FX Barrel In A .22 M-Rod (Help Please!)

[Airsnipe]

I put an FX Smooth Twist barrel in my .22 M-rod. The FX barrel is .55 OD and the stock barrel is .436 OD and I wanted to keep as much girth on the FX barrel as possible so I machined the breech out to .5 (didn't have a .55 cutter) and turned the barrel down to fit. As you can see at the breech end of the barrel I turned it down to the stock OD which made using all the stock stuff like the transfer port tube and magazines much easier. I cut the barrel to the same length as the stock barrel so I could use the stock shroud and components. I had to machine out the shroud mount near the breech block and I made a new piece for the muzzle end. Everything assembles like the stock configuration.

I did not want to go with an o-ring in the breech end of the barrel for a few reasons so I decided to put an o-ring on the bolt instead. So I made a new bolt with an appropriate sized o-ring. But I am having an issue with this point of seal. I do not seam to be able to get the breech end of the barrel to fully seal at the bolt. The o-ring is tight and takes a nice amount of force to push the bolt in all the way. It was much smoother but when I first shot it, I got a little puff on my cheek. I decided to change the o-ring configuration to make it as tight as possible just to make sure it would seal and it still leaks. Not much but it does. Can't really feel it when you shoot but if you put tissue paper over the breech it moves during a fire. I have no idea if the stock barrel configuration leaked like this as I never noticed so never checked. Should I be getting a 100% seal here and if so, any suggestions on a solution? I cant imagine the stock barrel and bolt sealed considering how tight the o-ring is now and is still leaking.

[Airsnipe]

Thanks For The Help Guys 

[rsterne]

Not sure why you changed the bolt sealing setup, I use the O-ring inside the barrel whenever possible, it seals better IMO, and it doesn't get messed up sliding through the MRod magazine, which is why Crosman chose it IMO....

When you shortened your FX barrel, I assume you shortened it from the breech end to leave the short choked and rifled portion intact?....

Bob

[Qwikrnu]

Everything looks like it should work. I'm wondering if a little stiffer o-ring might help. Try a Viton Extreme just to see what happens.....

[Airsnipe]

Thanks for the comments guys. 

Bob, I did not have a tool to cut the oring grove inside the barrel. I figured I could make one but putting the oring on the bolt seemed easy enough and I did not see how it would be any different in sealing (still don't) but I did think of it going through the magazine which it actually goes through pretty nice so I was not that concerned. Plus being cheap and easy to replace I figured no big deal. I also figured it was one thing the pellet did not have to get pushed through going into the chamber which I figured would be a benefit. The way it is now, the pellet goes in nice and smooth and the only "obstacle" the pellet has is the transfer port hole.

Can anyone show me a tool that would be used to cut the oring grove inside a .22 barrel? If I cant get the configuration I have to seal or if I have issues with the magazine, than I will cut a grove in the barrel and go back to the stock bolt.

I am using a Viton 70 durometer as that is what my place in town had on hand. I ordered some Viton 90 durometer, so I will see if that works. I also got some quad rings.