Originally Posted by CalTeacher
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.
There are several issues which go into intentionally placing a particular round in a particular spot.
Imagine a flashlight beam coming out of the muzzle of your gun, like a cone. Of course you have to keep the beam on the target. That's all about fundamentals. On the other hand, you would want as small a beam as possible once you realize that having the beam on the target isn't going to get the round on target... instead it's the area within which your bullet can randomly land.
I would much rather have a very small area in which my bullet can randomly land than a larger one. Pistols, unless they're in a rest, won't make a difference. That's why I don't bother trimming. In a benched rifle, on the other hand, will make a difference. For me, even a fifth of an inch at 100yds makes a difference. Will trimming the brass (changing the pressure, and therefore likely the height of the shot placement) for that purpose make a difference? Absolutely. I won't be going without brass trimming in the future.
And... when it comes down to it... prepping brass is part of the fun of reloading. I won't be doing it in pistol, but I'll always do it (even for plinking) for rifle.
So.. I think we're agreeing... we're just talking about two different things. I'm answering the OP's third item about it making a difference in rifle shooting. You seem to be sticking more with the pistol aspect.