I have several H&R AAC 300BO Handi Rifles and was thinking of getting a 410 barrel for one of them. I have read there's a lot of fitting involved in changing barrels and I've also read it's just a simple swap. My receivers are the later produced center fire rifle type so I'm not worried about it being able to handle any pressure differences.

Bueller....Bueller....

I really don't know, at one time I know you were only to swap barrels if the gun came with the other barrel. I do not know if that ever changed.

I know that h&r used to recommend sending the gun in and then they would fit your barrel and such. Of course they are out of business so that is no longer an option. From my understanding if you get a barrel it might work and it might require some fitting. I would look on Marlin owners forum, I think they delve into that in the nef section, but it's been a while since I have looked at all that so my memory may be fuzzy. Good luck

That was the rule. All others had to be fitted by H&R, NEF etc. I changed them with wild abandonment. Never an issue, but not a recommendation.

The wild abandonment makes me want to do it now.

Go to GO2 (Greybeards) for all your H&R needs. Those guys are truly the experts in all things Handi.

Handi

^^^ this ^^^ thats the single best resource I found on the web when I got into Handi's about 15 years ago..

how much fitting is required is really situation dependent.. I converted several handi shotguns (SB1 frame) to pistol caliber carbine length rifles (357 mag, 44 mag, etc) years ago (great, cheap "starter" rifles for kids).. sometimes a barrel would drop right onto the frame and zero fitting was required... sometimes A LOT of fitting was required..

tolerances on both barrels and frames arent super accurate on the NEF and H&R single shots.. sometimes youre going to need a shim to tighten things up.. sometimes youre going to need to remove a little material to get parts to fit together correctly (you'll almost always get them to connect, but there are situations where the actions wont close properly or wont lock up tightly which causes them to open after each shot, etc .. it really just depends..

the good news is the process is pretty easy no matter which direction you end up needing to go, and you dont need any specialized tools, etc.. just go slow, be patient, etc.. Ive never had an unsuccessful rebarrel attempt.. all have worked out in the end and made fine little rifles..