I have some personal experience that may help. I shoot with a buddy of mine quite often with factory loads: FGMM 168, 175, Black Hills Match 168, 175, Hornady Match 168 and ASYM Precision 168. He shoots a Rem factory 5R and I'm shooting a Stiller Action, Bartlein 5R rem varmint counter bedded in HS precision.
Honestly they both shoot the same. He is a tad better one day and me the next. It so close it's basically indistinguishable. I have every intention to start hand loading for improved accuracy just for a entertainment in the off season.
I'm really curious to see what improvements come from handloading. Both guns run around 1/2 MOA even at moderate distance (100, 300 & 400 yards).
Kinda sucks because I built the custom about the time I suggested he buy the 5R (he didn't like the idea of spending the $$$ for a custom) and as of now I can't justify then added cost with performance. I love the rifle and everything about it, but with factory ammo is basically just a 5R.
This is my experience and I'm not saying it's gospel or the case for all in any way; just a personal experience you can draw what you will.
I however am curious what others think about the gains or potential of my rig vs. a factory 5R with proper handloads. Does anyone have any measured improvements from factory ammo to hand loads? I would like to hear those data results. Thanks!