Well, I’ve had it in bits and given it a clean, deburred the slot, fettled the ears, fettled the spring ends, made a spring sleeve. Now regressed and reassembled.

It already had the synthetic guide inset into the cocking arm from the factory, so happy days.

No sign of damage anywhere, I’m wondering if the noise I was hearing was just the guide ribbing along the cylinder bottom or maybe the ears inside the slot. Anyway it sounds smooth enough now.

Even then twang has gone after fitting the spring sleeve.

Shot a few through it and it seems fine.

Fingers crossed it stays that way.

Thanks for the input chaps.