The two bullets I have used to date are a 350 Linotype flat nose bullet and the Woodleigh 410 gr solid that Kynoch loads. Neither deform in the magazine. I have the 350 gr loaded to about 34,000 psi to keep velocity reasonable for a cast bullet (2300 fps), which helps. I do get deformation of the cast bullet when I seat them in the case, as I get a distinct ring around the nose. I assume that is from a seater cup that is too small in diameter. I may open it up to see if that solves the problem.
You might want to place an 1/8" thick plastic shim in the front of the magazine, but if those are spire points, I think there is little you can do to prevent deformation. These rifles do set back pretty hard, but with their excellent sectional densities and ballistic coefficients, accuracy shouldn't be an issue, and penetration should be awesome. I have a downed oak tree from the hurricane, and I shot the tree at a point where it is about 18" in diameter, and the Kynoch solid penetrated the entire tree and continued it's southerly journey. I still need to sit down at the bench and check accuracy, and I may do that today. I am having no problems with offhand recoil, but from a bench I may experience something different.
What bullet/load are you using?
jt