New child adopted today. Lithgow No2 Mk IV. .22 Trainer.

[Bruce_in_Oz]

The magazine case appears to be a "No.3" pattern introduced as the first magazine specifically for the Mk7 .303 ball ammo There was originally a number "3" stamped into the back rib. Many of these magazine cases are themselves converted from earlier No1 and No2 cases.

It was superseded by the more familiar "No4" case which did away with the riveted stop clip at the front right and spring lip on the LHS. All of this magazine fiddling was a result of the introduction of the "pointy" Mk7 ammo, which would not feed properly from a magazine set up for the old Mk6 and earlier round-nosed stuff. Another example of the rifle being built / adapted to the ammo, not the other way round.

On a No.2, being a single shot, none of this matters as the (empty) magazine case is just there to catch the fired .22 brass and keep rubbish out of the action.