Brownells Montezuma, Iowa
Google Remington scoremaster model 511. Several websites have information on this .22 firearm.
Brownell's Montezuma, Iowa for around $15
Try e-gunparts.com
Brownells Montezuma, Iowa
50-250 USD
brownells has magazines for around ten bucks
check the date code stamped on the barrel. Remington Society of America, Manufactured Date link has the details.
Means it was made in February 1942. See related links.
I bought a Remington 511-X (1964) this week at a pawn shop. I paid $175. There was a copy of a gun Blue Book on the counter, maybe not the latest edition, but it listed the 5411-X at about $175 for 80% finish, IIRC.
The manufacture date on the gun itself is WTT. The W indicates the month of August and the TT indicates the year of 1948. Hence August 1948 is the date your model 511 was born.
In Excellent to MINT (LIKE NEW) $150-200. They are an older inexpensive plinker.