Hi, I have a pardner pump with a 28" barrel. I'd like to get an 18.5" barrel for home defense. according to the H&R website you have to send your receiver in to have a barrel fitted to it, and you can only get a 20" from them. Does anyone have ideas about where to get a 18.5" or any info on building a spacer to adapt a 870 barrel? H&R says there are headspacing issues. Any info on the subject would be greatly appreciated.