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Old 08-19-2012, 01:32 AM   #21 (permalink)
Tuning up the armory
Folken's Avatar
Join Date: Jan 2011
Location: New Brunswick, Canada

Originally Posted by Blender View Post
Hmm. I work on STBB's all the time. Here's some stuff to do.

First, order a new spring guide, or borrow one from another marker. They sell for a few dollars on eBay. This part is quite necessary. If need be, you could probably make one from a dowel, delrin rod, round headed bolt, or something similar. Also, order a new striker o-ring. Rumor has it it's a 016. Buna should work fine. These can be bought on eBay (look for "spyder fat striker o-ring") or on McMaster-Carr.

When your parts arrive...

Remove the grip frame from the marker, and remove the back caps, main spring, striker, and bolt.

Clean the bolt and striker off, and clean inside the body. There should be no residue on any of these surfaces.

Replace the striker o-ring.

Check the hammer and sear for wear again. The edges where they interact should be sharp, and not rounded off at all.

Check the sear spring, make sure it's working and strong enough to pop the sear back up in time to catch the striker. If you have another STBB to compare it to, do so. (I would suspect this would result in bursts rather than sustained burping)

Check/Replace any o-rings on the bolt. As far as I know, they should be a 015. I think a tank o-ring would work for this.

Lubricate lightly with some sort of oil -- no grease or "lube", and nothing aerosol. Tippmann recommends Hoppes #9, Brass Eagle used to suggest mineral oil. Air tool oil and automatic transmission fluid have also been used with fine results.

Reassemble according to your assembly diagram, making sure the grip frame screws are quite tight.

Screw the velocity adjuster halfway in and see if the marker works at that point.

Hopefully that helps...
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.

Originally Posted by tjd10684 View Post
I am pretty sure the oring you need is a 016 size with a drometer of 90. If you were not in Canada I would suggest buying a box from mcmaster but you should be able to find what your looking for somewhere in the great white north.
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?
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