Pellet gun fundimentals?

I have an old Crossman pellet rifle, matter of fact, I think it is the first one they made, 1924 or so.
I use this thing, it's a great toy and very nice to look at.
Lately it seems to be giving me some symptoms of a developing problem, and I know nothing about them. It is a pump style rifle, the more you pump it the higher the velocity. How does that work?
Typically with this style of gun you would pump it up then there is some form of actuator you pull, then it is ready. At times I have to pull the actuator first or each pump results in the air leaving the rifle instantly. Other times after a bunch of pumps I can fire it, then pull the actuator and fire it again, without pumping.. I would love for this thing to work right again, continuously.
After I get past this little hurdle, we can talk about modifications..

"How does it work?" Like you said, it's a pump gun. The pump pumps some air into a storage compartment, which holds the now compressed air until you pull the trigger, when the air goes into the chamber and pushes the pellet down the barrel.

The problem is probably the seals, springs, and/or valves. If you are mechanically inclined, you can start to disassemble the gun and check the visual condition of the seals, valves, and springs. As well as inspecting for dirt, crud, and rust. Watch out for little pieces and flying springs as you start taking it apart.

If you don't want to take it apart yourself, search the web for some airgun forums and gunsmiths. Note that it may be fixable, or it may not. Parts might not be readily available, or they might, I don't know.

As moonrise said, probably an issue with dried up seals/o-rings or crud in the mechanisim. Possibly also issues with old/weak springs.

A lot of the older airguns would suffer damage if you overpressured them (pumped too many times).

The air storage part I understand, it is the actuators job that I am having a problem with..
The seals all seem to be good, it holds air for long periods and pumps correctly..
The oddity is if I pump it 10 times, pull the acuator and fire it, it works, if I pull the acuator again it will fire again, the third pull of the acuator will make it go "pfft.." then I must pump again..If I release all the air buy using only the acuator that is when it will not hold air, so, I pull the acuator and resume..
I wonder if there is a site for this stuff..

Sounds like an issue with the release valve or release valve spring where it's not ejecting all of the compressed air at once like it should. I'm sure there are sites for Crossman airguns of all types.

Your description of the actuator doesn't match how my Crosman works, but it is probably from the 1960's. My Crosman has a valve attached to the trigger. It is automatically reset when you start pumping again, so the user doesn't have to do anything.

I also have a Benjamin and a Sheridan, which are similar to the Crosman but to have spring-loaded hammers attached to the trigger. Before firing you **** the internal hammer using the rifle's bolt, then when you fire it the hammer moves forward, strikes the spring-loaded valve of the air chamber, and opens it temporarily allowing air to escape. Because this happens quickly it may not let all of the compressed air out, and you might be able to fire it again without pumping. This design does not require you to **** the hammer before pumping, you can **** it at any time.

None of my 3 require you to do anything before pumping, you just start pumping. If you hear air leaking then you have a problem with seals, and this is common with guns much, much younger than yours. But like I said your gun may have a different style of mechanism.

If you search the net you'll find lots of information on airguns. There are people who customize modern airguns to give them more power and durability. Then there is a whole wide world out there of airguns that are powered by springs, compressed CO2 and compressed air fed from scuba tanks.

Here is one of the better known airgunsmiths:
MAC-1 Airgun Distr./McMurray & Son
(Tim McMurray)
13974 Van Ness Ave., Gardena, CA 90249 USA
Phone 310-327-3581 FAX 310-327-0238 Hours-M,Tu,F,Sa 11:00AM-6:00PM PST
email: [email protected]
http://www.mac1airgun.com

I don't have the diagrams for that gun. I'd start by looking for a model number and googling it.

I can imagine from your description that the pump presurizes a chamber. The actuator bleeds a set amount of that presurized air into a second, smaller chamber for consistant firing. That chamber is sealed with a valve that is under pressure. That valve is the one that leads to the back of the pellet. Just for fun, let's call it the dump valve. If there is insufficient pressure, the valve does not seal , theu the "pfft.." that you hear.

The dump valve is the one that is opened by the pull of the trigger. If that valve is stuck open, it will allow the pressure from the pump chamber to flow directly to the pellet when the actuator is pulled.

This may be all wet, but it fits with my memories of pellet guns of my youth and makes sense.

If you disassemble it, parts will fly. Do it in an uncluttered area and clean/sweep/vacuum the floor first so you have a better chance of finding the parts.

An old locksmith trick is to work on a piece like that in a clear plastic bag. Parts that go SPROING stick around better. A dry-cleaning bag works great.

Daniel

Ok, I'll take it apart, but ONLY because you guys told me to..
It's starting to make sense now..

I had one of those Crossman combo .177 BB/pellet guns when I was 9 or 10. Would load pellets one at a time or 10 or so BB's at a time from a resevoir that held several hundred. Sold it at a rummage sale about ten years ago. Wish I still had it!

While we're talking about pellet guns, back in about the mid 1960's my older brother-in-law gave me his old Benjamin .177 because he had managed to lodge a big stack of pellets in the barrel. I partially disassembled the gun but couldn't get the pellets out so the gun went into a storage room in my dad's garage.

Now fast forward to about 5 years ago- I was reading airgun stuff on the net and discovered that there was a guy near my home that did repair. I dug out this old airgun at my parents house 150 miles away, then back at home managed to find the box full of remaining parts and put the gun back together. I took it to the repair guy and he knew how to get the pellets out. I put some new finish on the stock where it had a lot of wear, then wrapped it up and gave it back to my brother-in-law at Christmas. He had no clue what was in that long box and was sure surprised to get his old airgun back.

I had a benjamin of my own when I was a teenager, then loaned it to my grandfather to use around his farm. I don't know what happened to it when he died, but my brother-in-law tracked it down, had it repaired, and gave it back to me a couple of years ago.

Here is the gun, the large knob on the rear of the gun is the actuator..

That's a nice looking plinker. Almost looks like an old Winchester 94 –the lever.
These guys
http://bb.bbboy.net/straferbbmachinegunownersgroup
could help you with any questions, I am sure. Its mainly for auto's but the "other" section would bring some help, if you're still looking.

My favorite.....http://makarov.com/drozd/
Bit more exotic, but fun fun. Rat-a-tat-tat

Yeah, it's got a nice very retro look to it. It's lines remind me of a single shot falling block rifle, like a Winchester Low-Wall or something similar.

www.cimarron-firearms.com/LowWall.htm

I'd do some research on this airgun before I would start tinkering with it, or worse, modifying it. If it dates back to 1924, it may well have some collectors value by now.

I understand that using it may have a great deal of sentimental value, but you might just want to consider buying a modern airgun and keeping this one as a display piece.

It really doesn't have much sentimental value..
I was in an attic doing a mouse job for a customer and found it, I knocked a few bucks off my bill in exchange for it.
I like it because it is amazingly accurite.
I will take the advice of not dissasembling it for the sake of making an error..
Thank you for the links guys , I will look into all of them.

Hey, Happy Birthday, Pydpiper! We have the same birthday!

THis might interest you. http://members.aol.com/vintairgun/1923_p2.htm

I had one of those Crosman pump-up pellet rifles when I was a kid. At some point it just kind of stopped shooting with the usual zing. I fould out there was gasket thing in the tube that housed the plunger that went up and down when you pumped it up, and it had basically just worn out. I replaced it and it worked like new. I remember that mine maxxed out on 8 pumps, after that it didn't matter. I think overpumping it can damage that piston gasket thing quicker than normal.

BTW, somewhat OT, but since we're talking about pellet rifles, I've been thinking about buying a new .177 cal spring powered rifle for basic plinking. I dunno anything about these creatures, but notice that there are barrel-break, side-lever, bottom-lever, etc., types of mechanisms for cocking the rifle. Which is the easier to ****, or the best type to get? Thanks....

LMU

Anybody? Any suggestions as far as the type of cocking method?

Mine is a RWS barrel break shoots .177 at around 1000 FPS. I can't help with comparing as I do not have the others. I like mine and have looked at the side lever model but I really do not need two so I never bought it.
Sorry I can't help.
Topper

Topper, what do you think of the cocking action? Is it fairly easy to accomplish?

The valve is not dumping all the air. Does it dump all the air at 4 or 5 pumps?

Cocking tip