Saturday, August 21, 2010

Rebuild of Joe's Crosman 454

Sidetracked from the 118 magazine when buddy Joe asked me to fix a leaky Crosman 454 semi-automatic BB pistol. This is a second variant due to the loop on the CO2 piercing screw at the bottom of the grip--which means it was made right around 1980. The gun uses a 12 gram CO2 cartridge housed in the grip and it holds 16 BBs. The BBs are held linearly above the barrel. A spring loaded plunger pushes the BBs backward to the breech where one is loaded with each trigger pull. The trigger is essentially double-action only with a pull that ranges from about 5-1/2 to 6 pounds of weight.


Joe told me the CO2 was leaking from the end seal.

The right side grip is clipped to the 12g CO2 cartridge and pulls right off. The left grip is held by two screws.

Joe was right. The end seal is almost non-existent.

Removed the rear sight.

Four screws hold the frame together.

Screws removed, the right-side half lifts off.

If you want to remove the barrel, there's a small screw on the underside just behind the muzzle. It retains the front sight--which in turn holds and centers the muzzle.

Of course, the safety ball bearing fired across the room when I lifted that right half. Some things never change. I scrounged a tiny replacement 3/32" ball bearing. (Nick probably still sells bags of tiny bearings for just such occasions.)

Detached the hammer and trigger springs.

Small set screw retains the barrel in the valve. It's a 3/32". Just unscrewed it a turn.

Removed the valve anchor bolt in the left side of the frame.

Pulled the trigger pivot pin, wiggled the valve around then lifted off the hammer. The entire trigger, linkage and hammer assembly comes out as one piece. It's straightforward.

Slid out the smooth bore barrel. If you look at the breech end of the barrel carefully, there's a circlip in a groove that acts as a locater stop against the valve.

The BB follower is plastic. Look at that spring! That's exactly what I need for my Crosman 118 magazine. Think Joe would notice if the gun was gravity fed?

Some valve pics. Rear. The silver protrusion is the valve stem that gets struck by the hammer.

Top. The screw holds a spring that pivots the BB shuttle (for lack of a better term).

Screw and spring removed. The shuttle slides right out. It picks up a BB from above and as the trigger is pulled, a transfer bar pivots the shuttle into alignment with the breech. It's a really simple, elegant design. Note: There are no seals on the side of the shuttle-- just an interference fit in the valve body.

Removed the cap from the front of the valve.

Valve spring and stem pulled out.

Ah, here's that bad cartridge seal. Unscrewed the threaded retaining ring.

Used a dental pick to work the crumbling seal out.

Underneath is a standard 38T/C piercing pin and screen filter.

Here's what the crumbled pile used to look like. Crosman's part # for the seal is 38-128. It's still available and used today in the Crosman 357 pistol.

Reassembled: Screen, piercing pin, seal, retaining ring.

Replaced the cap o-ring with one that looked similar in nitrile. Didn't replace the stem seal. It actually looked pretty good and it operates with 900 psi on it--that really helps keep it closed.

Greased the shuttle's sides to help pivot smoothly and seal.

A couple views.

Oh, I lubed the valve stem seal with a little Crosman Pellgun Oil. The rest of the reassembly was pretty uneventful. I did refinish four or five of the visible screw heads, removing old screwdriver marks and rebluing. The gun gassed right up and fired 60+ shots without any hiccups. I'll give it back to Joe and he can finish giving it a shake down.

If I ever find one of these (and for the right price) it would be relatively easy to turn down 8" of 1760 barrel and shoot this with 0.177 cal lead balls. I'd imagine that the accuracy might even be pretty decent but probably not the velocity.

Wednesday, August 18, 2010

Magazine for a Crosman 118--Part 1

A quick post on a project I started well over a week ago.

I've got an old (c. 1954) Crosman 118 rifle. Got it from my grandfather many years ago. The 118 is pretty interesting as it's a 10-shot, bolt action, bulk-fill .22 cal air rifle--Hey! Just like my Marauder. Nothing new under the sun as they say? Anyway, the 118 utilizes a linear feed, spring loaded magazine. I've only got one magazine and if it ever fails, the gun will fall silent for a very long time as the mags are notoriously hard to find. Operating on the principle, "one is none and two is one", I decided I'd better have a backup--or two.

Was frustrated a couple weeks ago at not finding a readily available tube for the body of the magazine. And I didn't want to drill a 5+" hole in a piece of solid steel rod. Not fun. Finally elected to go through the (s)crap barrels and simply open them up a bit. The two best candidates were the Crosman SA6 barrel (middle) and one from a Crosman 357 (bottom).

Starting with the SA6 barrel. It's almost the exact diameter and length as the 118 magazine. Drilled out the rifling so .22 cal pellets slide through.

Used a 3/32" center-cutting end mill and slotted the side of the tube.

A pin (in the still-to-be-created-follower) will ride in the slot and act as a stop to prevent the follower from shooting right out the end under spring pressure.

A corresponding slot in the 118's receiver allows you to align the slot in the magazine to see the pellets remaining in the gun with a glance.

SA6 barrel version is gonna be the "prototype". Of course, I'm hoping that it works and I can call it good, but the extra length of that 357 barrel will potentially hold a few more pellets. Length does become an issue at some point, though, as the magazine sticks straight out the rear of the receiver towards your face.

Current issues: I can't find a long enough spring--at least locally. I can potentially stretch one out, hit the internets, or make one. Leaning towards making one, but that's gonna be a drag, as I only have manual feed on the lathe. I've got an idea kicking around.

More to come in a couple days.