I use a Hornady Lock n Load OAL gauge for my Sako TRG22 and it's really tightened up the group size BUT I found that even more important than that was to ensure the concentricity of the loaded rounds. I bought a Hornady Lock n Load concentricity tool off thebay for half price of a new one and that was a revelation! My TRG will regularly and repeatedly shoot 0.25 moa (with witnesses at Kynamco range) if I take total care at my end of reloading, but that was increased to just under 1 moa using Federal Premium Gold or nearly 2moa using Privi match!!! Something I didn't expect was when I put factory rounds through the concentricity tool I found that the run out on even the most expensive factory (at the time it was £38 for 20) was erratic and accuracy could be tightened up enormously by doing the same thing with that.

Word of warning though - any deviation from standard oal - whether longer or shorter will make a difference to chamber pressure so ALWAYS look carefully at your fired cases for tell-tale signs, make changes very slowly and stop at the first unusual sign.