Home Forums Hunting & Shooting Gunsmithing Ruger m77 bolt firing pin spring

I have a M77 257 Ackley Tang safety Ruger that when you pull the trigger the firing pin action works but is not a strong enough strike.
I compared it to my 338 and my 30-06 both have a nice snap. The 257 is roughly half.
I took it apart and cleaned it but still not good.
I looked in brownells and he does not have a new spring for it right now, any body have a good idea were to purchase one. I would even look at a hole new bolt if it was a decent price.

I think There is a Tubbs speedlock made for the 77s

I find it hard to believe the spring "got weak" on it. If the firing pin screws into the striker it probably became partially unscrewed during use. This relieves some of the pressure on the striker spring and reduces the amount of firing pin tavel, thus reducing the firing pin striking force. I have experienced this problem on another rifle. I removed the striker from my M77 and looked at it but cannot tell if the firing pin is threaded into the striker or pinned. Try to turn yours. If it will turn then it is threaded and has come partially unscrewed, causing the problem as described. DON'T turn it CCW without holding it with firm pressure with the firing pin pressed into a 2x4.

If the firing pin is screwed into the striker and it is partially unscrewed then you will have to tighten it. I suggest first removing the firing pin from the striker, degreasing both threads, and applying a thread locking compound before tightening it in place. This is how I fixed the same problem with my Weatherby. As I said, you want to contain the striker and firing pin before disassembling the unit due to the high spring tension. I would stand up, put a 2x4 on a solid table, and press firmly on the back of the striker with the heel of my hand with the 2x4 under the point of the firing pin. Then unscrew it with the free hand with a pair of pliers on the front shoulder of the firing pin. Apply a double layer of duct tape inside the jaws of the pliers beforehand so you don't bugger up the firing pin. When it comes unscrewed you can release the spring tension slowly and remove the firing pin. Clean and degrease the threads, apply a permanent thread locker, and reassemble it. Let the threadlocker cure before installing the bolt into the rifle and trying it.

I hope this helps you.
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I bought a Ruger MkII 77 in 7.62x39 about 1990 or so. Using surplus military ball I was getting an occasional failure to fire because of harder military primers I imagine. I did not have any problems with commercial US ammo or my own reloads.

At any rate I bought a Wolff Blitz mainspring that upgraded the issue spring by a bit and the rifle has shot fine ever since with any ammo I have tried including the original surplus that had the problems.

The firing pin is pinned to the striker and the Rem/Ruger bolt disassembly tool from Brownells is a good tool to have for disassembly of either bolt. I haven't checked the Brownells catalog but would think Wolff still offers Ruger mainsprings. Plateau Hunter

Just bought a Wolff spring from Brownells last week, and it looks like they still have them. Now, just have to figure out how to install it. Might have to look into that tool.

My spring was like $10, and came with a reduced weight trigger spring too for the MKII models.

Anyone know what the factory firing pin spring weight is? The Wolff says 24 pounds.

I had the same problem with a used M77 MKII that I bought than rebarreled in .35 Whelen (never shot the donor). I was getting misfire with factory and reloads. Headspace was fine, tried fireformed brass but was still getting regular misfire. I finnaly bought a Tubbs Speedlock and never had a misfire since. The Tubbs spring is supposed to be factory weight and was way stiffer and longer that the factory spring it replaced.

Thanks guys for the ideas. Big_Redhead I think you might have nailed it. I took the bolt apart from 06 and the spring looks different than the 257 I do think the 257 has become unscrewed.
Will go tonight and get some thread tight and try the method you laid out.
BCSteve I do like the the Tubbs Speedlock idea though.

The cocking piece in the M77 is pinned to the striker, and is a PITA to get off/replace unless you know how. The easiest way is to make a sleeve that is .55" long and 3/8" in diameter. Drill a hole through the middle big enough for the point of the striker so the sleeve will slip all the way back to the flange.

Remove the striker from the bolt. Drop the sleeve into the bolt. Screw the striker back in and screw down far enough to drive out the now-exposed cross pin. Ease the cocking piece back out of the bolt, being sure to control it when the threads disengage and everything is free to fly across the room. Reassemble in reverse order.