Originally Posted by Kappy
But those are two different factors. Better ammo makes for better shooting. A better shooter makes for better shooting. Both together is even better.
Unless you are more precise than your ammo, the difference wont be worth the amount of time your spent trimming all your cases. Having ammo capable of 2" groups at 50 yards doesn't mean you can actually shoot those groups. Its like having a gun that is capable of those groups...unless you have the ability to shoot with that sort of precision, you'll receive very little payoff, if any, from the added efforts.
Go to a match some time and take a poll of how many competitive shooters trim their pistol brass.