Soo.. issue: Fires on action release

[4 Scale]

Originally Posted by Rich T

Pin is retracted.

But something is hitting the primer, at least when the breech closes. Is there a mark on the primer (I would think there must be) and does it match the firing pin tip?

If the firing pin is setting off the primer when the breech closes, then at least part of the problem is failure of the FP to reset. Testing with snap caps should confirm if the FP is reseting or not.

As an example of a reset issue, I once installed a new side plate and trigger lever and found the firing pin would not reset. The culprit was the trigger level was new, and did not have the correct bevel to engage the plunger properly. Filing a bevel on the trigger lever fixed the issue. My point is, you'll have to carefully investigate if the FP is resetting.