Is this a little 5 shot 'Break Top' Revolver ???.......Resell on these is never great and you really don't see them going for much over a $100 Bucks......It has more value as a family heirloom.

My understanding is the old H&R closed down in the 80's.......Then New England Firearms(NEF) picked up the line making their own versions which isn't going to do you any good.

Try 'Gun Parts Corp'(Or Numrich ???).....They used to be the go to source for old and antique guns like this, Next try Sarco......But my money would be on Gun Parts Corp to have it.......Finding parts on their site is hit/miss, May need to contact them 866-686-7424 or holler back at me with a model/serial - I have one of their old catalogs with schematics.....The H&R line was pretty convoluted.

Sometimes these old parts require fitting to get them timed correctly and proper lock up......So if your not well versed in revolver work seek a 'Smith.

(If I've made any errors someone will be along to Fact Check me(LOL).....I don't research this stuff : Rather I pull it from my sometimes flawed memory and experiences)

Absolute bummer.....If Numrich(Gun Parts Corp) didn't have it your on a 'Snipe Hunt' for sure.......I still have those schematics for most old H&R if you want to PM me the Model/Serial and I'll try and post it up.

Your only next options I see is to seek out a 'Smith(s).......Sometimes they may have the part, Or a part that's close enough they can modify to work just laying around in the shop.

Or

From time to time I see old broken Revolvers like these up for Auction on 'Auction Arms' as parts guns.....But mostly worn out including the parts on them.

If your friend isn't wanting to put any money in it.......Then it's an heirloom and wall hanger.