Hello Pauly67 and welcome to the Forum from Virginia;

The grips that came on my K22 Masterpiece (s/n 905) are called Magnas. As I posted if I'm shooting this gun I usually use some "football" relief Targets.

You inherited a very nice K 22 Masterpiece from your Dad. If your serial number has a K prefix, then the s/n 165XXX does put that gun about 1952. I personally do not think those grips shipped with that gun in 1952 (or whenever it did ship....only a Factory Letter will tell you when it actually shipped and where to).

The way I understand it from reading SCSW 4th is that K frame guns starting mid to late 1950's were available with "football" Targets. The football shape is actually a cut-out because the extractor would hangup with spent shell rims hitting the left panel thus putting wear on the grip itself. Obviously this was not the case with 22's (rim fire) but was a problem with M&P (later Model 10), and other 38 Special (model 14, 15) and also the 357 Magnum (Model 19) which are also K frames. By the mid 1970's grips like yours started to be available and these have the big cut-out specifically made for speed loaders, again...not necessary for a 22 but essential to LEO's and Agencies running wheelguns for duty in centerfire calibers.

The football relief Targets I have came off an older early 60's Model 14, but fit like a glove on my 1947 K 22 Masterpiece so I use them to keep the numbered to the gun original Magnas safe and secure.

Keep yours too...…...the speed loader grips are always in demand by other Collectors and your Dad evidently liked to punch some paper and those Targets do give a little better control in my opinion.

__________________
Charlie B
SWCA#3083, SWHF#570