Don't Do What I Did!!!

[fisherdude]

I have a Gamo CFX that I am really beginning to like since I did the lube tune.  While I was shooting it last weekend I had this "brilliant" idea.  I pulled back on the cocking lever a little to take the pressure off the breech; then rotated it and put a pellet in it and subsequently pulled back again a little on the cocking lever and closed the breech.  At the time this seemed like a great plan, I could keep a pellet in the firing position and when hunting, I could just cock and shoot without taking the time to put in a pellet because there would already be one there.

Unfortunately, this was not the best idea I ever had.  Apparently when cocking a CFX, the rifle can't get enough air with a pellet in the barrell and the suction formed from pushing back the piston drew some air from around the seal instead to through the barrell.  The result is that a small amount of lubricant got past the main seal and into the high pressure chamber where it "dieseled" for several rounds.  The rifle went "kapow" from a sonic crack for about 5 rounds.  It took me a while to figure out what I had done.

As far as I can tell, nothing was damaged, but I really didn't want to advertise to my neighbors that I was shooting in my yard.  I learned the hard way that, due to the breech design,  keeping a pellet in the barrell of my CFX to save loading time while hunting was a bad idea.

[gamo2hammerli]

Thanks for posting that....I hope other CFX owners will learn from your experience.  Didn't know that some air goes in through the barrel.....

[fisherdude]

When you think about it, when you think about it, the air that fills the compression chamber as you cock the rifle has to come from somewhere, if the barrell is plugged with a pellet, it has to come from somewhere else.  If it has to come in from behind the seal, it will.

[kiwi]

Yer you are right..never thought about it..
 a pellet would block the air from entering..

LOL..I usaly have the oppsite prob ..getting the air out
been known to forget to close the breech..

[hodgjy]

Thanks for posting.  That kind of sharing is what makes this forum awesome.

[RedFeather]

The CFX is a rotary version of the "tap loader".  You have to close the tap in order to draw air into the gun when cocking.  (The tap acts like a ball valve.)  And you don't want to shoot one with the tap in the load position (valve closed), either.

[doc1310]

Good saftey tip. Thanks for sharing.

[Leadhead]

When I first got my CFX, I thought about being able to load a pellet without cocking the spring. Thank God I didn't..........thanks for sharing your experience.

[fisherdude]

A couple of days after I made the original post, it started dieseling again.  There was molly lube coming out around the o-ring breech seal and some was getting in the barrell as well.  It was time to strip her down and start over with the lubes.  

Upon disassembly, there was clearly molly lube in the pressure chamber where it should not have been.  In retrospect, I had put too much  molly  behind the seal and when I cocked with the rifle while the barrell was blocked by a pellet, air came in to fill the chamber from behind the seal instead of from the barrell.  When this happened, a bit of molly came along for the ride.  It was now dieseling when I fired.

Fortunately, there was no damage to the spring or seal that I could ascertain.  Therefore, I just cleaned everything thoroughly and re assembled my baby with new lubes.  This time being careful to only put a film of molly on the seal and not a glob.  So far, it is doing fine once again.

For me, cocking a CFX  while the barrell has a pellet loaded looks like a bad idea.  A certain amount of air has to come from somewhere to fill the pressure chamber and if it can only come from behind the seal, that is what will happen!  If there is lube or oil back there, it will be pulled in as well.

[gamo2hammerli]

Glad there wasn't damage to any parts of your CFX.  Good job in fixing her up.