Good shootin'!
I hear ya regarding losing brass in snow. I've found some of my own brass a couple springs after a bigger snow winter. Not that we've had a ton of snow, but somebody left me over 40 pcs of once fired PPU .30-06 this winter. That's a full set for a CMP match, LOL.
You sure that Criterion barrel is a 4+? Though many USGI barrels can actually gage at ~1 even when new, a Criterion usually starts as a '0'. A 4+ would be a metric shit ton of wear on a Criterion. If indeed that's the measure, scoring in the 90's at 200 yards is very good.
If you have a chance to borrow a proper service rifle sling and can set it up and use it correctly, that should tighten up your group quite a bit, not that a score in the 90's is bad- but you just might bump that into the high 90's.
As mentioned by Mac, there is some fine tuning for Garands that can tighten up the groups as well.
Guess I need to drag out one of my Garands over the next few days. Probably will be the National Match clone I cobbled together a few years ago.