BT-65 Mods

[OleTomCat]

I am working on the efficiency and power mods from Bob's thread on the AT-44 applied to my BT-65.

How do I remove burrs from the inside of the barrel, without removing the barrel, when I drill out the barrel port to 75% of the boar, 3/16" for a quarter bore? 

I already have the holes plugged and the transfer port drilled, I have been holding off on the barrel port trying to figure out a way to remove the burrs without removing the barrel.

[fairly]

I'm interested. Can you link to the thread you're referring to please?

[OleTomCat]

I'm interested. Can you link to the thread you're referring to please?

http://www.gatewaytoairguns.org/GTA/index.php?topic=33903.20

[Bwalton]

Yes Bobs tune is the universal tune... After that then you want to get into this tune
http://www.gatewaytoairguns.org/GTA/index.php?topic=95228.0

[nervoustrigger]

Al,

I checked Bob's thread and maybe I missed it, but I'm having a hard time picturing how one might drill the barrel port without removing the barrel.  You mean without separating it from the breech block?

In any case, I'm usually able to reach in with a 1/8" diamond ball (from the same direction a pellet would be loaded) and round over the edges of the port.  That is, using a Dremel tool on low speed, rolling the ball back and forth lightly over the sharp edge to give it a slight radius.

If the situation prevents you from doing that, you can use a bit like the one on the right to reach in from the same direction you drilled the hole.  Notice how it's shaped like a cone with a disc on the end?  What you do is catch that little disc on the lip and debur it that way. 

I hope this helps!

[ironmule]

old tom cat
when drilling holes i a barrel or something similar put a tight fitting dowel in it and drill thru into the dowel this should eliminate the burrs for you

you can also use a small dental burr from the top side to get them out
mule

[OleTomCat]

Jason,

Yes I want to leave it in the Breach block so as not to mess with what is a good setup already.

I am going to tear it down again and open up these ports to 3/16" trying to get back up to 950 fps with the bigger pellets, probably going to have to crack the valve open to get more than that out of it...