKs.
I use Rock Creek barrels for most of my custom builds, they seem to be a "fast" barrel, as the Pacnor I used on another 338LAI did not achieve the 3000 fps mark.
To date out of both my persoanl rifles I have 12 adnd 15 reloading from the brass and no signs of not getting many more.
The barrel length I found worked best is 29 to 30"
The powder that I have had fantasic results with is US869, even at 117 grs did not result in any pressure signs, accuracy went for a dump, most of the rifles I have built in this caliber seem to shhot best using 110.5 to 112 grs of US 869, still getting plus 3000 fps with the 300 gr SMKs and just over 1/4 moa groups.
Barrel life seems to be far better than expected as well.