Ok folks, I'll pretty new to the air gun world so I'm a bit ignorant to some of this stuff. But due the wealth of info from the wise members oh this and another forum I think my learning curve has been pretty steep.
Anyway I bought a used bt65 off of the classifieds board for a buddy and he wanted me to get as much out of it as I could with the ability to shoot a full mag on a nice bell curve.
So after much reading, I decided to jump in head first.
Here is a list of mods
I made a longer bolt the hammer spring adjustment and ran it down till it would cock and then backed out off 1 turn.
I put brass screws in all the ports of the valve and then drilled a new hole in line with the transfer port.
I drilled the transfer port and barrel out to about .260 (don't remember the exact measurement)
I turned the valve rod down to .131
I drilled the seat hole out to about .280?
And here is a 6 shot string
Shot. Bar. Fps. Ft/lbs
1. 200. 846. 128.8
2. 191. 878. 138.7
3. 184. 875
4. 177. 860
5. 170. 856
6. 162. 840
156
So my question is, should I stop there? It seems to me I still have a lot of air left. But from what I've read I think that's about all I can get out of it?
Anyway I bought a used bt65 off of the classifieds board for a buddy and he wanted me to get as much out of it as I could with the ability to shoot a full mag on a nice bell curve.
So after much reading, I decided to jump in head first.
Here is a list of mods
I made a longer bolt the hammer spring adjustment and ran it down till it would cock and then backed out off 1 turn.
I put brass screws in all the ports of the valve and then drilled a new hole in line with the transfer port.
I drilled the transfer port and barrel out to about .260 (don't remember the exact measurement)
I turned the valve rod down to .131
I drilled the seat hole out to about .280?
And here is a 6 shot string
Shot. Bar. Fps. Ft/lbs
1. 200. 846. 128.8
2. 191. 878. 138.7
3. 184. 875
4. 177. 860
5. 170. 856
6. 162. 840
156
So my question is, should I stop there? It seems to me I still have a lot of air left. But from what I've read I think that's about all I can get out of it?
