Proper primer ignition

[smoking-brass]

I have a few questions concerning the term( proper primer ignition). The subject is based on comments about modifying the savage bolt firing pin spring. My questions are based on: primers are seated correctly....primer pockets and flash holes are cleaned and true.
1 .Do the manufacturers have a standard for striking force for their primers?
2. If they Do.... how can you measure the striking force of your rifles firing pin?
3. If the primer ignites with less spring pressure how does it effect accuracy?
4. Has there been any field studies done on the subject?
I have always thought if you pull the trigger and the round goes off.... everything
is Good! If it doesn't then Houston we have a problem!
Please enlighten me on the subject... I'm wondering ?
Thanks,
Vince

 

[ShootDots]

I would think that Kelbly, BAT, Barnard, Remington, Winchester AND Savage ALL have different firing pin springs in their respective bolts. Unless there is a SAAMI MINIMUM striking force, it is doubtful that any of the aforementioned action manufacturers have the same firing pin thrust. That being said, IF everything is as it is supposed to be in the loaded round, IF the firing pin strikes the primer with enough force to cause ignition EVERY TIME, I can not conceive how there would be "inconsistent ignition"!! If you have modified your savage bolt to "fit" your liking, and it goes off, I would say you are good to go..

 

[22BRGUY]

I've found that primer seating pressure can affect group size. Some primers like more seating force than others has been my experience.
Best Wishes

 

[smoking-brass]

Thanks guy's for the info....

 

[jlow]

One important thing you are missing in your list is the ignition strength/”flash” of the primer which has a big effect on ES/SDEV

http://riflemansjournal.blogspot.com/2009/06/primers-small-rifle-primer-study.html

 

[smoking-brass]

One important thing you are missing in your list is the ignition strength/”flash” of the primer which has a big effect on ES/SDEV

http://riflemansjournal.blogspot.com/2009/06/primers-small-rifle-primer-study.html

Thanks for the read...I already knew that different primers affect accuracy or sd/es....my point of the post is the amount of force applied to the primer for proper ignition. Thanks

 

[CatShooter]

Thanks for the read...I already knew that different primers affect accuracy or sd/es....my point of the post is the amount of force applied to the primer for proper ignition. Thanks

"Proper ignition" is guaranteed if the primer goes off at all. That is because the priming compound (Sodium Azide) is a true explosive and detonates like TNT - whereas Nitrocellulose is a deflagarent and can only burn.

With primers, once a single crystal "brakes" with enough energy to start the reaction the whole pellet detonates in less than a millionth of a second.

The problem is to have the spring force be the required amount to start the reaction "on arrival" so there is no delay "click-bang" in the ignition - which can give the rifle time to move before discharge - but not more than that amount, because the pin will move the rifle ever so slightly when it comes to a stop inside of the bolt.

So the simple answer is the least amount of force that gives reliable firing.

 

[Steve Blair]

"Proper ignition" is guaranteed if the primer goes off at all. That is because the priming compound (Sodium Azide) is a true explosive and detonates like TNT - whereas Nitrocellulose is a deflagarent and can only burn.

[br]
All that is true except for Tula primer's compound. They use lead styphenate. [br]
http://tulammousa.com/wp-content/uploads/2011/09/TULAMMO_USA_CENTERFIRE_PRIMERS_-MSDS_9_15_2011.pdf

 

[smoking-brass]

Catshooter thank you for the info...Makes perfect sense!

Thanks,
Vince

 

[smoking-brass]

Thanks Steve for the info ....

 

[jlow]

"Proper ignition" is guaranteed if the primer goes off at all. That is because the priming compound (Sodium Azide) is a true explosive and detonates like TNT - whereas Nitrocellulose is a deflagarent and can only burn.

[br]
All that is true except for Tula primer's compound. They use lead styphenate. [br]
http://tulammousa.com/wp-content/uploads/2011/09/TULAMMO_USA_CENTERFIRE_PRIMERS_-MSDS_9_15_2011.pdf

My understanding is most if not all primers you buy off the shelf use Lead styphenate and not sodium azide. The only lead free primers are those that comes from lead free loaded ammunition but they don't sell those as a component.

 

[smoking-brass]

Jlow.... I just checked the msda sheets from cci and they use both components in their primers as stated by catshooter and Steve....that being said you have not gave me and answer on the post subject yet...please enlighten us.
Thanks

 

[spclark]

The only lead free primers are those that comes from lead free loaded ammunition but they don't sell those as a component.

No, that's not entirely true.

PMC used to distribute a line of lead-free 'green' primers a few years ago, made by the same folks making the Murom Plant / PMC / Wolf / Tula primers. They weren't too well thought of in competition circles back then.

Word has it Wolf / Tula lead-free primers are/will be available again here. Midway has 'em on their web catalogue pages but they've been mostly unavailable...

http://www.midwayusa.com/product/3083217711/tulammo-small-rifle-223-remington-primers-lead-free

 

[Webster]

Cannot find the article. Don't remember who published the article. Some primer manufacturers measure the sensitivity of primer ignition by putting a copper or brass cylinder in the primer pocket and measure the depth of the indent. Then they have a spec relating indent depth from that firing pin to some % that don't fire, hang fire and how many fire. I think there was more than three categories.

Nice article by someone at the Air Force Academy.
High speed measurement of firearm primer blast waves
http://arxiv.org/ftp/arxiv/papers/1203/1203.2701.pdf

 

[Old Navy]

[/quote]
My understanding is most if not all primers you buy off the shelf use Lead styphenate and not sodium azide. The only lead free primers are those that comes from lead free loaded ammunition but they don't sell those as a component.
[/quote] +1 Sodium Azide is very poisonous. It was mixed with couple other chemicals and used in the first generation air bags. It was scary stuff to make and handle. We blew up a lot of facilities making it. Later! Frank

 

[jlow]

Jlow.... I just checked the msda sheets from cci and they use both components in their primers as stated by catshooter and Steve....that being said you have not gave me and answer on the post subject yet...please enlighten us.
Thanks

They have both components because they make primers using both, the question is whether you can buy it as a component.

I would think there are answers to everyone of your questions but they would have been done by the manufacturer and not reloaders so they are not available to us.

Sometimes as reloaders we stumble on to questions that are pretty esoteric (not necessarily unimportant) and the only way to answer the question is to do the experiment yourself. If you are willing to purchase a number of firing pins springs and conduct studies with them, you will have your answer. My own guess is if you are working on the bleeding edge of striking force to set the primers off, your first huddle would be a significant number of FTF….
Going the other way, you would be facing pierced primers….

 

[22BRGUY]

Forgive me guys but I think we are still not answering the OP's question which is a good one I think and also of interest to me as to how much seating pressure is required for "proper" or "best" ignition results with various primers or some kind of formula to arrive at the answer. The only thing I can contribute from my experience is that Wolf SRM primers require a strong firing pin spring and "hard" seat to ignite properly....but they do give very low ES numbers when they do work.

Maybe the answer is the same as with many other items, take a certain good load and run a test of say 3 primer pressure seating forces ie: light pressure, medium pressure, hard pressure and see if there is any significant difference in group size...JMHO

 

[CatShooter]

"Proper ignition" is guaranteed if the primer goes off at all. That is because the priming compound (Sodium Azide) is a true explosive and detonates like TNT - whereas Nitrocellulose is a deflagarent and can only burn.

[br]
All that is true except for Tula primer's compound. They use lead styphenate[sic]. [br]
http://tulammousa.com/wp-content/uploads/2011/09/TULAMMO_USA_CENTERFIRE_PRIMERS_-MSDS_9_15_2011.pdf

Lead Styphnate works the same as the Azides.

Of all the explosive compounds available, the organo-metalics (which include lead and Barium Styphnate, Mercury and Silver Fulminate, all of the Azides and Picrates) are the most sensitive for output of any dry, high explosive.

 

[jlow]

Forgive me guys but I think we are still not answering the OP's question which is a good one I think and also of interest to me as to how much seating pressure is required for "proper" or "best" ignition results with various primers or some kind of formula to arrive at the answer. The only thing I can contribute from my experience is that Wolf SRM primers require a strong firing pin spring and "hard" seat to ignite properly....but they do give very low ES numbers when they do work.

Maybe the answer is the same as with many other items, take a certain good load and run a test of say 3 primer pressure seating forces ie: light pressure, medium pressure, hard pressure and see if there is any significant difference in group size...JMHO

Actually if you look at the OP, the question was not on seating pressure but striking force, they are totally different things.

 

[mikecr]

I haven't done scientific testing to define primer striking requirements, but I have found that 'sufficient to fire' is not the same as optimum. All anyone need do is change springs or pin settings with a known load, and they will see this. POI and grouping changes even with every primer firing.
Correct seating according to K&M, which must have come from somewhere back in the day, is 2thou crush. This does not correlate with primer seating forces or cup to casehead. You either measure actual crush, or you're not at a crush standard. Again, primers can fire with very loose seating standards,, not optimum.

About the glass sensitizing implication of setting primers off no matter what -not true at all.
I have crushed primers completely flat with vise-grips(a test) without setting them off, and now & then I deprime live primers, no problem.
You might also notice on your next mis-fire that primer indentation was sufficient, probably as much as any that fired.
I have a 38cal Taurus that is picky about shell headspacing off rims. Wrong ammo never fires, even while there is ridiculous primer indentation. Right ammo(thicker rims) fires fine. So I pull bullets, dump powder and fire this good ammo to see primer indentation,, -exactly the same. The difference- the right ammo in that 38 does not drive forward on striking.
It appears to me not a matter of power in striking, or indentation, but speed of striking.

Kelby nearly hit on some of your questions with his own brand trigger testing -vs- Jewel -with Kelby actions. Here a cleaner release, and optimum striker pull distance obviously changed lock time consistency. But it also changed results down range I guarantee it. With BATs you turn the trigger hanger around, and/or some have changed springs or added weights. I've read where a BR shooter/builder defined proper released pin protrusion from boltface with a popular custom action(and I was also forced to determine this with a Cooper). These shooters are looking at results down range and finding differences beyond click or bang.
I think there is a lot to learn here.