Adjusting Savage Firing Spring Tension

[SingleSeven]

How do I set the firing pin tension to between 20 and 25 lbs on a Savage 12 LRP? I took the firing pin assembly apart to readjust protrusion after bolt work, but I'm not sure how tightly to screw on the bottom firing pin spring retainer for proper cocking pressure. Is there a way to measure tension on the assembly or by feel somehow?

 

[boltfluter]

A bathroom scale may work.

Paul

 

[NorCalMikie]

And you want to check/change the tension for what reason?
If it ain't broke, don't fix it!!

 

[SingleSeven]

I don't think a scale would work because the spring is captive between the two threaded endcaps of the assembly (it doesn't slide).

I think I need a primer on how the bolt cocks the firing pin. The spring is help captive on a rod that's threaded on both ends. The top end piece (closest to the firing pin) sets the depth of protrusion for the firing pin. The bottom end piece, as far as I can tell, either compresses the spring if turned clockwise or decompresses the spring if turned counterclockwise. I don't understand the purpose of the spring in this configuration or by what mechanism the firing pin is propelled into the primer when the trigger is pressed because the firing pin assembly is free floating in the bolt body except for where the cam pin is attached. I'm guessing the bolt created torsional pressure on the spring when rotated, but I'm not sure how that makes the firing pin move forward when the trigger is pressed. I've looked for online tutorials but have come up empty.

 

[SingleSeven]

I want to set tension correctly because I had to disassemble the end caps releasing pressure on the spring to set firing pin protrusion. Before that, I was experiencing pierced primers with moderate loads and thought the firing pin pressure might have been excessive.

 

[olddav]

You may find a knowledgeable person over on Savage Shooters forum. I believe they can guide you in the right direction.
One thing to note is that compressing the spring may/will alter firing pin travel, but I could be wrong as I often am.

 

[NorCalMikie]

And you want to check/change the tension for what reason?

I have 5 Savage rigs. Had the bolts and firing pins apart many times with no issues. Never saw a reason to check the tension.

Before that, I was experiencing pierced primers with moderate loads and thought the firing pin pressure might have been excessive.

I think you may be looking in the wrong place?
From my experience, pierced primers are usually from loose brass in the chamber. (headspace) NOT a chamber problem, brass issue.
Firing pin pushed case forward in the chamber, round goes BANG and has rearward movement, primer tries to back out of the pocket and gets punched. (pierced)
Fired brass formed to the chamber will correct that problem but make sure you don't push the shoulders back too far and get the same thing all over again.
And NO, the firing pin doesn't need to be bushed either.

 

[olddav]

If you want to ck the spring install the “cocking piece sleeve”. Stand the firing pin on a scale (pin side up), straddle the firing pin with a tool, perhaps some wire strippers and compress.

 

[Dgd6mm]

I have to ask, what cartridge is this firing pin for and what brand primer(s) are you piercing??

 

[SingleSeven]

I have 5 Savage rigs. Had the bolts and firing pins apart many times with no issues. Never saw a reason to check the tension.

I think you may be looking in the wrong place?
From my experience, pierced primers are usually from loose brass in the chamber. (headspace) NOT a chamber problem, brass issue.
Firing pin pushed case forward in the chamber, round goes BANG and has rearward movement, primer tries to back out of the pocket and gets punched. (pierced)
Fired brass formed to the chamber will correct that problem but make sure you don't push the shoulders back too far and get the same thing all over again.
And NO, the firing pin doesn't need to be bushed either.

Interesting. If I screw the bottom retainer in as far as it will let me (no space between spring rungs), then the bolt becomes very difficult to lift/cock, but if I only turn in the bottom retainer one or two revolutions then bolt lift becomes frighteningly easy, which is worrying me that it may be insufficient to ignite the primer. How may turns do you usually tighten the bottom retainer on your Savage bolt assemblies? The spring is stock Savage.

I started off with new Lapua brass, but have since reloaded the same brass twice more and am still getting pierced primers (some) with moderate loads. On the first go I was seeing slight ejector marks on the brass, but since reducing powder charges no more marks just piercing and cratering. I neck size and bump my shoulders 0.001" to 0.002." I did just have the bolt head bushed recently, but haven't taken it to the range since.

 

[slobhunter2]

This is the method I use

 

[KRP]

I don't think a scale would work because the spring is captive between the two threaded endcaps of the assembly (it doesn't slide).

I think I need a primer on how the bolt cocks the firing pin. The spring is help captive on a rod that's threaded on both ends. The top end piece (closest to the firing pin) sets the depth of protrusion for the firing pin. The bottom end piece, as far as I can tell, either compresses the spring if turned clockwise or decompresses the spring if turned counterclockwise. I don't understand the purpose of the spring in this configuration or by what mechanism the firing pin is propelled into the primer when the trigger is pressed because the firing pin assembly is free floating in the bolt body except for where the cam pin is attached. I'm guessing the bolt created torsional pressure on the spring when rotated, but I'm not sure how that makes the firing pin move forward when the trigger is pressed. I've looked for online tutorials but have come up empty.

The spring is compressed by the cocking sleeve and washer.
The cocking sleeve fits against the bolt assembly screw at the rear and the washer at the front.
With the bolt in the action the head of the cocking pin is trapped in the raceway so the cocking cam in the bolt moves the cocking pin as the bolt is rotated.
The cocking pin is fit into the cocking piece and draws the firing pin back compressing the spring.

Like olddav said: slip the cocking sleeve on, put the cocking sleeve on the scale, then push on the other end.

 

[SingleSeven]

Now it makes sense. Thanks for that explanation KRP. Now that I understand it, I'll give olddav's scale method a try (if we still have a scale - I've been avoiding them for years).

The cartridge is 6.5 CM and the primers are CCI BR-2. I was not expecting piercings with their hard cups.

 

[wbm]

Have you checked firing pin protrusion?

 

[SingleSeven]

Yes, currently set ay 0.049" although I understand many prefer 0.030" to 0.035".