Hi ,It is not a modern action.It is a forged action 2 line address ballard made by marlin in the mid 1891 a #5 action .The consensuis on the block is that the ears that are on each side of the hammer are for strenghtening the breech block for the improved 219 zipper chambering.

The 219 zipper mash imp is a dead ringer for the 225win which came out in 1964 with a smaller rim to fit into the standaerd bolt face ,hence we concluded it was made pre 64ish in the era of the rifle builders would use the old black powder rifle to make single shot target /varmit rifles for bench use

I tried to figure out who built it as the breech block is a full out custom and the but stock fits over the action to make use of the pistol grip.The smith/stock maker did not leave any signature of who they were .

And the one line to 22lr is an earlier #2 cast action that was originally a 38 rf that is considerably a WEAK action and would possibly granade using higher pressure

If anybody reconizes who the work can be attributed to ,I would welcome any info

tks Peter