We have a 410 Mausburg pistol grip pump with an 18" barrel. I payed $99 back in 92, I bought for my wife to keep in the house for home security, as she is uncomfortable with pistols. Trust me, sounds just as big as 12gauge in the DARK... Fortunatley she has never had cause to need it. But I make her practice with it often any way. No Kick even with 3 in magnums.
I have considerd finding a way to carry it on the tc21. But would realy like to cary it overhead in the canopy, if I can find a safe secure way to do so. If not, I guess it will be down low some where. I don't need it for mice, I have a JR for that, he gets them quick and has fun doing it...Along with the occasional wabbit! or gopher rat... and so on. Just have to keep up his shots....
BTW I have seen a 410 pistol at a gunshop before. I would think i would fall under the pisto regs and need to be used with slugs.. Bet it would kick tooooo....