Does anybody know the rotation angle of the 22xx breech?

[chekbone]

I was thinking of dabbling with designing a new part for my 2250 that'll place the bolt handle farther to the rear but I'm not sure of the degree of rotation. Taking a wild guess at it, from closed to locked, it seems to be between 20 and 30 degrees. Does anybody know for sure?

[JMJ in NC]

30 degrees.

JMJ

[rsterne]

You can make it greater, I use 40 deg. (sometimes 45*) on my custom breeches....

Bob

[chekbone]

You can make it greater, I use 40 deg. (sometimes 45*) on my custom breeches....

Bob

What bolt probe are you using?. Probes like the Hollow and V need a specific degree of rotation. So 30° is it? It shouldn't matter with a pin-style factory or extended probe, or does it?

[rsterne]

I never use a hollow probe, nor is that the way the Crosman 22XX breech comes.... but you are correct, if you are using one, you need to stop the lower hole in the vertical position.... If you are making your own bolt (moving the handle back in the receiver, as mentioned), then you can allow for any rotation angle you want, of course.... Pin probes don't care....

Bob

[chekbone]

IIf you are making your own bolt (moving the handle back in the receiver, as mentioned), then you can allow for any rotation angle you want.

Bob

Moving the handle back on the probe shouldn't change anything but make designing it more tedious. I made a bolt handle that just touches the main tube when closed. I kinda like the way it sits with the factory breech. I'm basically designing it based on the factory breech setup. So 30°?

[JMJ in NC]

Drawing attached - JMJ

[CraigH]

Great drawing, John.     

I always use the flow-through probe due to consistent seating of any pellet.    If you make your own bolt you can set the bolt port as needed.   

[Gerard]

I've made a few hollow probes as well, primarily for the consistent seating of ANY pellet type just at the front edge of the transfer port hole. A pin type probe works properly only for a subset of pellets, dependent as it is upon the location of the inside foremost surface relative to the skirt. I started using a hollow probe because JSB 15.89gr pellets were only going about halfway across the TP hole. Obviously not far enough into the barrel for efficiently using the air pressure, with almost half the air striking the pellet waist from the bottom in the first instant. A hollow probe spaced to push the skirt past the TP will do so regardless of pellet design. Of course you could also make an extended pin type probe, but with some pellets that could push them several millimeters forward of the port, changing initial acceleration due to excessive expansion volume behind the pellet.

With whatever bolt angle you can easily mark a hollow probe through the TP hole when the breech is not mounted, rotating the bolt closed and holding it there while marking with a sharp point directly through the TP hole then drilling and shaping that hole in the probe.

[chekbone]

Drawing attached - JMJ

Thanks JMJ for answering the question that was asked. The powermax probe does the same thing as the hollow as far as seating all pellets past the TP, but with less flow resistance, based on fps results.