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.

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.

Crosman Model 99 Reassembly, Part 1

Back to the Model 99…

I got out one of my sets of Crosman 357 parts:
38-128 End Seal and the 38A027 Pin (Piercing pin)

I reassembled the valve with the original seals in place, as I’m more concerned with functioning at this point than leaks. If it functions & feeds but leaks then I’ll address that afterwards…ominous foreshadowing #1

As I guessed, the Crosman model 600-29 ring is the part used in the Model 99. As always there’s an exploded drawing up on the Crosman site. The ring is worn but I figured it would work for testing.

It was a little tricky to figure out how the parts were aligned, After a few tries I got it right.

Test fitting the assembly.

Another view.

Lever fitted in place, it was a bit of a puzzle to get it in, requiring me to retract the feed mechanism while keeping the parts all in place. I suppose I could put all the parts in at once (and may try that when I reassemble it again…ominous foreshadowing #2)

Trigger and valve in place.

The barrel in place.

Now how to shoehorn the extremely flexible magazine spring into the recess?

Happily I noticed a small hole drilled in the nose of the rear guide, which allows you to hold the spring back with a small drill bit. There’s a helpful notch cut in the receiver for just such a purpose.

I realigned the spring end so the cut end wasn’t preventing the halves from being reassembled.

This shows how the drill bit retained the spring. I just pulled out the bit and the spring expanded in place.

This is what happens when you don’t pay attention…piercing screw was reversed. So I had to disassemble again and flip it around.

Which is good as the exploded drawing says to set the length of the barrel beyond the nut to 17/32”

Presumably further adjustment and locking can be performed from the underside.

The rifle feeds and shoots! But I can hear an extremely small gas leak so I’ll have to tear it apart and make a new exhaust valve seal as well as inspect for any missing parts as the diagram of the valve is somewhat different from what I have.

I was somewhat disappointed to learn that the rifle only cocks to the low power setting with the lever, for full power you have to thumb the hammer back manually after cocking.

The wear on the cam ring means I have to be deliberate when cycling the action, giving the shuttle a little oomph so it will pick up the pellet.

Crosman Model 99 Rifle Disassembly, Part 3

On I go…

Two more screws on the left receiver half.

Removed.

The barrel comes free.

I assume this nut is to adjust the gap between the pellet shuttle and the barrel.

The pellet cam rod, shuttle, etc.

The shuttle does not have a setscrew to lock it on the rod the way the model 600 does.

Valve assembly.

Spring on the end of the valve stem extension/transfer rod.

It slides out of the valve assembly.

Piercing pin nut.

Removed, the mesh filter comes out as well.

Piercing pin parts.

The seal is a metal ring with a rubber center. Odd. In theory I should be able to use the piercing pin and seal used on the Model 38 pistol, I hope.

Valve stem housing.

Unscrews…

Valve assembly.

Exploded.

The valve seems to be the same as on the Model 38 revolver.

Seal inside the nut.

This plastic piece is loose, but retained by a staked steel washer. I’m going to keep it in place, unless forced by circumstances to replace it.

Now to clean and get together some replacement parts & seals.