.25 cal Bobcat, new out of the box Chrono Test shows average Hi Power at 930 fps and average low power at 665 after 22 shots. Gun started sounding differently recently and every shot results in a puff of air on my cheek. Choro'd a couple shots today and hi power is now 910 fps and low power is 650 fps. The breech seal is difficult to see even with a light and magnifying glass. Anybody with more experience have suggestions?
FX MkII Bobcat Breech Seal Damaged?
- Thread starter beercanshot
- Start date
Breech seals are sort of a routine maintenance item...just change it and then there are no worries. Have extra on hand as you never know when you might blow one out.
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I would hope it has not gone bad already......that gun can't be very old! Please let us know what you find. That way I know what to order and have on hand for my MKII LOL
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Lots of experience having owned a Bobcat. The breach o-ring is easy to replace with the proper tools and technique. They can also fail at anytime, regardless of how fresh they are. You can keep o-rings supple by applying a little silicone using the tip of a cotton swab. I posted this back on April 26th:
GUIDE TO REPLACING A BREACH O-RING:
Tools Required:
GUIDE TO REPLACING A BREACH O-RING:
Tools Required:
- O-ring Pick (In a pinch, a plastic cocktail skewer or safety pin can be used in lieu of an o-ring pick)
- Silicone Grease
- .25 Pellet
- Dowel Rod or Cleaning Rod (should have a diameter slightly smaller than the bore diameter).
- Metric 6.35mm x 1.27mm Buna-N A70 O-ring
- 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
- 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.
- 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.
- 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.
- 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.
- 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.
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Regards,
Scott
The best tool I have found is a $3 miniature push/pull hook pick from McMaster-Carr shown below.
http://www.mcmaster.com/#7426a32/=wxb27w
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The .25 Bobcat uses a Metric 6.35mm X 1.27mm A70 Buna-N O-ring which is not a common size in the States. However, I found a couple of places the sell them:
- Maryland Metrics (http://mdmetric.com/or/gb01.htm) THIS IS AN AWESOME PLACE FOR RARE TOOLS AND PARTS FROM EUROPE. I RECOMMEND YOU TRY HERE FIRST.
- Metric Seals Inc. (https://metricsealsinc.com/store/BS803_V80_BLACK/i_0_0_84/_6.35%20X%201.78%20V80%20BLACK.aspx).
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The power adjuster can also cause a puff during fiering. Sometimes you can just turn it a few turns and the puff is gone.
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I had a same problem with my BobCat MkII in .22 cal. It came up after about 2000-3000 shots. Does anyone know the exact size of the breech o ring in .22 cal?
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The oring store out of california. I got 50 1.5X5mm buna-N70 orings for 2.50 cents. Not sure what standard shipping is because I overnighted mine due to being impatient. That was for my wolverine .22. Just make sure you order plenty to have on hand.......its very irritating having a 5 cent oring putting your shooting on hold.....Ive been there as probably most everyone else.
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