When the M1a ruled the firing line the bullet choice was uniformly the 168 grain match bullet. If someone wanted low recoil for standing and sitting, any 125 grain bullet would do the trick. The primary reason the 168 ruled was due to the gas system and the selection of match bullets available to the shooter. Few highpower shooters have access to a 300 and 600 yard range, so bullet choices were made by looking at claimed ballistic coefficients and load data. Shooters wanted to use the bullet with the highest ballistic coefficient. While a 190 SMK has a much higher ballistic coefficient than a 168, a 190 is hard on the rifle. (I never tried 190's). The military match bullet, the 174 gr FMJBT was the best ballistic coefficient in its weight class, but the bullet was a FMJ bullet, which are never as consistent as the hollow point bullets. For competition shooters, the 168 gr Sierra Match King bullets were accepted as the standard.
At 100 yards, 17 rounds on target, the old 174 FMJ will hold the ten ring in a 30-06.
I don't remember when Sierra made the 175 Sierra Match King. The shape of this bullet copies the military bullet but the jacket and weight distribution were much better. As I recall, the introduction of the 175 SMK was after the Army won the 1995 National Matches with their M16's, and in just a few years, the M1a faded from the firing lines. I doubt the 175 SMK would have kept the M1a on the line longer, as the rifle simply kicked too much. And the ballistic coefficient of the 175 is not hugely better at 600 yards than the 168. As the Marines told me in 1997, the year the USMC Rifle team went 100% M16, their standing scores were about the same, scores and X counts were a little better in rapid fire, and the 5.56 was a little worse at long range. The improvement in groups at 200 sitting rapid fire and 300 prone rapid fire were the primary reason the 5.56 rifles displaced the M1a. I shot both and I had a lot more time to aim in the rapids with the 5.56 as the gun did not recoil as much and kick me out of position. You could have the shooting position of an invertebrate, and yet still shoot well with the AR15. You had to have a perfect, strong, position to shoot an M1a. It was position, position, position. And sight alignment and trigger pull.
Since a 125 would do all you wanted at 200 yards in the M1a, and the 168 had the better ballistics, 150 grain match bullets were more or less, a curiosity. Not that 150 grain don't shoot well. If you push them fast enough they will stay ballistic at 600 yards. If your barrel is a 1:10 or 1:12 twist, it will put 150 grain match bullets in a knot at whatever distances you can hold them.
Now if you are talking 152 grain pull down bullets, that is something else. Someone can look up the spec, but those are maybe 3 to 4 MOA bullets. There is absolutely no need to make match grade bullets that will shoot in machine guns, or, service rifles.
An excellent load, considering the gas system on a M1a, is a 150 SMK with 42.5 grains IMR 4895.
I want to give an honorable mention to the 150 grain Hornady FMJBT bullets. They are one of the better 308 FMJ's on the market, and held the ten ring, more or less, at 300 yards in my M70 PBR.
Accurate Arms AA2520 had a following in the M1a. Accurate Arms blended this ball powder to the same pressure curve as IMR 4895. Since it threw better, that appealed to those who believe that throwing better means shooting better. It shot well enough, but left a lot of residue in my gas system. Since I purchased 8 pound kegs of AA2520 for $54.00 on Commercial Row, I ended up shooting a lot of AA2520. Wish I had purchased even more AA250.
