Sure, just make sure you clean your 12ga barrels real good before shooting 12ga out of them. Otherwise the ring of built up carbon and plastic can bulge your barrel when you shoot a 12ga shell out of your gun.
Even if it hasn't happened yet, do you want to be the first? The same advise is given EVERY time someone asks about shooting tubes that are shorter than the barrels.
No, I don't have any first hand accounts of this, but then again nobody I know shoots tubes that are shorter than their barrels.
I do have a friend who bulged a tube because he cleaned from the choke end and chamber end with a short brush, and pushed all the fouling to the middle and failed to clear it out before shooting it. He called Briley and explained his predicament, and before he could explain how it happened, they asked him if that's what he did.
I suppose you could call them and ask if they'd ever heard of anyone bulging 12ga barrels after failing to clean out the carbon/plastic buildup, and I'll bet they have.
I'm going to go with Skeet-man on this one. I have a couple sets of 26" tubes and I shoot them every now and then in my 30" Browning. When I'm done it gets the solvent and wire brush treatment. It works fine but really leaves a carbon ring inside the barrel.
PS.......I have one 3 ga. set of 26" tubes for sale. Briley Lightweight with 4 choke tubes per ga.
I have shot 30" tubes in 32" barrels and always clean the barrels when you are done shooting with tubes installed. BOTTOM LINE FROM A SAFETY STAND POINT -WHY TEMPT FATE? NO THANKS!!!!! TAKES A WHOLE 2 MINUTES TO SCRUB THE CRUD FROMT THE 12 GAUGE BARRELS.
I have shot ovwe 4000 sub gauge loads this year in sporting clays tournaments. Almost all were fired in Seminole Chambermates, Briley Sidekicks or a set of full length tubes that I cut down to match the sidekicks. I have yet to clean my barrel after shooting any of them. One round of 12 gauge cleans them right up. Maybe I am just lucky, but most of the guys I shoot with who use short tubes do exactly the same thing. I have yet to see any barrel problems.