I’m not a big fan of sub-gauge tubes. I’ve had three sets.(Kolar, Briley, std weight and ultra lights). Troubles with broken ejectors and problems keeping the tubes in place mainly. Most work best with low brass AA’s, STS and Nitro’s. The old Briley tubes did not like steel base hulls. They allegedly have fixed that issue. The weight issue can be significant although I have had unusually good luck shooting 32” tubes in my Sporting gun, finishing respectfully in 28 gauge FITASC and Super Sporting events. Weight was a tick under 9.5 #.
The best tube gun setup I’ve shot belongs to my best shooting buddy. It is a 12 ga 30” 325 Browning with barrels bored to the max by Dean Harris and the 12 gauge choke tubes fit tight to the sub-gauge inserts. I believe all the work was correlated with Briley.
I’ve shot several sub-gauge events with that gun and it handles pretty nice. YMMV.
