Firing pin, springs, FTF.

[Rocketvapor]

Pushing an unsprung pin through the bolt to measure total drag as it passes the sear?
A few thoughts come to mind (RV be thinking, that be BAD :) ).
Smooth and blend sear above where it contacts the cocking pin , change angle/shape a little, BUT, don't reduce pin travel from decocking. Find a suitable sear spring with a little less strength, change cocking pin diameter where is rides on the sear. .\


Would increasing spring force with the adjusting nut, shortening the pin's sprung length, then reducing spring O.D. a tiny bit for a couple of turns for the same preload give a higher impact energy?

[Dave Hoback]

As to the question, I wouldn’t have any knowledge of the 4.0-5.8 numbers. While I’ve also studied Force & Impact energy a great deal (albeit, not 20 years)with the ignition of ammunition primers being part, those are numbers sharpshooter developed based on a test he created. So it’s not information I would ever have studied. I doubt any expert having been published in the field of impact energy would have any knowledge of those numbers either. I do agree with him it is simple though. To me it’s as simple as Too much is overboard & Too little ain’t enough! As to the subject at hand, the United States Military adopted, under testing performed & established by Frankford Armory, that 48 Inch Ounces was the bare minimum for primer ignition. In the general speaking, it’s been said that 6Ft.Lbs. of energy is needed. When you learn enough on the topic, it’s finally realized there really is no number that can quantify the end result. David Tubb did a fascinating article on the topic which was very informative. (I don’t have it handy) In other discussions on this topic, others may remember I’ve said I don’t believe striker impact energy affects bullet velocity. I know others have done their own private testing and believe it does, however, experts agree there is no evidence to proving either argument. Some believed Yay some believe Nay. Once again I’ll say simply, Too much is overboard & Too little ain’t enough. Meaning, too much spring behind the firing pin just causes extra bolt lift & wear on parts. No one having credible knowledge of the Savage 110 would ever recommend using a Wolff 32Lb. spring! And on the other side, being Too little: if the rifle is exhibiting light primer strikes and the spring has been diagnosed as the cause, it needs replaced, or can possibly get away with pre-loading.

[Dave Hoback]

Delete

[Dave Hoback]

This has digressed into a general discussion on pins with most not liking the new style.
Not just about you but general useful info.
Maybe not the correct thread for this.
Set one of the old pins for 0.045".
10264
One more quarter turn would be (-0.00893") or about 0.036".
That too short?

Not at all. .036” is about perfect. (.035”) I’m at about .032” I think, right now.

[Rocketvapor]

Thanks Dave.
I've got a complete 6.8 bolt set up (new style) with the pin @ 0.047", a 3 piece thrust bearing and a thinned BAS washer.
I'll let her take some shots with this.
I've got enough parts to set up a pair of .223 bolts, one old, one new pin. I'll polish down the new pin some (0.060" just looks scary) and set the old one for another quarter turn in from the 0.045".


Now to get my FFL to order a couple of sears for this receiver.
Oh boy, another science project, hehe

[Dave Hoback]

Definitely bring it down from .060”! All that extra protrusion is just limiting firing pin travel.

[South Prairie jim]

You adamantly a couple times stated "one last time" which was not just dismissed by me, the one with the question, looking for an answer. Your first response was a short one sentence cause and effect back in post #12 w/o any real explanation. Yet the very last sentence in my very first post was that I had already purchased a new pin and springs which should have indicated that I already suspected this as a cause and agreed with you even though I did not understand the reason why at the time.. Once again exactly why I came to this forum asking guidance.

At the same I had also previously seen the picture posted in #8 and had conversations with Dave about firing pins long before this. Which I where I learned of the known problem with Savage bolt heads and firing pin holes being sloppy and why many have them bushed. To help eliminate the cratering around the pin dimple.

Post #17 I asked the question once again looking for clarity. Maybe I posed the question the wrong way. As here we are now at post #76 and not a single member can explain why these cases have behaved the way they did. Still not one here can believe that I say I measured these cases before firing and after failing to fire and that they have all gotten shorter after failing. Most are saying or implying these cases were too short to begin with when I know for a fact they were not. But once again that seems to be a complete separate issue and not related to the FTF issue. But still at this point I was questioning the firing pin and springs.

So then in post #47 I directly asked you to explain your response which you directly responded to in past #61 to which I directly responded to in post #63 and Graciously thanked you for the lengthy explanation. Also tried to express that at this time I have to make due as I do not have the time to order and wait for new parts as they would never arrive before we start out league. Then completely flabbergasted by the response in post #64 which implied I completely dismissed your advice. Thanks Jim!

Anyways I am able to proceed the way it is and get started with the league. I was able to find a load that this bullet seems to like and is shooting much tighter than the 69gr SMK I shot last year. This week I will be ordering new pin parts.

Lastly to your post at #70. Fliers are also a sign of an inconsistent shooter. Me! And I admit that fact. I have a lot of inconsistencies I'm working on! :redface-new:

Sorry if you were flabbergast by my suggestion to make time, there’s no need for hostility I’m just being honest and hopefully helpful, I’ve been through ignition issues and they can be frustrating and once isolated and corrected require a little re-tuning /tail chasing to get back where you want to be. Remember that you are the one that asked and several guys had quality input.
Guys can ask questions on open forums but no one is entitled to detailed answers.

[South Prairie jim]

I actually regret getting involved in the first place. I’ll know better next time and just keep my big mouth shut.

[Robinhood]

Well, it's pretty simple, but most people don't have the tools or measuring equipment to get the numbers.

Firing pin travel to the boltface, which is total travel, minus firing pin protrusion. (for example) .285" total travel......minus .035" protrusion, = .250"
Net spring force, which is force at full cock, minus sear drag. (for example) cocked 23.5 lb....minus sear drag of 4.2 lbs = 19.3
.250 x 19.3 = 4.825

Thanks Fred. Is the drag number an absolute or it just a constant that worked well in your calcs.

I appreciate all that I have learned from you over time.

"I actually regret getting involved in the first place. I’ll know better next time and just keep my big mouth shut."

I hate it when i feel like that.

[South Prairie jim]

Yep, I know several very knowledgeable guys that just won’t post any more, partly due to negative feedback. If anyone remembers mr. F Guffey, he would always give me these cryptic clues that looking back were intended to make me think and figure it out. Some guys just don’t like typing.

[shoots100]

Post #17 I asked the question once again looking for clarity. Maybe I posed the question the wrong way. As here we are now at post #76 and not a single member can explain why these cases have behaved the way they did.


You don't seem to realize that you answered the question.
Since you stopped using Hornady brass, you've had no issue's with shrinking brass or FTF's.
One could come to the conclusion that the sub par Hornady brass being reloaded one too many times was the cause of the issue.
Brass fatigue will eventually happen to quality brass after too many reloads.
That's why match shooters will dump their brass after reloading them a certain amount of times, even if the brass looks good.
At least you didn't learn this lesson while shooting a match.

SJC

[charlie b]

I still think the 'shrinking brass' was related to the failed ignition. I've had it happen numerous times when a round fails to fire or with 'mouse fart' loads.

[South Prairie jim]

I still think the 'shrinking brass' was related to the failed ignition. I've had it happen numerous times when a round fails to fire or with 'mouse fart' loads.


Interesting topic and worthy of its own thread…
Does anyone really know which direction a case expands firstly inside a chamber being fired? Does the case expand in radial to the sidewall then lengthen ? We know that when sizing a tapered case they always get longer before they get shorter because we can measure the results as we adjust the die but is that reversed during ignition ? IDk because I’m unable to observe during ignition.

[Dave Hoback]

Interesting topic and worthy of its own thread…
Does anyone really know which direction a case expands firstly inside a chamber being fired? Does the case expand in radial to the sidewall then lengthen ? We know that when sizing a tapered case they always get longer before they get shorter because we can measure the results as we adjust the die but is that reversed during ignition ? IDk because I’m unable to observe during ignition.

It expands in all directions as that is what the powder burn is trying to do. It is stopped by the casewall and obviously by the thicker case head and bolt face, then continues traveling forward to the shoulder of the chamber & finally case neck.

[South Prairie jim]

It expands in all directions as that is what the powder burn is trying to do. It is stopped by the casewall and obviously by the thicker case head and bolt face, then continues traveling forward to the shoulder of the chamber & finally case neck.

We assume, but how do we really know ? Some guys suggest the firing pin drives the case forward to the shoulder prior to expanding laterally. Isn’t it all just speculation ?

[Rocketvapor]

Well, it's pretty simple, but most people don't have the tools or measuring equipment to get the numbers.

Firing pin travel to the boltface, which is total travel, minus firing pin protrusion. (for example) .285" total travel......minus .035" protrusion, = .250"
Net spring force, which is force at full cock, minus sear drag. (for example) cocked 23.5 lb....minus sear drag of 4.2 lbs = 19.3
.250 x 19.3 = 4.825

I really hate posting here again, but could someone interpret my measurements on one of the dreaded New style bolt/pins?
Pressing on the bathroom scale with the cocking indicator touching my thumb in the BAS hole I get 23.5 lbs on the short spring, 32 pounds on the midlength spring, and forget it with the big spring, over 40 lbs.
http://www.savageshooters.com/attachment.php?attachmentid=10266&d=1704176199&thumb=1 (http://www.savageshooters.com/attachment.php?attachmentid=10266&d=1704176199)
Here's the "INPUT DATA" for the small, weak, worn out spring installed in an assembled bolt.
Force required to lift off cocking notch 24.5 pounds.
Force require to lift off Bolt Head @ full fall, 10.5 lbs.
Using this and a 200 pound industrial scale.
http://www.savageshooters.com/attachment.php?attachmentid=10277&d=1704298918&thumb=1 (http://www.savageshooters.com/attachment.php?attachmentid=10277&d=1704298918)

Pin measurements (from cocking indicator)
Cocking notch, 0.005" to indicator,
Cocked and on sear 0.028",
Fired 0.288".
Protrusion is 0.044-0.045"

I think there was a formula posted in one of these threads.
Found it.
Sounds like I will lose about 0.020" in pin fall (at full impact of primer) from a 0.045" protrusion, and about 4 pounds due to sear/cocking pin friction/drag.

So far, this rifle has had ZERO Misfires :)
(out of ZERO shots)

[Dave Hoback]

Rocket, there’s really nothing to take from your measurements. Unfortunately, there are too many variables, you have no Control variable, and once again, any testing any of us can do is rudimentary at best. Tell Ma, what is it are you trying to understand? I answered your question on the springs in your Build thread. The long & short springs are the same factory spring. It’s just the old one from your rifle has taken a set at the compressed length. As a result, it has lost a portion of its energy retention. Honestly, anything we can do is just going down a rabbit hole. None of what we do is scientific. No one here has the equipment to come close. None of us!

Honestly, this will end up turning into another one of those ridiculous discussions like the one about people believing they could calculate the milliseconds of fire & projectile exiting on the x-number of barrel reverberation, yadda-yadda, or a discussion on Tuning the Action screw torque. When loading can do do it easier & better. LOL!

[charlie b]

We assume, but how do we really know ? Some guys suggest the firing pin drives the case forward to the shoulder prior to expanding laterally. Isn’t it all just speculation ?

The cast bullet folks have theories, but, they are just that. I have never seen conclusive proof of any of it. I have had case shoulder setback from just the FP impact.

One is that the firing pin shoves case forward and then the expanding gases force it back as the bullet is pushed from the case. Not enough pressure to 'form' the case to the chamber so the neck remains set back.

Another is the primer ignition pressure inside the primer cup is enough to force the case forward. The case pressure eventually pushes the case back over the primer, but, not enough pressure to reform the shoulder. These folks will drill out the flash hole to reduce the area over which the primer pressure acts. I don't know if that is the 'fix' or if the additional flame front acting on the reduced powder charges creates a higher pressure earlier in the cycle, which could prevent the setback.

Long ago there were theories about how a case reacts in the chamber. Case is shoved forward by force of striking primer, pressure builds, the thinner portions of the case 'grab' first, then the web and base are forced against the bolt head. (This is one that is used to support the mode of case failure when the case head separates) Aggravated if there is excess headspace or a case is resized a bit 'short'. But, some of those who size to an 'interference' fit still might see case head separation (I've never had it happen to me, knock on wood :) ) so is this a realistic scenario?

None of this is really relevant unless you are using fired cases and primers to deduce a problem with shooting. And that is complicated by how many times cases were fired/annealed, actual pressure curves, case volumes, case wall dimensions, sizing, etc, etc.

[South Prairie jim]

The cast bullet folks have theories, but, they are just that. I have never seen conclusive proof of any of it. I have had case shoulder setback from just the FP impact.

One is that the firing pin shoves case forward and then the expanding gases force it back as the bullet is pushed from the case. Not enough pressure to 'form' the case to the chamber so the neck remains set back.

Another is the primer ignition pressure inside the primer cup is enough to force the case forward. The case pressure eventually pushes the case back over the primer, but, not enough pressure to reform the shoulder. These folks will drill out the flash hole to reduce the area over which the primer pressure acts. I don't know if that is the 'fix' or if the additional flame front acting on the reduced powder charges creates a higher pressure earlier in the cycle, which could prevent the setback.

Long ago there were theories about how a case reacts in the chamber. Case is shoved forward by force of striking primer, pressure builds, the thinner portions of the case 'grab' first, then the web and base are forced against the bolt head. (This is one that is used to support the mode of case failure when the case head separates) Aggravated if there is excess headspace or a case is resized a bit 'short'. But, some of those who size to an 'interference' fit still might see case head separation (I've never had it happen to me, knock on wood :) ) so is this a realistic scenario?

None of this is really relevant unless you are using fired cases and primers to deduce a problem with shooting. And that is complicated by how many times cases were fired/annealed, actual pressure curves, case volumes, case wall dimensions, sizing, etc, etc.

I’m thinking that the extractor is holding the case to the bolt face with opposing pressure from the ejector, I don’t visualize the case moving forward much at all. Although I’m certainly no expert. Once the primer is struck the flash goes toward the powder I’ll suggest force has to be the opposite direction again holding the case against the bolt face. Certainly the weakest part of the case is the mid sidewall where we typically see case separation from excess sizing over time ( personal experience here), therefore can we theorize that the case expands to the chamber wall during ignition prior to extending in length towards the shoulder ? We know from experience that it may take more than one firing to completely fire form a case in length before extraction becomes difficult and set back is required. Perhaps herein lies a clue to the mysterious shrinking case.

[charlie b]

Yep, perfectly valid theory.

I've fired a bunch of cases that never had the shoulder set back (neck size only) and they work perfectly well after more than 20 reloads. These were with moderate to low charges. As you said, full powder charges tend to start 'sticking' after 4 or 5 reloads when a FL size is 'needed'.

FWIW, the times I had shoulder set back from a FP hit were with my cast loads. Those are bullets seated to a jam fit in the throat so there is no gap at the bolt head.