I don't believe I'd put the sand paper in there. It may act as a spacer and actually lower the grip. Also make certain the hole in the blocks is almost the exact size of the barrel at the point your trying to grip..(of course you are gripping a parallel section of the barrel?) then be certain that the blocks can't completely close on either side of the barrel. This gap will allow them full contact with the barrel.. I've never used sandpaper, just powdered resin. It's worked well so far.. good luckl from the gunnut69
PS-- I have heard of people gluing the blocks to the barrel with acraglass to get the perfect grip...also juct to be sure, I once found a barrel that had been spot welded to the receiver. God's truth!!
PS-- I have heard of people gluing the blocks to the barrel with acraglass to get the perfect grip...also juct to be sure, I once found a barrel that had been spot welded to the receiver. God's truth!!