Originally Posted by
super_hunt54
Could be Barnes, never cut one open, just know it's some form of foam product and gel foams were pretty much the norm in recoil reduction pads.
The reason for asking about sorbothane is, its probably the top vibration and shock product. As stated, I did considerable testing of the product for GM when it first appeared years ago. Testing indicated it was superior over all gels and foams, including all other shock reduction materials. It was so highly regarded, that at one time it was written into one of the contracts between the UAW and GM. It wouldn't surprise me if many of the recoil pads weren't made for the manufacturer by Sorbothane.
All I know is that PAST works great!
http://www.sorbothane.com/material-properties.aspx