Fireing pin "bounce" ?

pin bounce???

♠
This thread is interesting, but useless.

Who said that?

Any time you propel and impact a steel pin by a spring coiled around it into a metal surface it will embed itself into the surface and leave the surface and pin in a state of compressive stress after the pin comes to a stop. That compressive stress will be relieved as it propels the pin back in the direction it came from. In other words it rebounds or bounces back. It will happen every time - it's just the way natural physical laws work. All this was "proved" many years ago and we now apply and use these laws everyday in a lot of different ways.

So, ALL pins bounce. The amount of bounce and the time it takes could be computed, and probably with pretty good accuracy. However, it's been my experience on this forum that few shooters really have interest in the numbers - or really have any confidence that they are accurate, or have meaning. Also when the numbers come up trivial, as they often do, then the tendency is to attach undue importance to them - or sometimes just ignore them. In any case, maybe that first statement is correct!
 
♠
This thread is interesting, but useless.
Who said that?
Wish I had!

Things like Firing Pin Bounce, Firing Pin Shape, Indexing your barrel, Cone vrs Cut Extractor Slots, Twists, Grooves & even Head space have very little to do with success at the range.

EQUIPMENT HAS THE LARGEST IMPACT
So you ask what is Equipment?
Equipment is everything you carry to the bench for a match.
 
Last edited by a moderator:
Don said:
Attach an oscilliscope wired accelerometer sensor to the aft end of the firing pin assembly and count how many times the sensor motion reverses itself in 2 milliseconds.................I am 99 percent sure that pin-bounce re-impact does not take place thru the slow mechanical movement of the firing pin/spring assembly in the short 2 millisecond time of cartridge ignition and bullet travel up and out the bore, unless for some unforseen circumstance.

I think Stuart Otteson in "Benchrest Actions and Triggers" calculated firing pin travel time from full cock to impact at appx. 3 milliseconds for a Rem. 700 centerfire pin with a 23 lb spring. Using that as a ballpark figure, you can see that a second rebound strike would take anywhere from a conservative 7-9 milliseconds, assuming the re-cock was not any slower than the forward motion which it is probably not, regardless, none of this comes in less than 2 milliseconds.............Don
Click to expand...

Mr Don thanks for the numbers... It seems from your data any bounce would be a moot point because the bullet "has left the building".

Mr. dave s i respect your views also, "This thread is interesting, but useless.." Kinda hurt my feeling because it is probably true, lol.

Short side bar: In my adventures thru life, mainly motorsports, there are a lot of misconceptions that get repeated over and over as fact. If you try and "tune" with misconceptions your results can be surpassed.

I'm pretty new to rimfire and have heard "f.pin bounce" more than once already. I was just trying to determine fact from misconception. I wouldn't want to leave out a "fact" or add in a "misconception" in my rimfire tuneing, that's why i asked.
Sometimes minutia is critical .... also "if" firing pin bounce can be proved irrelevant, maybe the 'SMITH has other things that are wrong and misleading intentional or not.

We call 'em "killdee's" here in Texas.. Sorta a brown bird with a yellowish belly that nests on the ground in brushy open fields. When your stumbling along about to discover their nest, when your getting close to the "mother load", the momma Killdee flops out across the ground like she is injured, if you were a predator you would head out for her sensing an easy kill.. she will flop and bounce about a 100 yards or so as you chased after her -then take flight to safety!

In life i'm always looking out for that "killdee" -some people are that way. :side bar over:

Besides discussions are fun and interesting, you can read an article but you cannot debate the author. thanks joe:)
 
Doug said:
♠
This thread is interesting, but useless.
Who said that?
Wish I had!

Things like Firing Pin Bounce, Firing Pin Shape, Indexing your barrel, Cone vrs Cut Extractor Slots & even Head space have very little to do with success at the range.

EQUIPMENT HAS THE LARGEST IMPACT
So you ask what is Equipment?
Equipment is everything you carry to the bench for a match.
Click to expand...

Mr Weeter a very interesting comment and i have a tendency to agree. If there is a #1 factor in rimfire accuracy i'm thinking it is Ammo selection, something i had sorta passed over. I have been shooting good ammo but not the best -that has to change if i continue forward.

Mr Weeter since were here -would you mind commenting on what your thoughts are on maybe the top 2 or 3 things in Rimfire accuracy. thanks everyone :)
 
Set back and watched

Joe:
I read some interesting comments to your question, The FP does bounce, but does it affect the accuracy. I do know, that too heavy a FP Spring, will cause additional vibrations that will affect accuracy, but not because in may cause the FP to bounce, but rather that sudden stop when it hit the built in FP Stop. I think that too light a FP Spring will also cause poor ignition. Does the weight of the FP itself, have that much impact on ignition? We still trying to figure out all these questions, and trying to out engineer the manufactures, and all we wind up doing, is cause more questions. I would worry more about the the entire picture like Doug suggested, and practice, practice, practice.
 
I must post a retraction to my post #21.. Since I made my post, I have been in contact with Bill C. and have been convinced of the inaccuracy of my post.. I am now convinced that the firing pin can bounce and affect accuracy, so I apologize to the members of the board that I may have offended..

Dave
 
Last edited:
WOW and now Dave has learned that the "Firing Pin Bounce” Myth has been resurrected as being a Meaningful component of EQUIPMENT!
I guess I well have to retract all I have said because the word has come down from the mount for all to hear. :confused:
 
Doug,
Now that's funny right there! I was thinking the same thing!


JGEE- JUst make sure the pin don't hit the case and the stop at the same time. Next time we talk I'll tell you how to check it. Maybe Calfee will pitch in and tell you here how to check it.
 
Last edited:
jGEE said:
Mr Don thanks for the numbers... It seems from your data any bounce would be a moot point because the bullet "has left the building".
Click to expand...


Yes, I am afraid "Elvis has left the building" before any 2nd strike has taken place, unless someone can show some unforseen rebound activity that takes place within that very short 2 millisecond time frame of ignition and bullet travel out the bore.

Perhaps there is something that looks like a rebound 2nd strike that happens before the end of 2 milliseconds, and affects accuracy..............Don
 
has anyone ever made a seat to go in the end of the barrel made of
softer material that would help the possibility of firing pin bounce?
i'm thinking like how they used to put a valve seat in a car head. of course
the easy way would to be to shape the pin right to start with.
 
Would I be correct in surmising that a heavier firing pin would have a longer dwell time or resistance to rebounding than a lighter one? Conversely, would not the fast lock time pins have an earlier rebound?

Were that the case, then Mr Calfee's no longer with us suggestion that heavier firing pins were beneficial to accuracy might have a justification.

All this assumes that firing pin movement has a measurable effect on uniformity of rifle movement during the ignition/firing process. We can generally see what occurs when we dry fire.
 
The firing pin will rebound or bounce SLIGHTLY. The amount of bounce, that is how far the pin will bounce away from the primer depends to a large degree on the area of the pin tip, the pin dimensions, and the spring load. If amount of bounce is calculated, it turns out to be very small for normal firing pin construction in normal guns.

In center fires with large pin and strong spring the bounce may amount to something on order of .010". In rim fires with small pin and light spring it would be closer to .005". In center fires the pin may be propelled backward as high pressure collapses the indention in the primer but this is not "bounce". It is in effect pressure acting on the pin tip.

"Vibration" that results from the pin's impact, and from the very slight bounce, can be transmitted through the gun and seen in movement of the scope cross hairs of a gun on a rest. Whether this vibration affects accuracy is debatable.
 
Last edited by a moderator:
I don't know the answer to your question. I CAN tell you a little experience I have had with three BR guns.

First is my old 40X that shot so well. I decided it was old and obviously would benefit from a fresh new firing pin spring. So I ordered the two available from Wolff. Both of these springs were much stronger than the one that was in the gun. So.... I changed the spring to one of the Wolff springs. The rifle totally would not shoot. I mean it was really bad. The other Wolff spring was just as bad if not worse. I re-installed the weakling factory spring and the rifle shot great again. Go Figure?

Next is the same 40X with one of Gene Davis titanium firing pin and a pretty stout spring he installs with his firing pin assembly. The poor gun wouldn't shoot worth crap. I could have sold the firing pin assembly but I didn't. I re-installed the factory weakling spring again and the rifle went right back to shooting great.

A few months later I got a new 40X BR rifle from Gene Davis and it had the conventional spring/ firing pin setup. The spring tension is pretty stout just like the Wolff springs. Needless to say it shot great or Gene wouldn't have let it get out of his shop. I figured I'd try that titanium pin/ spring setup in this new rifle. (I can't leave nothing alone). It made the rifle shoot even better than it did before. I couldn't believe it. It's the most accurate and easy to stay on target benchrest gun I have ever shot.

I used to have a Time with the dual firing pins. I bought the gun new and it was junk. I installed a Lilja barrel and It shot OK and won a few matches. Then one day a thread was started here about Calfee trying to get somebody to make an action with a bolt with a 6 o'clock hit. So... I ground half of one of the pins off the Time firing pin and re-installed the long pin at 6 o'clock. The rifle shot much better than ever. It was no slouch before but it became a killer rifle with a simple Dremel tool grind off half of one of the pins.

I guess my point is you just have to try different springs on your firing pins and see what happens?
I couldn't come up with any useful information, but rather just a story of me always having to FIX everything till it's really broke.

Dale McClure
 
You must log in or register to reply here.
Back
Top