Bored out case here.

I guess if you want to go to the trouble you can make up one out of delrin or brass then drill it out but drilling a case out is a lot easier.

40 Rod

I also use a bored-out case but I also added a brass bushing that is epoxied into the mouth of the case to help center the case and allow it to slide on the rod more freely. I also wrap tape around the rod near the jag to a diameter large enough that the jag does not ride on the lands and also does not hit on the crown when I retract the jag. I also wrap tape around the rod near the rod's handle so that it comes up against the back of the case and restricts the tape near the jag from coming out of the bore and letting the rod drop down on the lands.

I think this covers a lot of bases (I something similar too with my between-shots wiping rod). 

I fill the case with epoxy before boring.

To add to that good thought, use the epoxy that's poured on table and counter tops for an "indestructible" finish; it flows into every crevice so nicely (just don't forget to plug the primer pocket).

Bill Lawrence

A block of delrin sitting atop the breech block to hold the brass case in place would be nice.  Adding an insert within the case to guide rod... hmm.  I have the design in mind but no talent or tools to work with delrin.

What is also nice about my setup is I can raise my block so it engages the rim of my bore guide case thus keeping it in the chamber while I am cleaning my barrel. 

JLouis