I have the same gun in stainless. Had the same problem & it cost me a 2nd shot at a dandy buck. I sucked on the first shot. Here's what I think the problem might be:
There is a lot of corrosion potential in the bolt mechanism. You have to clean the bolt a lot. I clean mine every time I shoot. You clean yours a lot?
I think the corrosion erodes the spring until it doesn't have enough tension. I'm switching to a stainless spring. I have some around here & I'll check to see if they fit. If they do, I can send you one.
The steel springs they provide with the gun aren't stainless, and they might hold up better if they were.
The biggest gripe I've had with the gun has been the safety mechanism. Not too safe in the brush. I can't switch to a left shoulder carry, because the safety snags on my belt and flips to fire.
Nice and light to carry, though. The look cool, too. But looks aint everything!