MM 2k9 and barrels

[RehKal]

Ok, the MM 2k9 is cocker threaded right?

Cause I'm confused now. I can thread in my deadly winds CF barrel into my MM 2k9 body with no trouble. But the freak back and spyder to cocker adaptor I have lock up almost as soon as the threads make. And all three barrels make up fine in my other cocker threaded markers. I'm just confused about what would cause one barrel to work and the others not, are the tolerances really that close? I know to not force them together but am now worried about being able to use a freak back with it, I'd like to have the body/barrel all annoed with the same color theme.

[Drix]

They are cocker threaded. Do you have a raw body?

[GRimm]

I actually came across the same issue with my 2k9, I have a SS boomstick back that will not thread into the body, but all my aluminum barrels thread in just fine. My guess is that the threads on the body are the very small side of the spectrum and the barrel back is on the very large side. Getting it anno'd may take off enough material of both to allow it to fit, although I'm sure if you hit up Luke he can help you out. You probably just need to run a tap down the threads once or twice, but I personally would be more comfortable having Luke do that then myself.

[zondo]

I wonder if the threads need to be chased...

I have this issue with mine, except for some barrels they will thread part of the way before I would need a strap wrench to got the rest of the way.

[RehKal]

what size threading is cocker threading?

[GRimm]

what size threading is cocker threading?

According to this thread the tap size is: 15/16" minus 46-50 thousandths

http://customcockers.com/forum/showthread.php?11909-Beginner-Autococker-Threads-Tap-amp-Die-Sizes

[luke]

If I recall correctly cocker threads were never standardized so on occasion some come up too tight.

[athomas]

Take one of the tight barrels, apply some grease on the threads, and then screw it into the body. The grease will prevent the metals from heating and sticking together and will prevent the barrel sticking in the body. Quite often, it will remove any rough edges and compress the metal in the threads a bit making them fit much better.