Originally Posted by bsl135
Unfortunately the exact thresh-hold between nose slump and no nose slump is not well defined. You might get one .338 LM to shoot fine, but due to differences in barrels and their influence on max pressure, another .338 LM may have problems. Even the same LM could have problems with certain powders (like faster burning ball powders) while other powders might keep pressures below the thresh-hold.
It's not possible to tell if you'll have nose slump based purely on MV either. The slump results from exceeding a certain max acceleration, which is directly proportional to max pressure. The MV is related to max pressure, but it doesn't tell the whole story. For example you could have a 26" barrel produce only 2800 fps but have a higher max pressure than a 30" barrel that produces 2850 fps (for example).
The best way to tell if the bullets will work in your rifle is to test them for precision at 100-300 yards. If you find it difficult to shoot under 1 MOA (in a rifle that's capable of less than 1 MOA) then the bullets are probably slumping. For rifles that do not produce slump, the precision is pretty easy to find. In my Edge, I tried seating depths of 0.015", 0.030", 0.045", and 0.060" off the riflings. All 4 seating depths produced about the same groups. I ended up going with the 0.060" off load because it produced the lowest velocity spread. I'm loading 92 grains of H1000.
Bryan, you may have answered this in another thread, but as yet i have not found a response from you to kirby allens issues with this pressure theory...
From some of his testing, he stated that he tried some very light loads of H50BMG in the cheytac size cases to the point where he was getting hang fires etc... he estimiated that the pressures would have been 50,000psi or less, but obviously with long barrels and such a large case, velocity was still quite high.... However, he was still getting the accuracy problems and suggested is was more the velocity and specifically the RPM`s rather than pressure deforming the bullets.
Im simply curious, but how are you determining that it is inface 'nose slump' rather than some other form of deformation, and that it is caused from pressure and not excess RPM`s?