Re: .338 Lapua ackley
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.
Predictions are difficult, especially when they involve the future