Early Crosman Model 101 Disassembly, Part 1

I bought a lot of three Crosman 101 rifles last year.

I decided to start on the top one. The one beneath it is of similar vintage but has more issues. My plan is to not restore the finish but to just get it functioning. I want a specimen rather than a beauty.

The only real problem is a chip out of the pump arm. Not sure what to do but I may just leave it.

Removing the stock screw.

The cork gasket needs to be replaced.

The cocking knob doesn't seem to be original so I'll swap with the other ones knob.

I'll need to make some tools...

The other cocking knob fits fine.

I slid the small spring that retains the pump pivot pin off to the right.

And removed the pin.

Gently tapping off the front plug.

The two parts.

The pump plunger is leather!

For the life of me I couldn't remove this pin. So I decided to leave that assembly together for fear of destroying that fiber sleeve.

Removing the rear sight.

With the cocking knob removed the bolt just slides out.

Magnetic Derrick's Crosman Bolt Hold Open

Crosman 22XX and 13XX's are easiest to load when the muzzle is simply pointed downward. The pellet is dropped into the loading port and the bolt closed behind it. Loading the gun horizontally is harder because the pellet often catches in the recess for the breech bolt. Vertical loading also helps negate shaving the edge of the pellet on the breech bolt recess, but can be annoying if the bolt doesn't stay rearward--especially if there's a scope spanning the opening. Adding a small magnet to the rear of the bolt allows it to stick rearward to the hammer cocking pin until you intentionally close the handle.

I picked this particular gun from the pile because the bolt was an especially loose fit. Removed the 2 bolts holding the breech...

Unscrewed the bolt handle, and here we are.

I want to add a magnet to this end--the end that cocks the hammer. The hammer itself actually sits below and parallel to the bolt handle. A steel pin connected to the hammer sticks upward allowing the bolt to move the hammer rearward. Once rearward, the sear engages, holding the hammer in place. Got it? By adding the magnet to the rear of the bolt, it will stick to the hammer pin when cocked, thus holding the bolt in the rearward, open position.

I was buying some supplies from Enco last week and I knew immediately what I was going to do when I saw these rare earth magnets.

I chose to use the smaller of the 2 sizes I purchased. Enco's part number: 327-6459 A whopping 30 cents each. I was feeling so spendy I ordered all of six. Check the Enco part number if you want all the specific measurements. The magnets are made by Eclipse Magnetics.

Magnet stuck to the end of the bolt.

View #2.

I chucked the bolt in the 3 jaw. No real super-high NASA precision needed. Spotted with a center drill held in the tailstock.

Center drills are short, stubby things made to be rigid as all get out. Keeps the tip from flexing and wandering across the workpiece. They basically put a starting hole right where you want it.

Spotted.

Switched to a 1/8" end mill. This will bore a flat bottom to the hole for the magnet to rest in. Flat bottomed holes are "counterbored".

Yeah, I know. You looked at the magnet specs and did the math, didn't you? I made the bore diameter 0.005" too big. It'll be OK.

Test fit the magnet. I bored to make it flush with the end of the bolt.

Another view of the end of the bolt. Magnet is magnetically held.

Gorilla Glue time. Epoxy would also be a fine choice. Just want to make sure the magnet stays stuck inside the bolt.

Last look before she gets reassembled. Note: I let the glue dry for half an hour. I decided it probably wasn't a good idea to reassemble the gun with wet superglue on the bolt.

Cocked the hammer and pointed the unloaded gun downward. Gave it some moderate shaking. Bolt stayed put. Testing complete.

You can just see the magnet in the bolt. I'm glad to have a visual to ensure that it stays put. Could've used a larger and more powerful magnet, but consider that the magnet only needs to hold the weight of the bolt and the bolt handle. If your gun has a larger and/or heavier custom bolt handle, a slightly larger magnet--Enco part number: 327-6460 would be a better choice.
Beware: those little babies will set you back 45 cents each.

Notes on Cleaning and Resealing the Benjamin 310, Part 2

Almost done...

I measured the depth of the tube to the valve face.

And the distance from the end to the pivot center.

And the length of the pump assembly from pivot center to plunger face.

And then I adjusted the length...and reassembled. All that measuring got me close, but I still had to take it apart about 3 more times before I had the pump headspace set to my liking. Anyone have a better way of doing it?

Then I went to work making a replacement aperture disc. I took some rough scaled up measurements from the Benjamin book...the threads seem to be 3/16"-40. All I had was a #10-40 die but there's only about .0025" difference between those two so I just adjusted the die to cut oversize.

Knurling...

Turning the shank...

Here's the adjustable die.

It fits!

Drilling a .081" aperture hole (#46 drill). I went big because I wasn't sure what would suit my friend best.

Boring out the recess in the front. I intentionally ran it fast so it would chatter at the bottom, hopefully diffusing the reflection.

Yes, it's screwed in backwards for this shot. Oxpho Blue is awesome stuff.

Mounted on the rifle.

Another shot.

The 310 is a smoothbore and the bolt is bored to just hold ball ammo. Kind of neat.

Well it's held pressure overnight, several days in a row. I got velocities of 590 fps using the Gamo round balls (8.2 grain) and 620 fps with CPL (7.9 grain) pellets, both at 6 pumps, which is the maximum recommended. Better to just pump it up 3 times for plinking. I'll see if it holds air for a week straight and plink with it off and on before giving it back to my friend.

Notes on Cleaning and Resealing the Benjamin 310, Part 1

Now to get the 310 shooting again...

The valve components were covered with oxides.

I cleaned them up with steel wool and a fine wire wheel.

The inlet seal was extruded and hard...I'll replace it with a teflon seal since they seem to work well.

The exhaust valve seal was also hard and extruded.

So I dug it out and de-crimped the cup.

Last time the de-crimping made the cup look rough so I decided to make a die to smooth out the cup a bit and restore it to roundness. It has an OD of the ID of the cup and a hole for the stem to fit through.

The outer die is basically a tube.

I pressed the cup though on the arbor press.

It restored the roundness.

I cleaned it up with a file on the lathe.

I used the same crimping die that I showed in the previous Benjamin resealing post.

The new seals. The right lead seal is a bit tweaked.

Two seals? Last time I resealed I only used one? That's because I missed one that seals the valve body (337 Outlet Valve Seat) against the air chamber. It was luck that it stayed in place and worked.

This shows the two lead seals needed.

I hate cleaning out the tube and air chamber. This is two Irwin bit extensions with a holder for some ultra-fine scotchbrite pad. I wrapped masking tape around it so it wouldn't scratch up the tube.

Used with some light oil it scours out the deposits without messing up the surface of the tube. I then clean everything out with paper towel wads held with a parts grabber.

For the air chamber I use oil and some paper towel held in a slotted dowel. Just keep cleaning until the paper towel comes out clean. It takes forever.