I have owned 5 rifles chambered in 222 Rem (Savage 112JRS, Rem 788, Rem 700 Varmint, S&W 1500/Howa, Sako A1 Varmint), and now just have one (the Sako). All were 1-14" twist barrels.
All were accurate enough. Never went through an exhaustive test for any of them, as they all shot OK(<1.5 moa). I acquired several powders and bullets.
My best accuracy tended to be with 50 grain bullets (never tried 40 grainers). My across-the-board generally most accurate bullet is the Sierra 50 grain blitzking. Other solid performers were 50 gr Hornady ( regular and sx), Sierra 50 gr plain and Blitz, Speer 52 grain HP (flat base).
No one stand out powder, but my Sako shoots AA2015 and 50 grain Sierra blitzkings in 0.5 moa groups to 200 yards (1 moa at 300 yards). I think it was the second load I tried in it, and stopped experimenting with load development once I found that load I've had some rifles respond very well to H4895, imr 4198 , imr 3031. Never had much luck with H322, Reloader 7 or BLC2. Not saying any of these are the best or worst powders, because all were pretty accurate- just my findings from my shooting. My brother has a Winchester model 70a sporter in 222 Rem, and his load is a 50 grain flat base Hornady over 19-20(?) grains of imr 4198, for an honest MOA load to 200 yards.
Set a realistic accuracy goal, such as 1 moa, or whatever you need. Then, once you achieve it, practice with it in the field. Practice range estimation, shooting in the wind, and getting a solid shooting position. It makes little sense to me, as a woodchuck hunter ( where 300 yards is a LONG shot for a 222 Rem but possible if wind is low), to try to find an accuracy group of 0.5+ moa ( theoretical group size of about 2"@300 yards), and then ignore other variables that have more affect of deviating bullet impact in the field (wind, range, shorting position).. A 1.25-1.5 moa capable 222 rem, used by a shooter with real world ability to shoot in the wind to 250-300 yards will do MUCH better than a 0.5 moa load shot by a inexperienced shooter (regarding wind drift, shooting position and range estimation) at those distances. So, set an accuracy level, get a working load, and practice with it. Who knows you may have to shoot from a sitting or kneeling position, or even offhand. Just because your have 0.5 moa grouping potential off a benchrest doesn't mean you will have 0.5 moa in the field ( you won't. more like you will double the group size in the field). Practice shooting at your longest intended range. A load that shoots moa at 100 yards will likely be VERY different at 300 yards, especially in the wind, in the field. If it is windy, GO TO THE RANGE (or field), and practice in those conditions. You will learn a lot.
The biggest problem with most 222 Rem rifles is the 1-14" twist barrel. Bullets with higher ballistic coefficient (which are longer, heavier) can't be stabilized with a 14" twist barrel for longer range wind drift reduction. A boat tail 55 grain .224" bullet is about the longest/highest BC bullet you can shoot in a 14" twist 222 Rem (and that is iffy and depends on the gun and load). I wish 222 Rem rifles came with at least a 12" twist barrel- might be able to shoot flat base 60 grainers reliably. That's where a 223 Rem bolt gun with a 9" twist barrel beats a 14" twist 222 Rem, as it can handle a high BC 60-69 grain bullet for 300+++ yard shots (less wind drift).
One thing I would strongly recommend for improved accuracy, is to get a K&M flash hole uniformer, and prep all your brass. Greatly increases consistent powder burn for improved accuracy on all loads you test.
Have fun being a rifleman ( meaning, being a shooter that knows how to shoot a rifle well in various conditions and positions). Get a working load, then work the load. The 222 Rem is a great cartridge. A "good load" will be accurate enough to make head shots to 225 yards, maybe 250 yards, as a chuck's head is about 3-4" from the side. A 222 Rem load yielding 1 MOA, shot by shooter who can shoot in the wind, will do well to 250+ yards. Further, if you practice in those conditions.
Last edited by buttstock; 01/13/19.