Any H&R Topper M48 gurus?

[Snal~]

I have a couple of old M48's, actually, a mostly complete 12ga and the other is a bare receiver.
The mostly complete gun is an F prefix which dates it as a 1945 manufacture.
The bare receiver has no serial number on the side, but has "L 1948" on the side of the tang under where the stock would be.
"L" is listed as a 1951 manufacture, so the following "1948" is confusing, unless that just happens to be a serial number rather than a date.
The only noticeable difference in the two receivers is that the L 1948 is scalloped behind the breech face, as you can see in the pic. Maybe
this indicates that it was a rifle, or perhaps a .410?
Anybody have a clue?

 

[ronn47]

@Snal~
Looking at pics on GB shows a 410 with the scalloped frame and 12 & 16 without the scallop.

 

[Average Joe]

While it’s not his specialty, @NiceOldDouble might be able to answer your questions.

 

[Snal~]

After removing the stock on the one with a serial number, the tangs are also different, looks like the L 1948 would take a different mainspring assembly.

 

[Snal~]

I disassembled the M48 and there was no evidence of a firing pin spring, not even rusted remnants!
I can't find one anywhere online, so I guess I'll try to make do with a generic spring of some sort,
I have no idea what size it should be other than being able to fit in the hole, and I'd imagine it needs to be relatively light
as the hammer rests back away from rear of the firing pin.

 

[ronn47]

I disassembled the M48 and there was no evidence of a firing pin spring, not even rusted remnants!
I can't find one anywhere online, so I guess I'll try to make do with a generic spring of some sort,
I have no idea what size it should be other than being able to fit in the hole, and I'd imagine it needs to be relatively light
as the hammer rests back away from rear of the firing pin.

Ink pen spring?

 

[Snal~]

Ink pen spring?

Probably too small, needs to be roughly 3/16"+ diameter, and probably about 5/16" long. Pic on gun parts looks like a very light spring.

 

[Snal~]

Boy howdy! The guts to this thing look like they are caked in tar!