If you are trying to get away with 28-bore empties, be SURE you are shooting a Mark III with the Steel barrel and the IMPROVED BREECH LOCKING-BOLT.
A friend here was shooting modded 28s in his Mark II* (iron barrel, pin-type breech-lock) and the thing tried to go full-auto on him: hammer was slammed back to half-####, breech-block OPENED and the case EJECTED in a cloud of smoke and flame.
That shot cost him $320 for a new pair of glasses. The powder-burns healed okay.
I have the casing here. It is well and truly scrood.
Be safe!
Have fun!
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