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Old 08-19-2012, 07:19 PM   #24 (permalink)
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Join Date: Feb 2007
Location: Laramie, WY/ Duluth, MN

Originally Posted by Folken View Post
I was able to get a new spring guide and a flat disk and it didn't help. The inside of the gun is clean and oiled and has all new springs and o-rings except for the fat striker o-ring. But now that I have the proper dimensions for the o-ring, I should be able to buy what I need at my local automotive store or someplace like McMaster-Carr.

The sear and hammer are still in good shape with sharp edges. Also, adjusting the velocity all the way up and all the way down did not help. Will have to try a new sear spring if I can find one.

Something to note is that the bolt is aftermarket and has no o-rings at all. Does that matter? There is a picture of it a few posts back. It's red.

Thanks! These measurements will be extremely helpful. Now I can try tracking down a replacement. Should the striker o-ring be buna, urethane, polyurethane, hard polyurethane?
The sear spring is an unlikely issue, but possible. As I stated, it's more likely that the marker would just fire twice.

Provided that the bolt is for the correct marker, it's unlikely to be an issue. It is pretty worn though -- try using some fine steel wool, 800 to 2000 grit sandpaper, or something like Mother's Mag polish to clean that up.

I can almost guarantee that this is the o-ring, however-- I own about 15 STBB's and that striker o-ring is the only thing I've ever had a problem with.

Also, a video of this thing attempting to shoot would be fantastic. You can tell a lot by how it cycles. In fact, it's important for us to know if it's "burping" or "jackhammering". Burping is a pressure or seal problem, jackhammering is a hammer/sear problem. Burping is the typical "out of air" sound and stops after a second or so, and jackhammering is violent, uncontrolled full-auto that doesn't stop unless you grab the cocking knob.
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