Re: .338 Lapua Mag.
Thank You Dave. Yes, the plain Lapua is a very good chambering. I have a 31" Border barrel 1:10" twist that I have played with for two seasons along with getting the stock ready and heavy enough. The recoil and torque is surprising at these levels of power, so I canīt say that the package is quite there yet for competition, especially the part that pulls the trigger.
The reason I started thinking of an Improved was that I have to fullsize the cases too often for my taste. In my HV BR in 6BR I got about 20 stiff reloads out of the cases with no lengthening of the cases before I had to fullsize them. A 30° angle and pretty straight taper evidently does the trick. So I ordered two body reamers from Elliott with 33° angle and absolutly minimum taper. Iīm no beliver in very steep shoulder angles, yet.
The pilot is 22 caliber, so I have plenty of options and the possibility to shorten the case for smaller calibers. My smith is chambering a 31" 1:8,5 twist 308 right now (he isnīt answering any calls, which is a positive sign). But the 338 is, and will be, my main caliber.
sr90. In a Hodgdon 2000 manual the pressures of various belted magnums are listed at 53000 to 54800 and the 300RUM at max 63100 CUP. CUPīs are, ofcourse, not direktly comparable to "real" measures of pressure. These should roughly correspond to 430/440 and 460MPa. Canīt find the translation factor for PSI to MPa. One pound is .4536kg, and sq inch is .00064516m2. That would make 1Pa=703.7 PSI. But one Pa is 1Newton/m2 which includes an acceleration of 1m/s2 that I can recall how to handle.
In a brief moment of obstinacy I exceeded the reloading data with N170 and got the Scenars to 3120fps, but the cases popped out of the chamber as with midrange loads. I got the feeling that the rifle breaks before the case. They are apparently almost idiotproof, the rifles _might_ not be, especially if buildt on narrow threaded actions. AKI