Peter, thanks for your clarification.
I understand your concerns, especially since you don't live in the US (so acquisition and repair is already a hassle - sounds like you're in Belgium, or at least western Europe) and that you seem to appreciate fine guns - your 39 is going to live in good company with the Anschutz around
- but good that you've had good experience with your 336 and understand it. That's going to make a solution easier.
I may not be the one to offer solutions to your issue, but there are others here far more knowledgeable about the 39's than me. (I just started this club so I could learn from them.
So, to make sure we all understand the problem, a couple of more questions for you, please.
Please pardon the simplicity of my questions, but we should start with basics.
instead of the hammer slamming on the firing pin, it just gets stuck in the half-cocked position
OK, clearly this can't be as simple as the cross-bolt safety being on, right? I'm asking because if your 336 is a pre-safety, you may have overlooked the one on the 39a. Unlikely to be sure, but better to check.
Other than that, I confess I can't understand why the hammer would stick. What could it be sticking on? I'm not doubting that it is, just trying to parse what's doing it.
Does it do that every time you pull trigger (by the way, don't dry fire it), or just sometimes? If the latter, how often? What proportion of shots?
And when it gets stuck on half-cock, what happens if you pull the hammer back and fire again? Same thing?
Any thing you can do to help us visualize this issue will help us offer suggestions. Be as detailed in your description as possible, and we'll understand that English
may be your second language. (Even though the reason I'm having trouble understanding your problem is due to not enough info yet, not your use of the language.)
Nem