Winchester 555

I like the Winchester M-22s more, the bullet is rounder and feed 100%. The 555s have a slight truncated shape that will FTF every 20 rounds in my dedicated 22LR AR upper. Both are pretty clean, the powder charge and groups are very identical.

Oh, the AR uppers actually group tighter w/the dreaded Remington GBs than CCIs, go figure. And, they don't have any FTF or FTEs either w/GBs.

I have had horrid results with the Winchester 555 in my Remington 597. But ammo from the same box was grouping great in my grandad's old J.C. Higgins model 30. Go figure.

I've only used the 555 in my GSG 1911-22, and it works great with it...

We've burned threw a couple of boxes of the 333 (same as the 555) figure about 1% FTF's?, my 39A really likes them, my 9422 does well with them also our Marlin 25's also seem to like them, don't recall how the Henry did with them?, haven't put and down the tubes of the Marlin 60's so I can't say how the cycle an auto?, all of them I've shot are in the red box, I've heard the new white boxed ones aren't as good?

Win555 is the backup option if Fed550 isn't available.

I've reliability tested both (and Rem550 Golden Boogers) and they have similar rates of failure (5-6 per box don't fire on first try, 2-3 of those don't fire on three tries, less than "one per box" incidence of a completely mis-shaped round. Those numbers were signifigantly higher for Rem550GB, around triple, if I remember right)
Of course, my testing method doesn't account for all the bad primers that aren't in the portion of the rim crimped by the FP, so who knows how many priming gaps there really are. I also failed to actually count rounds, I was just marking on the box-top flap with a sharpie and realized AFTER two bulk packs of each that I should have figured out if the advertised number were in the box, I doubt it is exact but I'd bet there's extra in any given box, much like the loose 9x19mm 100-round packs from Winchester (generally 101 or 102)