used b-sqaure one piece and two piece and sportsmatch atp61's.
atp 61's are my fave by a long way, but i'd prefer any over shimming....
b-square 2 piece are ok to setup but fiddly and they don't come centred, if you ignore the need for 4 imperial allen keys... but you can change the elevation my lifting and rotating the dovetail mount on one of them with ease... the 1 piece are a ***** requiring the scope is unclamped first.
none of them have shifted on pcp or springer.
the b-squares are also mega tight on tolerance, meaning all bolts have to be perfectly square to work, even the rail clamp on the one piece needs to be parallel to bind up right, else it snags...
my only gripes with the sportmatch is that the allen bolts go rusty very quickly, that you need 4 metric allen keys... but they are simple to setup and use, about 2 secs longer than a standard set and better than shimming.
somewhere along the lines, b-square changed the post thread pitch, which is a nause because longer posts may not fit newer/older mounts...
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