M77 Light Primer Strikes?

B

Bullet Bill

Inactive
I have a Ruger Gunsite Scout which is based off the M77 action and never had any issue with it until the last time out.

It fired all of my reloads with Federal 215M primers but when I switched to factory Aguila 7.62x51 ammo I had 3 misfires in a row. All of the indentations on the Aguila primers seemed really shallow. The gun doesn't seem to snap as loud as I remember when the trigger is pulled but I could be imagining things. Anyways I thoroughly inspected the spring and can't find any breaks in it nor can I find the firing pin hanging up on anything. Everything is clean and well lubed.

Has anyone else had an issue with this? Are Aguila primers ridiculously hard? I know the Federal primers are notoriously weak. Seems kind of odd for a bolt action to be having light primer strikes, never had an issue before with other brands of NATO ammo.

EDIT: The rifle does have over 3,000 rounds through it, could that just be the end of its firing pin spring life? I never store it cocked.
 
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Harder primer cups?

Does the firing pin stick out of the bolt face at least. .055 inch?

We're the cases too short in head to shoulder length; too much head clearance?
 
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The firing pin protrusion seems good. Possible that the cartridges had too much clearance, I don't have a case gauge to compare, there was no resistance closing the bolt.
 
My M77 MkII has about 800 rounds through it and is exhibiting symptoms of a weak striker spring. I ordered a new one (24# instead of factory 21#) last week.
 
Nah, not enough to care about. IIRC the brand I installed was a "Blitz"- but I could be wrong- it was in 1988.

It never did this with non-surplus ammo, and would work with my surplus ammo if the weather was warm, but combine cold conditions like 20 F and below and it would. It wasn't gunked up factory lube either, as I had done the usual degrease-the-bolt-and-mainspring thing first.

The ammo I had issues with was Canadian MG ammo headstamped DA-62. I used to get it for about $5.00 a hundred back in the 80's.
 
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