Benjamin 3030 Disassembly, Part 1

I picked this Benjamin 3030 CO2 BB “rifle” (since it isn’t rifled) up on Gunbroker. I was always intrigued by the design and the advertised ability to “drive steel bb's clear through both sides of a 5 gal. steel pail at close range”. Why I’d want to do that isn’t the issue.

The rifle, rusty and dirty.

The wood looks like it could use a refinish.

The metal is pitted so I’m not sure what I’ll do. Probably paint it.

It cocks similarly to the Crosman 700/707 which it seems to share a similar mechanism with.

That’s the end of the 8 gram CO2 bulb sitting inside the cap.

Remove the stock screw.

Simple trigger.

An old rusty CO2 cartridge.

The cartridge seals here below the neck.

All that debris makes for a gritty trigger.

Two pins retain the trigger and spring.

Rear sight.

Removed.

More to come...

Gamo PT 80 CO2 Cartridge Seal

I really didn’t know what I was dealing with…

Levering out the brass ring (I used a small screwdriver in the slots) so I could get a better look in the cavity for the seal. Notice the pot metal fracturing. I had to use gravers to remove the excess metal trapping the ring. In hindsight I suppose I could have left the ring in place.

Although with the ring removed I was able to measure for the diameter of the seal. The ring got beat up in the process. I wonder if Gamo just swaps the whole valve assembly when they service the pistols?

Drilling the seal hole.

Turning down to diameter.

Cutoff. The first one I made was about .05” thick, later I made another than was about .04” which worked better. The seal is basically just a flat disk.

Seal in place.

Brass ring pushed in. In theory it should stay put.

Testing the assembly with a used (empty) cartridge. Reassembly of the pistol was in the reverse order of disassembly. I managed to flip the “teflon” exhaust seal around and at first the pistol wouldn’t function, I disassembled the pistol several times and finally realized that I had it flipped. It now functions normally and holds gas. Once I get some clips I’ll test it out and see if there are any other problems.

Gamo PT-80 Disassembly, Part 5

Last post…

The valve assembly removed.

Detail of the piercing clamp screw. The square nut is captured by the grip frame.

The valve snaps out of the strap.

The mostly removed (by a previous owner) CO2 seal.

Hmmm… none of my other tools fit.

1/16” thick cold rolled steel…

Fancy tool…

Unscrewed.

Seal and valve body screw.

It’s probably a flat seal that deformed to fit.

Why not another pic? Odd that it came out looking orange, it’s redder in real life.

The valve stem. Seals against the red seal, when it’s knocked open gas flows from within the valve chamber, through the three radial holes and down through the valve stem.

A pretty stout return spring.

There were washers and a teflon (I’m assuming it’s teflon, could be anything) seal.

Other end showing the teflon seal.

The washers were a stack of 3.

I can’t figure out how to get that brass ring out. You can see a gap between the bottom and the ring where the seal goes. I think that the edges of the valve assembly were staked over it to retain it. Likewise I think the piercing pin was a press fit. So I’ll leave it. A new seal should snap into place if I make it the correct thickness and diameter.

What have I done? Good thing I took pictures. I'll work on getting it resealed soon.

Gamo PT-80 Disassembly, Part 4

On I go…

The Hammer mechanism is a little complex.

Notice the position of the hammer spring.

Hammer removed.

That oversaturated part is the sear? The transfer bar underneath pulls it off the hammer.

Notice the spring.

Lift it off.

The spring.

More detail of the parts, in case.

Hammer transfer unit swung into place in front of the valve stem.

Removed and the transfer bar is finally almost exposed.

Removing the valve assembly.

Now the transfer bar is free…

Headed pin pushed out through the right sideof the grip frame.

The spring is unhooked by rotating back.

Leaving this in the grip frame.

Pulling it up, careful not to lose the spring.

It’s a fairly stout spring.

Brass inserts in the grip frame.

Front view.

Plastic plugs. I’m assuming this is where a laser sight would mount on those versions that come with a laser sight.