B40 Making a breech seal

B40 Making a breech seal

Joined: August 5th, 2006, 11:55 pm

March 11th, 2007, 4:56 am #1

Bought a piece of Polyurethane rod, Shore 75D from McMaster-Carr.

I made the new breech seal longer and got rid of the spacing washer that were under the factory seal. I could have used the factory seal that had popped out of a used B40 that I had purchased, but wanted it as a sample for future repairs if needed.

The 1 inch OD Polyurethane rod was placed in the chuck of my lathe.

A router was mounted on the tool holder. A 3/8 inch carbide wood router bit was used to cut the OD to size to fit the compression cylinder. A hole was drilled into the rod to allow the air to pass through and finally the router was remounted as a boring router with a 1/4 inch carbide wood router bit. The breech hole was bored to depth then the router was swung to 15 degrees to cut the final entrance lip.



Have Fun!
Chris

http://www.klickcue.com/air_rifle/b50_5 ... b50_51.pdf
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Last Publish Date 2-04-2007
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Joined: August 5th, 2006, 11:55 pm

March 11th, 2007, 5:07 am #2

For you guys that have B40s, unscrew the hex head compression tube end and expose about 5 screw threads. Put some blue loctite thread lock on the thread and screw down tight.

Don't remove the comp tube end completely because there is a fine o-ring at the base that forms the pressure seal. You will never be able to use it again.

At some time in the future, your comp tube end will unscrew and you will not be able to close the breech.

The problem with the above rifle and the seal was the comp tube end was unscrewing from the cylinder. The original owner didn't want to mess with the rifle after the breech seal came out.

Have Fun!
Chris

http://www.klickcue.com/air_rifle/b50_5 ... b50_51.pdf
Please Right Mouse Click and Save
Last Publish Date 2-04-2007
Reply
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