Right on, Steve
It's interesting when we Garand fans try to search out the best loads-bullets, etc some of us get concerned if we're not shooting 1 moa or better, on a consistent basis. As Roy Baumgardner, an authentic expert on the Garand has written over the years, there are a 'few' 1 moa Garands with GI barrels, but not many. And even the 1.5 moa Garands with GI barrels will rarely hold that accuracy for 20 rds.
To get that x ring on 7 of 10 shots means an expensive built match Garand with heavy barrel.
I decided to dig out my armorer/ Ordnance Corps manuals from my days in servioe, some spent as an armorer working on Garands. My National Match & Ammunition manual of 1960 (many if not all of the same rules apply in the Garand matches regarding qualifying rifles) has this to say.
Under acceptance requirements, the standard M1 rifle is fired 5 consecutive shots at 100 yards and the 5 shots must group within a 5.6 inch circle. That's with issue ammunition.
A National Match Garand was tested in a machine rest (fixture) and three ten-shot groups fired at 100 yds using match quality ammunition. The average extreme spread of the three groups can not exceed 3.5 inches. Any one ten-shot group can not exceed 5.0 inches extreme spread.
Steve, your rifle seems to be shooting as well as what was expected of a match rifle shooting from a fixture , based on Army acceptance standards. And far better than the standard issue M1 standards.
The military used mean radius as the system to evaluate ammunition and the 1960 match ammunition requirement was that it must average less than 3.5" M.R. at 600 yards.
A little background on ammo: the ammo referred to as M/1 catridge Cal .30 ball was the match ammo used up until 1941. A 172 gr bullet loaded with IMR 1185.
Around 1940, the original Cal.30 ball model of 1906 was put back into production using a gilding metal jacket and was identified as Cal .30 Ball M/2.
The main combat ammunition in the Garand was 168gr armor piercing 2800 fps and the main training round was the M2 ball with 150 gr bullet at 2800 fps.
All this comes out of the NM manual of 1960 which includes all the details needed to build a match rifle, which our school was required to do before we received our artificer certificates.
So Steve, your rifle (and shooting) is right in there!