We fit Atlasworx mag systems almost daily however 300wm T3 AI type less than 10%. The T3 is a bit tight for the AI 300WM mag, some say mill 2mm off the trigger housing but we found that is not needed. Recently a picture was posted on this thread where the front bottom of the action had a V cut-out which could make good sense for longer loaded cartridges. I have not tried that yet.
I think it is important to first bed the action which means the position is fixed, then free float bed the floor plate in it's natural position with inserted magazine which sits in the best position and angle in the action. We start by having the mag inlet larger than needed.
One can simulate the best position by clicking the magazine in the atlasworx then sitting the mag in the action, (without the stock) fit the action screws very lightly tightened. Pillar height can be measured that way also.
Once fitted and bedded right the rifle feeds ultra reliably. pictured a 7RM with Hardy barrel, Atlasworx AI 300wm mag.
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