Leaking down the barrel revisited

[Severe]

I've been dealing with a recurring slight leak down the barrel on my .68 classic for about a year now. When ever it rears it's ugly head, I tend to replace the o-rings in my On/Off and check the carrier on my level 10. However, this time out, the little bugger still persists to leak. This one of those leaks where if you ever so slightly rest your finger on the trigger, it stops. Sometimes after a string of shots it's fine, other times it's venting pretty good.

One possible problem that has been mentioned is the wear on the sear. Considering the marker probably has well over 200 cases shot through it, that's a distinct possibility. I'm not opposed to buying a new sear and all but I have been considering a different fix but wanted to run it by the jury at large.

If I understand this type of 'sear' leak correctly, the wear on the sear allows the bolt to drift forward just a little. Enough that the o-ring on the carrier is now over first stage venting hole causing the leak. If that's true would it be possible to somehow move the carrier further UP the power tube? Maybe by putting shims between the carrier and the white plastic washer? Or perhaps another location. If that doesn't work, could possibly sanding the top of the carrier down to allow it to sit closer to the power-tube tip help?

Is there another fix I'm missing aside from buying a new sear?

Thanks,

[Tunaman]

I've been dealing with a recurring slight leak down the barrel on my .68 classic for about a year now. When ever it rears it's ugly head, I tend to replace the o-rings in my On/Off and check the carrier on my level 10. However, this time out, the little bugger still persists to leak. This one of those leaks where if you ever so slightly rest your finger on the trigger, it stops. Sometimes after a string of shots it's fine, other times it's venting pretty good.

One possible problem that has been mentioned is the wear on the sear. Considering the marker probably has well over 200 cases shot through it, that's a distinct possibility. I'm not opposed to buying a new sear and all but I have been considering a different fix but wanted to run it by the jury at large.

If I understand this type of 'sear' leak correctly, the wear on the sear allows the bolt to drift forward just a little. Enough that the o-ring on the carrier is now over first stage venting hole causing the leak. If that's true would it be possible to somehow move the carrier further UP the power tube? Maybe by putting shims between the carrier and the white plastic washer? Or perhaps another location. If that doesn't work, could possibly sanding the top of the carrier down to allow it to sit closer to the power-tube tip help?

Is there another fix I'm missing aside from buying a new sear?

Thanks,

I dont understand. If you think you need a new sear, just get out a magnifying glass and take a look at it. 200 cases and I say it may be time. I would be happy to tell you exactly what is wrong with it if you would like to send it to me. My guess is that a complete overhaul would do you good for another 200 cases. Let me know.

[Dayspring]

Well, you could try and remove any shims you have in the powertube. What's your level 10 setup?

[Severe]

Thanks Tunaman, I'll keep that in mind, but I'm thinking it's a pretty easy fix in the scheme of things. New sears aren't terribly expensive and I have several Classic Parts Kits lying around.

DaySpring, my level 10 config is 1.0 carrier, no shims, short spring. If I go to the .5 carrier I get bolt stick. I probably should have mentioned that from the get-go.

In looking at the tip of the sear that catches the bolt, it's slightly polished. Again, potential indication that the sear needs retiring. Also, I'm noticing some slight buffing/polishing action on the carrier on each tip indicating that the carrier may be rocking back and forth during the firing sequence. That kind of makes sense since the o-ring on the carrier is going to act as a pivot point and with enough friction it's bound to move around some.

In thinking about solving this without buying a new sear, I was trying to imagine how the carrier sits in the power tube. Does it remain flush against the back of the power tube or does the air pressure push it up against the power-tube tip. I'm pretty sure it's the latter since the shims are put between the carrier and the power-tube tip. If that's the case, light sanding of the carrier 'should' provide a quick painless fix.

Has anyone ever done this to solve this sort of thing?