I bought a old fairly rare autoloader 12 gauge the other day. The 878 was only produced from 59-62 and it came with imp cyl bore. As this is an old classic gun with only 65000 produced i will not modify the barrel for screw in chokes. Will the imp cylinder be effective say at 25-30 on no.4 shot with 2 3/4 shells for turkey. Is this gonna be effective to kill a turkey at this distance? Please advise...