mauser es340b questions and parts sought

[mosin46]

just got one of these at a local show. single shot,groved rec,lt side gas port. the front sling swivel stud which goes into the barrel had me stopped. finally got it loose with A LOT of torque. a surprise as i had no idea of the setup. would like to replace it with another of same. i bet way LOL on that. anybody know of scource? have looked about everywhere. thinking about removing it as i might shoot better with less hard contact of barrel and channel. anybody know from shooting one? torque on action screws? i am stating with 25" lbs. it is factory pillar bedded,so can increase a bit. who would have thought that on a 80+ yo rimfire rifle? my serial # is 17xxxx. so,am thinking later production. 1937? all i found on searching docs on line were 14xxxx #s. thinking on removing rear sight to aid in lower scope mounting. not sure how. have looked on line and will look again,but looks permanently attached. can/will do pics if wanted once cleanup is finished.