ULT causes minor bolt stick?

[Justus]

Since I tuned my level 10 on my X valve and shaved the on/off pin down to make it more reactive, I haven't had any problems with it really. I wanted a lighter trigger pull, though, and more reactivity like I got with Ochsy's shimmed-up ULT, so I got a ULT kit last week.

I put all but 2 shims in it (6 shims total I think) and went to town. I did get the reactivity I was looking for and a very light pull. However, when dry firing through a tank of air to test everything out, there were several times I got some bolt stick, and had to push the tip of the bolt back very slightly to hear a click before it would reset and fire again. Would just adding the ULT cause that? How do I go about diagnosing the problem now, when I had completely gotten rid of it before?

[athomas]

If the ULT is timed right on the edge of operation, shifting of the orings could on occasion allow a burst of air into the chamber before the bolt is reset. This could cause bolt stick. You can correct this by removing a shim. However, if the on-off is sealed after the initial air leak, the bolt should still reset on its own. If not, this is usually a carrier size issue that has just shown up because of the ULT installation and the fact that it has less tolerance for errors.

[Justus]

I took a shim out (had 5 in, down to 4 now) and lost the bolt stick as far as I can tell. The RT effect has, understandably, gone down quite a bit, but I think that's okay with the extremely light trigger pull. Now I just need to watch out for short stroking.

[athomas]

Make sure the shim you took out was a ULT shim and not a level 10 shim. The level 10 shim is equivalent to 2 ULT shims.

[Justus]

It was extremely thin. I had my Level 10 tuned before purchasing the ULT kit new, and made sure to not mix the parts. I did notice the ULT shims are less than paper thin - one was slightly warped right out of the kit (I didn't use that one).