Re: Dry Firing
My answer has more to do with competition shooting with sand bags, but can be used on the bench during sighting in or serious LR/ULR shooting from a bench or from a bipod also.
Whenever I setup my rests on the bench, pound in the bags, lube them etc, after I settle the rifle into position I always dry fire (in a 100% free recoil hold on the rifle!!) the first couple of rounds. Here's why: If your bags aren't settled when you dry fire (after "insert bolts" and "commence fire" is called obviously), if your crosshairs jump up or left/right at all then you need to pound in your bags some more or you will get up and down in your sighters until they are settled. Also by dry firing the first couple that means everyone else has already shot their first couple of sighters and are making scope adjustments, so I'm clear to fire without doubling with the shooter next to me which can and will cause problems also.
This works if your shooting off from a bipod also. If the bipod is under sress somehow and you dry fire... you would be suprised at how far your crosshairs will jump when the bipod "unloads" from the vibration of dry firing. Then if your talking about position shooting like high power in the off-hand, there no question it is great practice.
So my thoughts are this: it is great practice not only for your shooting position, breathing/squeezing like we've all been taught, but watch for the after effect and which direction your crosshairs move to. It will tell you a lot about your position, rifle hold, and rest setup.
Hope this helps,