I'm right on the verge of purchasing a Diana 350 Mag in 177. I had owned one a few months back and it was real noisy when cocking! Sounded really dry. I kept shooting it after reading that spring guns need broken in, but the screaking sounds didn't seem to be quietening. So I got rid of it. Now I want to try it again, and maybe give it a better try. Is there any way of getting some lube on the sping withouttaking it apart? Maybe a shot of teflon spray through the cocking slot or something? Or is tear-down necessary??? Thanks. Kevin
A proper tear down and lube with moly is the best bet. The new ones are coming pretty dry from the factory. You might try removing the action from the stock and use a Q-tip to get some moly behind the piston. Re-assemble and cock a few times to work it in.
I have two 350Mags and they both shared a common problem:
There is a metal wheel in the cocking linkage that contacts the receiver during the cocking stroke that appears as if it's designed to roll along the receiver tube. However, the ends of the linkage through which the wheel's axle is held are a bit too narrow to allow the wheel to turn. I've repaired both of mine and they are very smooth and easy to cock (and don't gall the receiver tube). It's an easy fix, but you do have to remove the action from the stock as well as carefully remove the cocking lever shoe from inside the receiver tube. There is a metal sleeve around the piston spring that is easily bent if you're not careful.
FWIW, I learned about this from a reputable tuner that told me that every 350 he'd seen had the same issue.
I also agree that some proper lubes would help, too.