That LAR8EO is a 1:10" twist barrel. Most PTRs are 1:10" twist rate, unless you have one of those PTR pistols. The M1A could be 1:10, 11, 12, who knows. Same on the FAL.
The 1:10" twist barrels will probably shoot a heavier bullet better than the 147-grain stuff. M80 Ball is 147 grain.
You should experiment.