Tuning 300S kicking my butt!

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1BadDart

1BadDart

Member
May 15, 2017
1,038
207
Kentucky, United States
I bought another 300S, it needs new seals, bumper and a good cleaning. I've got one of the front guide bar pins out but the other one won't budge. I've soaked it in Kroil, heated it with a heat gun, no go. 

I hate to have to cut the guide bar housing to get at the pin as I'm not sure where to find the parts to replace them. I could drill a hole in the receiver on the back side of the pin to get some Kroil on the back side but I don't really want to modify the receiver. 

Ideas?
 
Keeping in mind I have not disassembled my 300s since it just keeps on working, could you grip the pin in front of the sledge with needlenose vise grips, then tap the sledge forward? I would put the second pin back before trying this. It appears the standard technique is to remove the clips then lift the end of the sledge to cause it to bind on the pins, then tap it forward. I assume that is what you have already tried without success. You could also try tapping the pin back in the hope of there being a little play there to allow it to break free. Or possibly heat the pin with a soldering iron causing it to expand, hoping that when it cools and shrinks back it will have broken free.

Other than that you might message joewaynerhea directly and ask him if he has any ideas.

Good luck. Let us know how it works out.
 
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I'm running out of ideas myself, but would it be possible to grind a flat on the protruding end then use vise grips to twist it free? Not much to work with there I know. The last crazy idea would be to clean up the pin and sledge with acetone then glue the two together with epoxy before tapping on the back end of the sledge. If that worked, you would have to unglue the two with heat and acetone to complete the disassembly. On the soldering iron idea, you might have to file the soldering iron tip into a saddle shape to get it to coform to the pin well enough to pump heat into the pin without heating the surrounding areas. The differential heating and cooling is what is supposed to loosen the joint.

On the grinding, if I were to do it I would fixture the receiver in my mill and use a cup wheel to grind the flat. It would be pretty hard to do a decent job free hand with a Dremel.

After reading this I hope I never have to take mine apart!
 
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I finally got it, heat, spray with Kroil, rinse and repeat. Even after it started moving it didn't want to come out easy.



The culprit.

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Congratulations! Glad it worked out.

A question for you: How were you able to tell the buffer was shot before opening it up? Is there some way to check its condition without disassembly? My rifle continues to chronograph around 640 fps, so I assume everything is still OK in there.
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It sounds like your gun is very healthy, mine are in the 560fps range with 8.02gr pellets.



When you cock the rifle look through hole in the breech seal and you can see the buffer. All three of mine had cream colored buffers which as I understand is the color they came with from the factory. If you start seeing chunks in the bore or chamber it's time to change it.
 
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The reason I took it apart.

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I had the same experience. Very frustrating. Had to use the soldering iron and liquid wrench. Had to be careful not to start a fire! Tapped on the offending pin and used vice grip pliers and a hammer to hit the pliers. Finally got it moving but like you said it didn't come out easily. I finally almost had it out and got impatient and then I broke the pin. I was able to get a new one from Neal Stepp at International shooters service. I documented my journey with the FWB 300 in this post "Getting My FWB 300 Shooting Again" along with photos.
 
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Make sure to read THIS then if all we done properly and still 550fps with 8gr...

https://www.gatewaytoairguns.org/GTA/index.php?topic=168115.0

Try removing the breech seal and stick a faucet washer in its place and chrony it. It should contour itself regardless which way the cone washer is seated. Last ditch effort to check to see if you really need to replace the spring or not.

Unconventional yes. But I may know a thing or 2.
 
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