frusration...breech o ring25.bobcat

Jump to latest Follow Reply
wrong size is wrong size... The ones you found will have a larger OD than what is spec'd, which will make it difficult to get in, and once in, the probe will want to push it out.

I have not tried replacing the O-ring on my Bobcat yet, but have installed MANY o-rings on my own builds, which are configured the same way as the FX. The first few times it may be easier to push a pellet into the bore to block it off, so the o-ring will have no where to go, other than the groove. If you pinch the o-ring side to side, they will generally take on a curl. I insert the curl into the groove as much as possible, and then use a small allen key(or pick) to work the rest of the o-ring into the bore, and groove. First few times is a PIA, but you will get the hang of it and it will become second nature...
 
Upvote 0
GUIDE TO REPLACING A BREACH O-RING:

Tools Required:
  • O-ring Pick *
  • Silicone Grease
  • .25 Pellet
  • Dowel Rod or Cleaning Rod (should have a diameter slightly smaller than the bore diameter).
Parts Required:
  • Metric 6.35mm x 1.27mm Buna-N A70 O-ring
* O-ring picks and silicone grease are typically carried by scuba dive stores. The best pick I have found is available for less than $4 (see resources at end) A plastic cocktail skewer or safety pin can be used in lieu of a brass pick. However, you risk injuring yourself and possibly your rifle. Seriously, get yourself a set of $10 brass picks and be done with it.

Step-by-Step O-Ring Replacement:
  1. Insert a long rod down the barrel through the muzzle to the point where the end of the rod can be seen just inside the breach behind the breach O-ring. The rod keeps the new O-ring from getting pushed or slipping down the barrel which is a royal pain to get out
  2. Using the pick, gently wedge the tip of the pick under a section of the O-ring between the channel holding the O-ring and the O-ring itself. This will lift a section of the O-ring up which will allow you to pry the rest of the O-ring free from its channel. Remove the old O-ring and discard.
  3. Take a new O-ring and smear silicone grease all over it. Work the greased O-ring between your fingers so the silicone can spread all over it.
  4. This is the tricky bit. Take the new O-ring and pinch it between thumb and forefinger and gently place insert into the breach. It may need to be nudged into place. Once in place, it should be sitting just behind the pellet skirt just inside the breach.
  5. Using the tip of the O-ring pick, start prodding a portion of the O-ring into the groove of the channel that holds the O-ring in place. The approach is to seat a small section bit by bit working your way around. The method is quite similar to replacing and inner tube on a bicycle wheel.
  6. Once the O-ring is completely seated in its channel, gently push the pellet probe forward to make sure it clears the newly installed O-ring. Do this a couple of times. If you wish, you can use the tip of a cotton swab to clean any spare silicone grease present inside the breach or on the pellet probe.
    [/LIST=1]
    Regards,
    Scott

    RESOURCES:

    6" miniature push/pull hook pic ($3.93 from McMaster-Carr): http://www.mcmaster.com/#7426a32/=wxb27w
    • ?ver=1291967231
 
Upvote 0
Thanks for posting that Scott! And, Thanks for starting this thread JAM! I was going to start a new topic on this very thing as soon as I got my o-rings in the mail. I've heard that this can be a difficult procedure and this will be my first time. 
I wonder... Is there any benefit in replacing o-ring on a schedule? Say, every #### of pellets or # of years?
 
Upvote 0
You must log in or register to reply here.
Top Bottom
Back
Home
Forums
Resources
Menu