Sunday, January 11, 2009

Fixing a Stripped Powerlet Screw Thread on the Crosman 38T

So I had a few minutes of free time and decided to do some plinking in the back yard. Went to charge my .22 38T with gas and somewhat terrifying "whoosh!" all the gas shot out between the cartridge and the sealing unit. After calming down a bit I checked the pistol and found the powerlet screw thread in the frame was stripped. It allowed just enough pressure to pierce the cartridge but then would move from the back pressure. Darn.

You can see the aluminum in the threads of the powerlet screw (#38C-045).

I carefully pried off the cup (#38-131).

You can see how the internal threads are stripped.

Lots of aluminum wrapped around the screw.

So I drilled out the hole to a letter "Q" drill.

And tapped it 3/8"-24 (fine thread)

I turned down a piece of steel to 3/8", drilled and tapped for the 1/4"-28 thread of the powerlet screw.

Then tapped it 3/8"-24

Threads...

I put a very shallow screw driver slot in the end.

And parted it off to length.

Looks good? I then deburred it all over.

I used red loctite to make sure it stayed in place and screwed it flush with the frame.

Inside the frame.

I pressed the cup back on.

Looking at this I wish I'd refinished the end of the screw...that the slot is so abused can only mean someone reefed down on it with some force, which is probably why the threads ended up stripping. Well, I'm the one who only buys used guns...so it's par for the course. You only need a tiny bit of force to seal and pierce the CO2 cartridge, which is why the manual (.pdf) says to use a coin, not a screwdriver to pierce the CO2 cartridge!

The repair seems to have worked well, although I'll check it nervously every time I charge the pistol. I am happy that I was able to resume plinking, this pistol is great for knocking over tin cans.

1 comment:

Anonymous said...

Hello,
I have enjoyed your blog for years & have learned a lot from it.
It has come in handy on several airgun repairs.
I also have a 38T with a stripped piercing screw, that also needs seals. It is very sentimental to me, & I would like to have it fixed. Someone recommended a hela-coil as a repair. Would you recommend this as a repair option?
Would you be interested in fixing my 38T like the one in your blog?
Please email me at cruiservlx@hotmail.com
I don't see a way to contact you.