We can't help but speculate and debate this to death because Alliant didn't publish sufficient information. I suspect(but don't know) that the .41 mag issue is that they don't trust their own data with new lots. Despite decades of 125 grain .357 and Blue Dot use I suspect that there may have always been a problem tied to burn rate and cylinder gap/forcing cone jump. Most of us are aware that the factory .357 has been gelded and S&W introduced the L frame due to premature wear of police K frames firing 125 grain .357s. it seems that hot 125 grain loads arethe biggest offenders when it comes to gas cutting of the top strap. My own hypothesis is that in some guns with rough forcing cones the normal pressure spike which occurs in revolvers during the cylinder/barrel transition can get completely out of hand with Blue dot. I also wonder if perhaps some of the huge cuts in published 4756 data might be due to such spiking.