Friday, November 19, 2010

Crosman Model 99, Driving Me Nuts, Part 1

The title says it all. I started by trying to tighten up the pellet feed mechanism, successfully. I stole the cam ring from the beater model 600 pistol.11191016

The ring binds on the cam rod.


I had to do a little operating on the ring.


Just some work on the corners and chamfering the edges. Red line shows how much metal is contacting the cam rod.


Still locks up on the cam rod.


More polishing of the corners of the cam rod and now it feeds fine, very little play.


The slow leak was bothering me though. Removed the exhaust seal. It was the opposite of pliable.


Making a new seal.


Cut off. Then installed. But it was still leaking.


The seal where the valve stem passes through the body was troubling me. I took apart a Crosman model 38 valve to see if I was missing something. That washer…I didn’t notice it in the 99 valve.


Found it.


Down in the valve was a rubber seal and a plastic sleeve.


On later model 38’s they use an o-ring but the original seal (center) looks like a flat ring. Skipping ahead, I think this might be one of the reasons I ‘m having a leak. I’ll be making a flat ring seal later to test this theory out.


The washer, new o-ring and plastic sleeve.


The valve stem is the same as the model 38 valve stem.

After taking it apart several times, making another seal, wasting about 4 CO2 cartridges, still not finding the leak (if anything the leak was getting worse), I decided to build a test unit.


Empty (!!!) CO2 cartridge tapped for an air fitting. Only about 2 threads holding it in, so I didn’t hook it up to my big compressor, just the little paint compressor.


The compressor. At least I won’t be wasting 40 cents every time I test the valve. Unless of course it leaks at low pressure and seals at higher pressures, in which case I’m screwed.

In any case, I’m going to take a break from this rifle for a little while as I have an even more complex project that I want to get to next week.


Was a kid with a pellet rifle said...

You took a little break and it's been more than a year! :-) Did you quit or just not posted the continuation?

I was looking at this because I have a Model 99 in a closet here. I haven't looked at it in decades and wondered if it would work. I presumed the rubber ring/seal around the piercing pin would be stiff and brittle and need some kind of replacement, but it seems there's other stuff that may need replacing too. I wouldn't get in to this as seriously as you do, and you have the know how, the tools and materials I don't. :-)

But thanks for the info and documenting the job, it's appreciated.

Good luck,

Nick Carter said...

I just got tired of it as I wasn't having much luck getting it running right. I'll probably pick it up again now that I have more time this winter.