Blaser does not design the mounts to interchange between barrels without adjustment. Each mount has to be fitted to a particular barrel and scope. What the design does allow is removal of the scope for transport with assured return to zero at one's destination.To those that offered advice on the problems I listed in my previous post, I apologize for the delay responding. Sometimes I get an email that the thread was updated, other times I don't. I figured this thread had gone dormant after I made my issues known. Sorry about that!
With regard to the .223 not firing every time, I'm glad that others have had the same issue. It is only with that barrel and bolt face. The only inconvenience is that I'm tempted to immediately pull it partially open and close it again when I hear the click which would be really bad form if it was just a delayed fire. I remind myself to wait 30 seconds. I have some new Starline brass that I'm going to load up just to make sure it wasn't a problem with the brass of my last batch of reloads.
With regard to the scope mounting, my complaint is not with respect to zero it is regarding the mount itself. When I take it off the .223 it fits too loosely on the .375 and must be tightened using that annoying star-shaped screw on the mount and the ridiculously skinny and weak Blaser screwdriver. I solved this problem by buying a beautiful Z8i (yes, I blame AH for that) for the .375 and now don't change scopes between barrels.
Last, with regard to the first round of .375 feeding improperly, I really think it just needs to be worn in a bit. If the bolt is closed when I push the mag into place it works fine but if the bolt is open the spring inside the magazine seems to fail to adequately push the front of the cartridge up and it sits very flat inside the magwell. When I push forward the bullet nose doesn't slide up and into the chamber, it hits something (I think the back edge of the barrel) and stops. If I put the magazine in with the bolt open I just push down slightly on the back end of the cartridge to realign the way the cartridge lies in the magwell and everything works as it should.
Again, thanks to those that offered advice. I won't be as slow to respond next time.
I am still not sure what is happening with the feeding issue. None of mine in any caliber have exhibited a feeding issue of any kind. However, I never load mine by removing trigger group. I simply press the rounds down from the top into the open magazine.