That's why most of us Handiholics have more than a few receivers. If a particular barrel won't fit one receiver, it might fit another. That's the easy way, the other options are as jpshaw pointed out, fit it yourself, or lastly (the most expensive way) send the barrel back to the factory with the receiver, and have them fit it.
I personally have never had to "fit" a barrel, since I have more than "one"
receiver, I just try the barrel on the various receivers, and usually more than one will accept the barrel. Then it's just a matter of which barrel fits which receiver best.
Just understand that high pressure rifle barrels
DO NOT go onto shotgun (SB1) receivers, they need to be fitted to rifle (SB2) receivers. Read the FAQ's, and you'll soon get a decent understanding of how to do the fitting. It's not really hard, I just never had the need to do so.