Problem with No. 4 Mk1* Trigger

[Maple_Leaf_Eh]

Does the rifle have its bedding screw collar? That is supposed to keep the front end solid between the trigger guard and the receiver, and then the trigger can be tested as issued. I suspect you need to swap in a few parts to find what's not working. Ypur problem is the back end. Have you considered that the trigger guard itself is bent? Maybe you should experiment with that.

Once my unit was on a machine gun shoot and my 7.62 C1 MG (M1919A4) wouldn't fire. The trigger would not release the sear on the bolt. I was horrified to see the weapons technician strip out the trigger bar, feed it into the barrel jacket holes and give it a strategic bend. Reassemble and resume firing. And I thought all along that there were guages and new parts in plastic baggies or bins to fix things. He shattered my exalted opinion of gun plumbers!