The NM garand was successfully used in 1000 yd service rifle competition for years, in fact when the m14 was used for xtc matches, the garand was still used by the Navy and Marines for 1k due to the longer sight radius and barrel, plus in the early days of the m14 before lugs , garands were more accurate.
It’s a decades old myth that longer sight radius enables better accuracy or precision. The distance the front sight is from the rear sight does not change how much the rifle wobbles hand held without artificial support. Doesn’t matter if its 28.5" or about 2.5" less or 50" more. If the sight’s LOS visually aligns 2 MOA off center on the target image, the center of the front sight post will appear the same distance off the target center regardless if it’s 1 yard in front of the rear sight or another range to infinity. Remember the front sight must appear dead center in the rear sight aperture for consistency; off to the edge means bullets will strike opposite where it’s seen on the target; the bore is pointing that way.
The US Navy and US Air Force rifle teams used Garands for all ranges after the first M14NM rifles were built. Army and Marine Corps teams used M14's thereafter. But the USN Match Conditioning Unit in San Diego built the most accurate ones. Moreso with the 7.62 conversions that shot better groups from accuracy cradles than the rebuilt M14NM rifles for a short time, then the Army and Marine Corp shops finally fixed all the bugs in their new rifles. The best of both 7.62 M1's and M14NM’s would shoot commercial match ammo from Federal or Remington into 4 inches at 600 yards. That’s better than what the best 30-06 match bolt action rifles would do with Sierra match bullets in the mid 1960's.
Three 1000 yard loads were popular for the 30-06 M1's correctly rebuilt with good barrels that tested a bit over MOA at 600 yards and about 1.6 MOA at 1000. The 600 yard “B” target had a 2 MOA V ring, 3.3 MOA 5 ring; 1000 yard “C” target had 2 MOA V ring and 3.6 MOA 5 ring....
* M72 30-06 match ammo’s 173-gr FMJBT bullet was pulled then replaced with a Sierra 180 Match King; the FMJBT original. This load shot test groups half the size or better than what M72 arsenal match ammo would; it had only one lot of very good bullets whereas M72 (and later, M118 7.62 match ammo) had bullets from 3 or 4 different bullet making machines. Four levels of bullet quality that limited bolt gun test barrels to shoot them no better than about 2 to 3 MOA at 600 yards in arsenal tests.
* Commerial Western Cartridge Company 180-grain FMJBT match ammo loaded about 1/10th longer for single round loading; boxes were labeled “For Single Round Loading Only” because they usually wouldn’t fit in Garands when clipped up
* Any good new case and primer with a Sierra or WCC 180-gr. match bullet over 48 grains of IMR4064. This one was typically the best of these three loads. This powder had the best track accuracy record in 30-06 M1's with 165 through 180 grain bullets, but charges had to be weighed to at least a 2/10ths grain spread as it didn’t meter to uniformly.
Best long range loads for rebuilt 7.62 Garands follow:
* The US Air Force developed the best; new M118 match case and primer, 44 grains of IMR4320 under a Sierra 190 HPMK bullet. Easily shot under 4 inches at 600, under 10 at 1000 yards. The USN shop also used Lapua D46 185-gr. FMJRB .3092" diameter match bullets that shot a little better in barrels with slightly larger groove diameters of .3082" to .3084". The USN shop built the USAF team rifles and all their Springfield Armory arsenal 7.62 barrels were air gauged for uniformity and those at .3078" or less were set aside for match use.
* New commercial case with 43 grains of IMR4064 under Sierra 180 MK bullets
None of the consistently best scores used resized cases; only new ones. Garand (and M14NM) bolt faces were never squared up so fired cases from them had out of square bolt faces. That caused shots to string 90 degrees from the bolt lug in-battery axis; 7 to 1 o-clock. Case head smacked bolt faces off center and that changed the barrel whip axis to 90 degrees from the 10 to 4 o-clock bolt lug axis. It made only ½ to 2/3 MOA difference at range, but the best marksmen could see it easily.
People still use them for 1000yd service rifle but the m110 is slowly taking over. Loads were in the 180-190 range and were hot. Gas plugs were vented with a drilled hole and brass was not reloaded.
Note that the military team best 5.56 NATO rifles shooting heavy bullets never shot consistently good 1000 yard scores compared to what good M1A and M1 7.62 rifles did. Which is why the US Army AMU got the NRA to allow AR10's be classified as “service rifles” for long range matches starting in 2012 at the Nationals. They no longer had any M14NM’s worth using.
Check over on the m14 forum specifically under Gus Fishers section. He was a USMC armorer at the tail end of the Garand and was trained to build them. You'll find loads and tips. If your looking for a used gun find a Don McCoy built gun , or contact Issiac Mccaskill with Cassat gun works
Other ‘smiths at the USN Match Conditioning Unit built rifles after it closed down. Ray Kerbs for one; he’s in Florida now but no longer rebuilds Garands.
I give Charlie Frazier (USN CPO, Retired) credit for figuring out how to make Garands shoot as accurate (precise) as they do as well as develop some of the best loads for them. He first managed the USN Match Conditioning Unit for years after it was established and his best rifle ‘smiths were also retired USN CPO’s; Don McCoy, Ray Kerbs and John Lovric. John Lovric rebarreled a worn out 7.62 M1 barrel for me over 20 minutes time. Took it to a match the next day, sighted in with two sighter shots standing then went on to win the match.