I am unable to locate a bolt action H&R trainer used by the USMC after WW 2. However, there was a semi-automatic rifle used by them. This was the .22 caliber H&R Model 65 Modified, also marked as MC-58. These are relatively scarce. The Civilian Marksmanship sold a few some years ago, typically several hundred dollars. Your best route will be to check the on-line firearm auctions such as gunbroker, auctionarms, and gunsamerica. If you locate one, it will need to be shipped to a dealer in your home state. Good luck.
About $100.
"P" prefix indicates 1953
1941
1940's-1950s.
Try Gun Parts Corp
25-175 usd
Have you tried a web search? Local Library? Do a web search on Harrington and Richardson Books and you will find some sources.
50-100 USD
1930's-40's.
single shot 30 30 with 32 gauge dart barrel have barrel need action
50-100 dollars
You will have to contact H&R 1871 Inc. to find out.