GBB Firing Issue?
 

Hey guys,

I just bought a second-hand GBB and it appears to have some issues firing. The problem is the first BB comes out nice and hard but after that they either roll out or don't come out. It does have a tightbore installed and when I put a BB into the chamber it takes some force to push it through. What could be causing this? It's a KSC USP .45. The nozzle is a little loose but the screw is stripped so it can't get any tighter. I don't think that's the problem though as when its in the gun there's no room for it to move anyways.

What kind of BB's, what kind of tightbore, size, etc? Hopup on/off? Anything else?

I've tried BBQ BBs (from a local guy) and KSC Perfect 0.20s. Hopup has been tried at all settings (currently set in the middle). Tightbore is a 6.03 or 6.04 I believe.

There's 150% recoil and trigger springs.

EDIT: Also, there's still a decent amount of kick to the pistol (enough to lock the slide back).

How are you chambering the first BB?

If the hopup isn't on far enough the 150% recoil spring might be forcing the BB past the hopup, hence the rolling out of the barrel.

I have a Guarder metal slide and a 150% recoil spring (really snappy) and I have to keep the hopup at >50% to keep BB's from rolling out the end of the barrel when they chamber.

Maybe that's the problem? Although you said you tried all settings....hmm.

They're not rolling out after being chambered. They're rolling out after I fire. The first one is nice and hard but after that they roll out or sometimes don't even make it out.

Ah. Different problem then. Tried lubing the hopup? Or reseating it?

Lube improved things. Maybe every second shot coming out now at best. How do I reseat the hopup?

I meant take the barrel/hopup assembly apart and put it back together. Maybe something went wrong.

Just an update:

The first round fires fine but the rest aren't again. What's actually happening now is the first round it firing and the second round is dribbling out right after being chambered, even with the hopup at 100%. It looks like the hopup rubber is actually coming out now so I'll take it apart after school and try to "reseat" it.

Ive had this problem happen so many times before with my KSC USP .45 and compact.

The problem is that there is too much oil on the hop-up, which causes the nozzle to push the BB's past the hop-up because there is not enough friction. What I do is take a shot the clean the hop-up with a q-tip and then take another few shot then clean the hop-up again. If the hop-up looks like its coming out it's probably because its swollen from too much oil. What you need to do is take it out and try to dry it. ( you might need to get a new hop-up)

This happens to me allot right after I clean and re-oil them. I think KSC USP's have a really touchy hop-up.

Hope this woks your you.

This may be a little risky so see what others think of it before you do it. It sounds like your loading nozzle is pushing the bb past the hop-up. Try to file your nozzle down a bit. Just like a mm or something.