One of the things I liked about the .450 B going in was the AR platform. I was figuring that I could add an ergo grip, an enidine buffer, a muzzle break, a slip on recoil pad and stuff my high power weight in the stock all to make the long sessions at the bench more comfortable. In general it worked out. After the first 50 rounds I also added a stick on foam pad for my cheek. It made a pretty cushy set up and 60 round bench sessions were no problem. Ugly, but comfy.
One issue did turn up. After about 60 rounds of 250 grainers @ 2,200 fps the lead stock weight had pounded itself up into the stock far enough to put torque on the buffer tube, binding up the buffer. Aparently the foam filler in the stock just isn't up to that kind of pounding over time. I tried adding additional foam in front of the weight, and then adding resiliant foam, but the same issue would re-surface, (it only took 10 rounds of the 300 grainers).
As this stock set up will not be the permanent arrangement for this rifle, and as "black" rifles are not exactly works of art to start out, I've happily drilled two holes through the stock ,and weight, and installed two flush furniture bolts to hold things in place. The weight makes a real difference off the rest and as I get older I do appreciate a little extra comfort here and there. i think if you pinned the weight from the start, before it has opened up the foam, you could get away with only one cross bolt.
BD