Firing pin spring weight as issued from Savage

[Bark]

Would be interested in hearing the OE firing pin spring rate for a LA as it comes from the factory.Also,are any of you running the Wolff 32/36 lb's or even the Tubbs Speedlock spring? Thanks, Old Grumpy Bark

[Uncle Jack]

I don't know, but I was wondering just today why you never hear much about firing pins, firing pin springs, and concerns about "Lock Time" around here. People concern themselves a lot with barrels, twist rates, bedding, and triggers and seem to completely ignore the ignition system.

uj

[docsleepy]

do you mean the spring contant (lbs/in or newtons/meter) or the spring velocity or the mass of the spring?

[82boy]

You will have to talk to Sharpshooter when he gets back he can tell you the speck weight of the springs. (I believe it is around 26 lbs) I do know that Savage has a variant in spring rate, and they are never to speck. (I know it is much heavier than needed, even at speck.)
On lock time, the reason why it is hardly mentioned is because a Savage has one of the fastest lock times around. It is far faster than a Mauser, or other mass produced gun. There is no need to improve it.
On Wolf springs, One of the biggest complaints of the Savage action is the hard bolt lift. Increasing the spring weight is only going to make the bolt lift harder, and give you nothing in return. I don't believe that Tubbs even offers his speed-lock spring for a Savage anymore.
I am no expert in this area, Hopefully Sharpshooter will chime in in a day or so, and explain it better than I can.

[Bark]

do you mean the spring contant (lbs/in or newtons/meter) or the spring velocity or the mass of the spring?

....lbs/inch,I'm a hick.While we're at it,perhaps you can tell me who put the bop in the bop su bop su bop,eh mate? Old Grumpy Bark in the woods

[sharpshooter]

The only difference between long action springs and short action are the compression height at which they are tested. Mean measurement is 23.5 lbs.+-5%, at their respective compression height. Most I have tested far exceeded the max.
Speed lock springs and firing pin kits are a gimmick, and they offer no good what so ever, in fact they have a tendency cause more problems. Lock time is insignificant and not worthy of worrying about, but consistant ignition is paramount.

[Bark]

Thanks for all the replys,guess I'll leave the Wolff in the cave.It just goes against my motto....."if it ain't broke,fix it till it is".By the way,nice trigger Fred.Really nice trigger.Thanks for getting it out before leaving for SHOT. Old Grumpy Bark

[Smokepole]

I went down in firing pin spring rate drastically to improve bolt lift equally drastically. The factory SA spring is 1" shorter relaxed length than the LA spring relaxed. The Savage puts out WAY more than enough strike energy so I elected to source a lighter spring. From Otteson's "The Bolt Action Rifle", the LA puts out 117.9 oz-in of strike energy whereas only 75 oz-in is needed, even w a healthy safety factor. As Otteson states, the US Army requires reliable ignition at 64 oz-in for LR primers. A commercial company says that 63 oz-in is needed for perfect ignition in a production firearm. 75 oz-in is the goal of that particular commercial company in a production firearm. Obviously, that company isn't Savage. I used this info and various spring/energy calculations to generate a new spring rate to get that 75 oz-in. I sourced some springs, and it's been working just fine for awhile now. Lock time does go up, but it's still faster than most all other bolt actions on the market.

[RWO]

On my target action(SA), I measured(rather crudely) the spring rate at 18.3#/in. It's made from .055 wire. The calculated energy is 102.3 in.-oz. and lock time is 1.9 msec. I made a new spring with the same size and number of coils out of .051 wire. It's rate measured at 14.5#/in. Calculated energy dropped to 80 in.-oz. and locktime increased to 2.1 msec. Bolt lift eased significantly . I have not had a chance to shoot it yet.

RWO

[sharpshooter]

Calculated energy is just that, calculated. How much actually ends up hitting the primer is a different story.

[Smokepole]

I stated there's already a healthy safety factor included in that 75 oz-in to cover all frictional losses and off-center primer strikes. I also stated that the 75 oz-in figure is the goal of a major firearms producer to further back my reasoning. Without engineering and the accompanying calculations, there is nothing. Civil engineers don't build a bridge, see how much weight it takes to collapse it, then build another just like it to give it a weight rating. It's not real cost effective, or smart.

So what load cells and associated measuring equipment have you used to determine what the actual strike energy is? It can't be a real easy thing to accomplish nor is the proper equipment cheap. An empirically measured figure would be very much appreciated by us here. Better yet, a bell curve of LOTS of measured figures from a test lot of Savage actions would be more trustworthy and informative. If we knew that, we could better estimate the losses, and better our worthless calculations.

[RWO]

I would like to see the calculated values (before and after) for one of Sharpshooter's famous T&T action jobs, assuming that he modifies the firingpin/spring mechanism. How about it, Sharpshooter?

RWO

[Blue Avenger]

Last I knew he was not a fan of messing with the spring pressure. don't fix what is not broken.

[Smokepole]

Spring rate is only part of the equation, preload and travel have just as much to do with the energy and lock time. That's where those worthless calculations come in quite handy.

[docsleepy]

I am impressed! Lots of quite technical info known by you fellas!
gordon

[sharpshooter]

There's alot of speculation in your last post. It is true I reduce the cocking ramp angle, but I gain firing pin travel, use less spring and gain impact energy. Because I'm not that great at calculus, I put that task to someone that is. I did not do the first calculation, but I actually did a physical experiment that proved that I gained impact energy, and from that data, had it calculated. This was realistic information.
The information in Stuart Otteson's book contains some incorrect data for the Savage long action that does not reflect a true cross section of specimens, nor does it take into consideration the effect of sear resistance.
The data I collected was passed on to John Peirce(Peirce Precision Engineering) for calculation and then to Bruce Thom (BAT Actions) for confirmation.
The final numbers are as follows: impact energy- 4.4 in/lbs. lock time-2.0 ms.

[allan1066]

This is really great detailed stuff guys - Can you just sum it up for me and tell me how many coils I can chop off the standard spring for 12F target action, to aid bolt lift while still giving it enough wack to make it go bang?

[Smokepole]

So, how do you gain firing pin travel and simultaneously shorten the ramp (cocking distance) w/o having a rebounding firing pin? Earlier you stated that consistent ignition is paramount, and it is. Your measured data puts your actions at 70 oz-in, which is right on par w what my spring choice is.

It's not calculus in this case; it's algebra. I do not believe Otteson's data is erroneous. He clearly states the assumptions and conditions he uses to arrive at his conclusions. To call out a published and well accepted book is quite a bold move.

[82boy]

This is really great detailed stuff guys - Can you just sum it up for me and tell me how many coils I can chop off the standard spring for 12F target action, to aid bolt lift while still giving it enough wack to make it go bang?

Do not cut coils off of the spring, this is a bad idea.

[Smokepole]

Shortening the stock spring is indeed not the best idea. You're decreasing preload, not the actual rate of the spring.

[Bark]

Very intresting indeed.Going solely on the feel and percieved impact on an A-Zoom,I would never have guessed abundant headroom on the strike.Also,locktime seemed a bit sluggish on the Savage,but I spend the majority of my triggertime on a Perrazi servicing a trap addiction.Having been involved for over 20 years in precision airguns(another addiction to be avoided) which are spring intensive,I've had many custom srpings wound at approx.$90 a pop local before I found these guys http://www.leespring.com/ Just measure length,mic the wire,and go up or down depending on need.Download the catalogue and off you go.Very easy people to work with.Sure do love these Savage rifles,acres and acres to play on. Old Grumpy Bark

[sharpshooter]

First of all, cocking distance will never be equal to firing pin travel. By using a little common sense you should realize that. If you would actually physically measure it, you would see. How I gain firing pin travel is a trade secret. Like I said before, it took me 3 years to figure this out and I work on hundreds of actions a year. When you get that many under your belt, you'll have it figured out too.
I was never any good at algabra either, that's why I put the task to someone who is. Ottesons formula may be correct, but the numbers he uses are not. Like I said before the data he collected does not match what I have collected over 10 years and hundreds of actions. Garbage in-garbage out, if the numbers are not right, the end result is not right. Just be cause it's published and well respected, does not mean it's accurate.

[Smokepole]

My common sense is failing me. Do tell. How can the firing pin possibly travel further than from the top detent to the bottom of the ramp (or the back of the bolt head)? It can surely travel less, if the primer is in the way, but I don't see how it can travel more. If you're worried about your trade secrets, get a patent.

As for Otteson's numbers, they seem to jive just fine w what RWO and I have measured on our individual actions. Measuring the spring rate is easy enough. Measuring compressed & relaxed lengths is easy enough. Allowing for sear friction/resistance is easy enough because it's almost negligible in relation to the amount of energy in the mainspring (which is one key omission Otteson makes and clearly states). The same can be said for friction elements between the firing pin and surrounding parts as well. I fail to see how Otteson, RWO, and I are so far off.

[TheShootist1894]

Allowing for sear friction/resistance is easy enough because it's almost negligible in relation to the amount of energy in the mainspring (which is one key omission Otteson makes and clearly states).

Negligible? So if you have 6-8 lbs of sear resistance acting against a 25 lb spring you call a 33% loss negligible? I think not, granted a 10 lb spring will probably set off the primer sometimes, but will be inconsistent at best. . . .

[Smokepole]

I doubt it's that much resistance, especially since I run a lightened or well worn sear spring. Take a look at that small torsion spring on the sear and compare it to the mainspring. See how much leverage the upper sear tab has on that torsion spring. Also, remember, that's a ramp on the sear. The cocking pin has LOTS of leverage on it. And what's more, that leverage increases as the sear drops out of the way (the ramp gets shallower). Most of the resistance will be purely frictional there. So yes, I call it negligible and include it in the safety factors between 75 oz-in and what actually is needed to pop an ideal LR primer. It's nowhere near 6-8lbs once the trigger breaks.

Another way of looking at this whole situation is as a closed system. At the end of the day, the input is a 90* throw w a force at the end of a lever arm, torque. That is an input energy that's converted to stored potential energy in the mainspring. That energy is then released to strike the primer. So, the only way to get a lighter throw is to decrease the energy of the primer strike or spread the input load out more evenly across the opening and closing of the bolt so you just don't 'feel' as much force. You're applying a smaller force over a longer distance. Same amount of energy in, but it doesn't feel like it. And there's a number of ways to accomplish that.

Can/will anyone here answer my question?:
"How can the firing pin possibly travel further than from the top detent to the bottom of the ramp (or the back of the bolt head)?"

And it still raises my eyebrows that someone would call out a published and well respected work as garbage. That says quite a bit in my book.