I just went to load some 270 gr barens 3x for my cz 550 375 h&h. I looked at the recommended COL for the bullet and it's at 3.570. Barnes recommends .050 off of the lands for best accuracy. I went and measure my max COL with this bullet and it measures 3.780 in my CZ rifle. With barnes reccommendations, that put my COL at 3.730. This is a 0.160 difference from the manual. With the manual COL, it seats in the first groove of the bullet. With the recommended COL for accuracy, it seats between the 2nd and 3rd groove on the bullet.
Is this anything to be concerned about?
Does anyone else with a CZ rifle have this deep throat also?
I loaded some of the ammo to 3.570 and some to 3.730 to try. The 3.730 fits in the magazine and feeds fine without any pressure closing the bolt.
Should I just see which one shoots better and stick with that COL.

I expect with the large difference in COL it will give more case capacity and lower velocities and presure slightly.

By all means if your clip lets you hang it out that far give it a go. Many mfg's are now putting lots of freebore into their mag calibers. It's really cool that they gave you that much magazine length to be able to hang out the cartridge. JUst make sure you can eject that long of a case as sometimes that's a problem clearing ejection area with an unfired round. You may see slightly less speed with the bullet hung out but not necessarily. I'd work with a chrono and see what it says. Accuracy can come ANYWHERE with seating depth and could be at the shorter length...the longer length...or anywhere in between.

SPECIAL NOTE ON CARTRIDGE OVERALL LENGTH “COLâ€
It is important to note that the SAAMI “COL†values are for the firearms and ammunition manufacturers industry and must
be seen as a guideline only.
The individual reloader is free to adjust this dimension to suit their particular firearm-component-weapon combination.
This parameter is determined by various dimensions such as 1) magazine length (space), 2) freebore-lead dimensions of
the barrel, 3) ogive or profile of the projectile and 4) position of cannelure or crimp groove.