Few things in life bring such pleasure as a four inch five screw 44 Magnum!
Just added your serial to my growing four inch 44 database.
There are several interesting things about the early four inch 44 Mags that make them very unique as well as the timing of their introduction especially when putting it in comparison to the other big new SW model introduced just around the same time being the Combat Magnum.
Both early examples have the 6 groove tangs, unfortunately no 5 screw Combat Magnum exists because it was introduced as a 4 screw in early 1956 where the four inch 44 was introduced as a 5 screw and (except for two in my notes ) really began to ship out months later in Dec 56.
Another interesting tidbit is that while there were under 1800 six groove Combat Magnums prior to the 10 groove change the number of 6 groove four inch .44 Magnums is less than half that.
One other oddity is that the 44 Mag was introduced as a 6.5" initially then as a 4" afterwards where the Combat Magnum was introduced as a 4" and a 6" didnt appear until some (7 or 8 ?) Years later, probably because the CM was intended as a duty weapon where the 44 was likely intended for hunting and field use.
On a side note there was a post recently about a custom ordered four inch .44 Special that was built right around the time the .44 Magnum was being produced which makes a great comparison, heres a link if interested:
The 44 has not been carried that I can tell and shot little if at all. Excise tax of ten percent was charged so no affidavit was filed verifying the order was for law enforcement thus eliminating charging the tax. The 44 looks like it spent the last sixty-nine plus years in a sock drawer

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Bill