You want to make a clean kill. So what should you use?
A: If you don’t point the gun in the right direction, you won’t kill the rabbit.
That may sound obvious, but at the end of the day both shot sizes you’ve mentioned will kill. Fives are fine for fairly long shots out to about 45 yards but, in my mind, they are a bit ‘overkill’ on the closer range bunnies which you are hoping to sell later at market.
My best shot size for rabbits?
I use Lyalvale Express Pigeon Specials, loaded with No. 6 shot for all my shooting. The pellet size is a good all round compromise which doesn’t smash the quarry, but makes for clean, humane, kills. I tend to use 30g cartridges through my 12 bore.
Having said that, my .410 shells are a lot lighter but, being sixes they still kill with ease out to 35 yards. The secret, of course, is to place the gun and shot pattern in the right direction.
There’s little point being dogmatic about guns and cartridges when bolting rabbits: use what you feel is best for yourself at a distance you’re confident of making a clean kill.