Somewhere on the barrel it will be stamped with Caliber. Probably under the handguards. The "multi" on the lower is so they don't have to set up a stamp for all the different calibers their lowers go on. Not an expert, but pretty sure you could swap out the lower with any upper, like 300...
Item Name: SW 22A
Location: Dahlonega
Item is for: Trade Only
Trade Value or Items Looking For: Looking for a Heritage Rough Rider
Willing to Ship: No
Bill of Sale Required?: No
Item Description: Smith and Wesson 22A 4 inch Two magazines,box and paperwork. Has a couple dings on bottom of...
If you got to the store finder on the Walmart site and search for local stores, the results will come up with a list that includes the store numbers, and a map.