I have these
they seem to work ok but don't expect any accuracy beyond 10m from them. I mainly use them to test pistol loads or use as case gauges to check rounds. Nothing like loading up the U/O Mossberg Thunder Ranch with 44mag up top and 12ga down the bottom for a bit of fun.
X-CALIBER SET
Item Number: 970.387
Caliber adapters for use with any break open 12 gauge shotgun.
Eight adapters with a length of 8" are included in the set with the following calibers: .380 , 9 mm , .357Mag/.38SP , .40 S & W, .44 Mag, .45 ACP , .410/.45colt, 20GA.
Carry pouch included