hi im interested in adding a door breacher for my h&r pardner pump a (remiington 870 clone). i would like to know if this feaseable to do myself are there any online guides? or maybe how much this would run via gun smith... probably wanna do diy, i have experience with ar and saiga builds...

If it has Rem-chokes you can just screw in a breaching choke.

 

 

This is just one example there's loads of stuff out there: http://www.midwayusa.com/find?userSearchQuery=breeching+choke

its the regular 18" hd barrel so im not sure if its choke capable. i have it set up like this now but my plan will be to also add an extension to my tube and probably go back to a normal stock...