1915 carl gustav m96 6.5x55

hi all i recently obtained a carl gustav swede m96 mauser 1915
i really didnt know to much about old military firearms
its been sporterized , i apologize if ive offended any one but like is said ive learned that this is quite frowned upon.
anyways if i could ask a few ?s it would be appreciated ,the barrel is 23.5 " ramline syn stock
timmney trigger and saftey the serial is hk 337xxx all numbers match except the orginal stock
but help me understand under the barrel close to the receiver there is a letter co with two dots above the o also what looks like a crown and and a B its hard to read
sorry
but any help is appreciated

Should be proof marks from the swedish military.Crown is usually stamped all over lots of parts for swedish rifles.maybe google swedish proof marks and you can research them yourself. Also pictures are 1000 times easier to identify then a description. 6,5x55 is a great caliber to get into shooting sports. Sporterization is a bit frowned upon if you do it yourself to a collectable or perfectly fine rifle but you bought the rifle like it is.so no harm or blame to you.Even some credit for you to rescue it and use it or even restore it later on if thats something that interrests you.