Barrel..

You can probably improve barrel accuracy by "fire lapping" pellets with lapping paste...or valve grinding compound (fine)...I did that to my 850 .177 barrel plus a re-crown with the brass screw/drill motor trick...LOL..

I just rolled pellets in the lapping compound and loaded them in the breech with long tweezers.(no magazine).....think I shot about 15 thru barrel...then cleaned barrel good and test fired it on target...best to test fire in no wind..