I use a past mag recoil pad for all centerfire bench shooting, $35 well spent. I still get sore after shooting big bores, but no more bruising.

Wacking off 1" of barrel will cost all of 30 fps, not even worth worrying about. It may even reduce muzzle blast slightly by getting rid of the ports.

That rifle is either too light, or its stock doesn't fit you properly.
Quick fixes include installing a new recoil pad or wearing a PAST Magnum Recoil Shield.

The M-N-P may add to your perceived recoil, but try one or both of the other recoil attenuation devices above.

George

Ray, I actually thought about cutting the barrell when I first saw this gun. That would take it down to 21 inches. I like a short barell but I dont know how efficient the powder burn would be on a 375 in that length. Any help?

Saw a picture of something called a "Lead Sled" from Midway in this month's American Rifleman. I'll post a review after I use it for a while. Scope zeroing big bores from the bench rates right up there with getting teeth yanked and watching "chick flicks" IMO.
JCN

Bench shooting anything much above the .338winmag is work for me. I use a Past pad, elbow pad on my R. elbow & good upright position @ the bench. It also helps to hold the forearm w/ your hand to keep the scope away from your eye. The more you shoot it the better it's going to get.

I like Magnaporing but it does seem to "enhance" the felt reward recoil. The trade off is it's really hard to get a scoped brow.