Originally posted by AGD

All good sugestions but we are way ahead of you. The stuff is the glass filled wear resistant "super delrin" but I forgot what it's called. If you mill wear rails you have no way to hold the delrin in place. You can't do a sandwitch the stainless gets too thin and a would cost a fortune.

We were thinking about trying an aluminum sleeve, most of the weight savings with none of the wear problems. See, you guys need to think more out of the box

Welp, if you have milled or extruded rails (stainless or aluminum), why bother with having delrin as part of the bolt at all? The rails would be the only things in contact with the spring and thus would take all of the abuse, so what would having delrin inbetween the rails achieve? Besides adding weight, cost, and manufacturing difficulties that is.