While I have my 375 BigBore apart, recrowning, etc... I was thinking I should try shooting for groups with the magazine and forend removed... theoretically, this should give me the best possible chance for grouping, correct? No forend or barrel band to interrupt harmonics... as long as I don't rest any part of the barrel on bags, this should be the best the gun can shoot.... or am I missing something?
I figured if it shoots really well like that, I can use it as a benchmark to tell when I have it back together correctly... any thoughts?

I don't know why you'd need (or want) to go to so much trouble. Do you expect to hunt with the rifle in that configuration? or maybe shoot bench-rest competition with it? My Wild West Guns Alaskan Guide in .45-70 will consistently shoot .75" and smaller groups with factory ammo and just a little better with handloads. I only take it apart to clean it once in a while.

It's really not much trouble.... MUCH less trouble than Wild West probably went to, to get your rifle to shoot those groups..... Mine didn't group as well as I thought it should... I got it at LEAST second-hand... the muzzle had some wear and a ding in the crown that didn't appear to affect the bore, but I wanted to improve it... so I chucked it in the lathe and recrowned it. Now, before I put it all back together, I thought I'd shoot it with no outside "influences" on the barrel (forend and mag tube/barrel band). That way, when I put it all back together, if it groups worse than when it was "stripped", I'll know that either the forend or the barrel band, or the mag tube is affecting accuracy.....
I was just sorta wondering if anyone else had tried that, or if I was just spinning my wheels.... I mean, we're only talking one extra trip to the range... in fact, I can probably take the parts/pieces with me, and shoot it stripped, then assemble it, and shoot it dressed for comparison...... sounds like a plan.