Not right after cleaning

[Oscar M.]

Mike, good. The string method is a very common method and with the assistance of a draw of air from a vacuum. Well done.
Sometimes cleaning will cause dieseling and the first few pellets will go astray. Mine do for about 5 shots. Then it settles back down. OM

[jaraxle1zx]

Just got my bt65 in today
This might loss of power thing when you clean barrel. there is an o ring at beginning of barrel on inside of barrel. A wire brush might cut that ring.
I took my barrel off gun and took the inside o ring out then cleaned barrel, was real easy and took longer to get barrel clean than take off and replace back.