i'm going to bed my rebarreled M 700 Rem. in a hs precision stock. I've already opened up the barrel channel for the 1 1/4 barrel, but I was wondering about all that barrel weight on the action. I was going bed the first 4 inches9 mostly the chamber anyway, but was wondering what a barrel block is for?

In a barrel block system the barrel is clamped in blocks and the action is free floating. The advantage is that by clamping the barrel in the blocks that portion of the barrel which is free to vibrate is reduced. It has been a common method for building unlimited guns for years. Regards, Bill.

To add a little to Bill's excellent post----

Barrel blocks are big, heavy, and best used on a pure targer rifles. Much the same effect can be had without extra weight or bulk by doing a "glue-in". The barrel is bedded in epoxy WITHOUT release agent. The action is left free-floated.

Be aware that to get the best accuracy out of a glue-in or a block bedded rifle you MUST use a multi-lever target trigger. A two pound trigger pull will cause vertical stringing by bending the action and causing a tuning fork vibration when the sear breaks. Two ounces of trigger pull or less doesn't do it.