[Myrddin]

Most benchrest rifles are too heavy to shoot from anything but a machine rest. They are exceptionally accurate, but that also depends on the skill of the shooter in hand loading very precise and consistent cartridges. The brass, powder and bullets are weighed to be the same within a lot. 5 rounds in a "bug hole" is considered a good performance.

A heavy rifle has a few advantages. Less felt recoil is primary. The extra mass of the rifle can also improve accuracy by limiting the affect of the moving mass of the hammer between the time the sear releases and the hammer strikes the firing pin. The down side is that you really don't want to carry a real heavy rifle in the field for hunting. There is always a trade-off between a felt recoil and weight.

[oldenuff2no]

Myrddin
I am a gunsmith, and I build and shoot rifles in the “light rifle” category at longer distances.
A light rifle by their definition is in the 12# range. I've shot shoulder to shoulder with many competitors and I've never see a single one of them step up to the line with a 7# rifle. I can get rid of recoil without adding a lot of weight with brakes or mercury recoil arresters. The heavier rifles are much easier to hold steady in all of the mandatory shooting positions. Bench rest is not the only long range shooting sport. I also build and shoot wildcats so I do a bit of reloading.