and get the bolt speed up to fast you run into the problem of out running the magazine spring and get the bolt speed up to fast you run into the problem of out running the magazine springAnd the bolt catch spring. I shoot Service Rifle High Power, and many of us use heavy loads with 75/77 mag length for short line and rapids, and 80/82 or even 90 for 600. The best solution in my experience for the AR15 system has been a Tubb Carrier Weight system and a CS flat wire action spring. More inertia to move, and a slightly stiffer spring to resist, bolt carrier moves slower but with more force, brass life ( when you use Lapua brass, brass life matters) increases, reliability improves ( most matches are no-alibi events, so if you kit fails, each lost shot costs 10 points in a game where the winners are decided not by points but by Xs). Superior Shooting Systems makes these components.
BTW, I also use the same rifle in 3 gun and steel/PRS, and bolt speed has never been an issue- hits count, follow up shot in action/precision games often are the result of misses ;>)