Air Gun Home :: View topic - P17 Issue

Bean · Veteran Member

I know the P17's are prone to worn o-rings after some time. This pistol is 2 weeks and ~ 5-600 shots old, already getting an air leak occasionally. I lubed it - good for now. I'll worry about it when it gets worse.

New development today. 4 times within 30 shots, a full pull on the trigger did not fire the gun. Yes the safety was off, can't move the trigger with it on.

Squeezing it harder did not fire it, I had to pull it sharply while aiming into the ground to fire it.

Have I missed complaints on this or is this really a odd problem? I have no problem going for a replacement but if this is common I'm not sure I want another one....

Bean

edit... just realized i post this in the wrong forum, sorry. Also, because I'm annoyed - I've kept shotting to see what happens - this is happening every two or three shots now. Goin' back...

cw · Banned

Mine did the same thing when I first got it. Lubricating the trigger group
cured the problem. good luck with it and have fun, they're a great pistol.

Slavia · Moderator

No such problem with mine. Lubrication sounds like a good idea.

Seriously consider chamfering or de-burring the air inlet hole on the side of the cylinder. This will eliminate piston seal damage. On the plus side, I got all my seals ("o" rings) at an automotive parts store, and they're not hard to change.

cw · Banned

Hey Bean,

I just seviced a P17 that had the same problem because
of a loose valve stem nut. see photo. try tightening it and see if
your problem goes away.

Bean · Veteran Member

Thanks cw !!
Thats great info - I need the visuals.

Since I was having this issue on a 2 week old gun, I sent it back for a replacement. Unfortunately, the replacement is developing an air leak after only ~ 150 shots. I'm tempted to keep this one as the trigger is much crisper and it seems to a little more consistent but I'd need to learn how to do the seals/o rings myself.

If you have any pointers/pictures/links to write ups on the o-rings and the right pieces to pollish to avoid repeat issues, I'd be in your debt.

Bean

cw · Banned

You need to chamfer the air intake port. The piston o-ring slides
past the intake port at the end of the cocking stroke.
This is what causes the hiss you hear at the end of the cocking stroke
if you hold your ear next to the gun. If the port edge is sharp and not
chamfered (beveled), a small chunk of o-ring will be torn out each
time the gun is cocked. I will be able to post photos tomorrow, if it
will help.

Bean · Veteran Member

Pics would help tremendously. I'm not affraid to take things apart, but taking the right things apart and getting them back together has always been my issue. I'm an offroader - I'm used to working on much larger parts - like Jeep suspensions. And even then..... I'm not always succesful.

If you're willing, what I'm really looking for is 'how' to get to the o rings etc. And then a pic of the area to work on, but I think I can picture that in my head... crap maybe I should just send you the gun.

...edit for stupid typing (at least what I noticed)

Slavia · Moderator

It's not difficult:

Loosen the setscrew at the end of the piston. It only has to be loose; it does not have to come out.

Push the pin out. The piston can now be pulled out of the cylinder. The piston seal is an "O" ring at the head of the piston, much like a ring on an automobile piston. When they drilled the air inlet hole, they probably left burrs that are tearing the seal. This was true for both CW's P17 and my Marksman 2004.

I teased out the burr with a pocket knife, and then smoothed the area with fine emery cloth. Clean everything well with a clean cloth. (Don't use solvents that can migrate into the valve body and cause seal degredation inside.) CW will probably have a more elegant way to chamfer that hole.

I got my "O" ring at an automotive parts store. Just bring in the old one and get the same size. Put a very thin coating of lubricant on the inside of the cylinder before assembly. I use a synthetic grease; I belive CW uses moly.

Bean · Veteran Member

You guys are fantastic. Thank you very much.

cw · Banned

I use a mini die grinder (Dremel or like) with a ball diamond bit.

A fine silicon carbide grindstone will also work, but you will need to
take some 600 or finer emery paper or cloth to the ground area
afterward.

While your in there take a 2mm hex key (allen wrench) and make sure
that the cylinder pivot pin set screw is tight, or the pin might walk during
cocking.