Firing Pin effect on ignition

Known facts from several sources tests, you are going to need AT LEAST 0.200" fall, AT LEAST 0.045" extension, and AT LEAST 18# of spring to get CONSISTENT ignition with today's small rifle primers!



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alinwa said:
Sorry Blarson but stool and mikeinco are not "others," they're names used by one person who had to change names because guys like you thought he was "mean."

If you'd really searched and understood this subject you'd know that no firing pin has ever poked a hole in no primer.......EVER..... even if you can find opinions to the contrary. Unfounded opinions, un-TESTED opinions, but knee-jerk opinions nonetheless.

In simple fact, the reason I no longer post much here is because people like yourself find this "diversity of opinion" to be more interesting and more "fair" than tested facts.

And more important than safety.


sad

easy, the liberal way is ever filled with support......mob mentality is The New World Order.... garner enough supporting "friends" and you must, by fiat be "right," right?

but sad

Facts aren't up for vote, thankfully! (Although "support" is, sadly. And few care to differentiate)

Go freaking TEST IT before spouting opinions here!!! I'll know you're telling the truth when you tell us how you killed the primers used in the testing regimen.

The op asks a good question, relevant, it needn't be clouded by digressions into banality. Experts across the world, REAL experts, shooters and builders, have documented differences in ignition due to firing pin fall variation. I know of several people who get paid to address this very real issue for shooters in the BR community, and not ONE of them has ever "pierced" a primer. I've spoken with the authors of some of the best books and articles ever written on the subject of accuracy regarding the effect of the firing pin fall/protrusion/diameter/spring weight on accuracy. I know of several systems purposely DESIGNED and built to address this specific topic.......

And none of THEM has ever poked a hole in a primer either...


al
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GEEZ AL............. I`m sorry you feel that way..... did you search and read prior discussions on this site pertaining to piercing primers on this site......?????..... seems others have had firing pins put holes in primers......?????
 
AlinWA could you link us to some material that backs up your statements. I would like to read about this at length. Ive had some very inconsistent ignition problems and now is as good a time as any to learn. thank you sir
 
While you are waiting on Al's answer, while almost any firing pin assembly will set off primers, getting one right for the highest level of accuracy can require a bit more. In fact, it seems that a whole cottage industry has sprung up to improve the most popular actions in short range benchrest. BATs. Such things as spring rate, spring drag on the firing pin, cocking piece drag, and pin weight have all been modified. Beyond the modifications that are common to that brand of action, others may feature firing pins that are supported by their pin tip holes throughout their range of travel during cocking and firing, so that they do not have to find their way into that hole as they move forward during firing. Some have this feature. Others may have their bolt faces bushed to create it. There is also the matter of firing pin tip diameter, and how spring weight relates to that variable. Then we get to shroud fit in the bolt, which can affect accuracy. One thing to keep in mind is that vibrations that originate in the striker assembly influence accuracy. Inconsistencies show up on the target. One more thing, how solidly the cocking piece stays indexed in a vertical plane can be a factor. If it is not, it can hit trigger side plates which can have a negative impact (pun intended) on accuracy. As you can see, there can be a lot more to obtaining consistent fine accuracy than a fresh spring. Some time back, after I had answered a question, the fellow asked if I had any documentation. After I stopped laughing, I told him that I do not document my hobby, I enjoy it, and that most of the really good stuff, that is not in books was shared by friends, and remembered.
 
Many moons ago

Many moons ago back in the early eighties I used high speed film not video to capture the rotation pattern the cross hairs made in a scope when the rifle was dry fired. After looking at a few rifles I soon realized the rifles whose cross hairs did a rotation using a different path each time and or did not come back to the same point it started from usually didn't shoot very well. Those that crossed over at some point were the worst shooters. For want of a term I called it the return to battery effect of the cross hairs...... and yes any likelihood it was the scope was ruled out. In two cases just changing the spring helped the situation.
Andy.
 
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20150925_194042_zpsru5uqxbl.jpg

I tried several different loads and depths, but figured out the pin does have an effect on the group. I was using 450s in every group that has a distinct flyer to the right. I switched to Fed GMM primers and presto, the flyer disappears.

So here's my theory, the harder cups on the 450s are creating inconsistent ignition, resulting a flyer. The wolf standards would blank at this pressure range (wherever that is) so i didn't get to compare the GMM primers against another "soft" cup primer.

Yet it's clear that the primers or primer/ pin combo has more to do with the groups than I really gave credit to.

Adam
 
There is one more thing that you may want to consider. A hotter primer may produce more velocity...and if tune is as Jim Borden puts it "velocity specific" then perhaps adjustments to powder charge are in order so that primers can be compared at the same velocity.

As far as dry fired cross hair movement goes, another variable that I have found affects this is the rear sand bag. Some time back I did a comparison using the same rifle and two different rear bags.

Speaking of dry firing, a friend was having trouble progressing beyond the low twos, with excellent equipment. On one occasion he had packed up his shooting and loading equipment and gone to the range, but found it too windy to work on loads, so I suggested ( I had called him to see how his practice was coming.)some dry fire practice (He shoots free recoil.) That turned out to be very worthwhile. Initially he was able to see some cross hair movement that he did not like, and trace it down to his trigger technique, which he was able to remedy by trial and error, and on a more favorable day get into the ones. In position shooting dry fire practice is well established as a good technique for improving performance, but in benchrest, I find that shooters typically want to hear and feel something go bang. Dry firing, you can see things that get lost in the noise and recoil.
 
Hey Butch.........

This pic, from a few years ago, may be of some interest.

Yes......the primer did not blank.....it pierced.

The 40XBR 17 Javelina had it's bolt bushed by Greg Tannel, and FP turned to 0.060" with a 0.045" protrusion. The old Wolff 32lb. spring had been left in........putting the factory 24lb. spring back in cured the "problem".

Primer.....Fed 205M

Hope this helps.

Kevin
click on pic to see VERY small pinhole.
6gzq6b.jpg
 
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ab_bentley said:
So here's my theory, the harder cups on the 450s are creating inconsistent ignition, resulting a flyer. The wolf standards would blank at this pressure range (wherever that is) so i didn't get to compare the GMM primers against another "soft" cup primer.

Yet it's clear that the primers or primer/ pin combo has more to do with the groups than I really gave credit to.

Adam
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Adam on the CCI450 vs 205GM/s if you are shooting some of the high pressure loads we shoot in 6 BR and Dashers the 205's will not hold the pressure. Contrary to some beliefs magnum primers are not necessarily hotter but they will withstand higher pressures.

Your inconsistent ignition may be because you need a firing pin spring changeout. At Kelblys and Brownells new Wolf springs are in the $20-25 price range.


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JerrySharrett said:
Adam on the CCI450 vs 205GM/s if you are shooting some of the high pressure loads we shoot in 6 BR and Dashers the 205's will not hold the pressure. Contrary to some beliefs magnum primers are not necessarily hotter but they will withstand higher pressures.

Your inconsistent ignition may be because you need a firing pin spring changeout. At Kelblys and Brownells new Wolf springs are in the $20-25 price range.


.
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Hoping this is not comparing apples to oranges: I have found a 5% difference in muzzle velocity between std. and magnum primers (in handguns). If this is not due to the primer being 'hotter', what is the basis for the difference?
 
AMMASHOOTA said:
Hoping this is not comparing apples to oranges: I have found a 5% difference in muzzle velocity between std. and magnum primers (in handguns). If this is not due to the primer being 'hotter', what is the basis for the difference?
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What chrono are you using that you can tell 5% difference in velocity. I would question your chrono's accuracy and inquire to your sample size.

I have Oehler 35 and a 43's and they are not that accurate even with the verify screens. Now if I were to space the screens 20 feet apart and change the clock pulse rate, going to probably a 100 or so sample size might tell us something.

Some where on there are photos of primer spark but that is not an indication of pop!


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JerrySharrett said:
What chrono are you using that you can tell 5% difference in velocity. I would question your chrono's accuracy and inquire to your sample size.

I have Oehler 35 and a 43's and they are not that accurate even with the verify screens. Now if I were to space the screens 20 feet apart and change the clock pulse rate, going to probably a 100 or so sample size might tell us something.

Some where on there are photos of primer spark but that is not an indication of pop!


.
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I am not sure why the brand of the chrono matters. If I shoot the same load with two different primers (std. and magnum) during the same session and see a 5% difference in muzzle velocity, that is good enough for me. 10 rounds of each.

In pistol competition, we use Federal primers almost exclusively, due to its softer cup (consistent ignition with lighter firing pin / striker springs). I have done this test with a variety of chronographs over the last 5 or so years and they have always shown the 5% variation.
 
All this discussion on pin fall, protrusion, spring weight, consistency and blanking.....and no thought of the shape of the firing pin tip?
 
Good Point! (Pun intended )

Rflshootr said:
All this discussion on pin fall, protrusion, spring weight, consistency and blanking.....and no thought of the shape of the firing pin tip?
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Riflshootr, you 'hit-the-nail-on-the-head' so to speak.

It was only after several years in benchrest that I came to appreciate the importance of firing pin tip shape.

Tony Boyer, in his, "Book of Rifle Accuracy" describes perfectly and in great detail the best shape for the firing pin tip. If you do not have a copy of this book, make it priority one to get one as soon as possible.

In chapter 7, "The Action" Tony goes into great detail on firing pins, springs, triggers and other related subjects. There is a perfect illustration of firing pin shape on page 57.

Later,

Gene Beggs
 
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