Shooters that reload micro-adjust bullet seating, test different primers not to mention various powders in incremental weights. But all this prep assumes you can shoot perfectly off your rest using a consistent technique. I use a Bald Eagle rest with various leather bags front & rear. I also use a Bull-Bag sometimes. I do get some stares sometimes when I'm shooting some old beat-up rifle nested neatly in my polished metal-flake rest that has um-teen adjustment knobs!
Here is a trick I learned from an accomplished benchrester that was in a competition slump. Set up a white target with just a small dot to aim at. Depending on your scope, set the target at a range where you can see the dot & crosshairs clearly. Now dry-fire from your ideal rest set-up using your best technique. Watch where the crosshairs end up after the firing pin falls. If all is perfect, the crosshairs will still be on the dot. That's the goal. (BTW: this helps reinforce non-flinching too). This allows you to refine to your rest, the way you sit, how you hold the back of the rifle, the front of the rifle, the trigger pull, etc. You can experiment & evaluate. Sounds easy & often is very surprising. It's no surprise why many benchrester's shoot "free-recoil"!
Just FWIW.....
I picked up a $30 Caldwell plastic shooting rest and let me just say, I HATED IT! It never felt steady, jumped all over while shooting, and wasnt the easiest thing to use. 
