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Old 11-16-2011, 03:11 PM
gotcox

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Post Testing method for firing pin?



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So i was just wondering about proper ignition and lock time and was wondering if there anyone had a method to test for proper and consistent ignition?

Would measuring the rim before firing, then measuring the indent after give you a good reading if the firing pin was hitting the same every time?

And along those same lines is there a preferred amount of crush or impact by the firing pin that one would shoot to have?

And also is there a preferred shape or area of the rim that you would target?

Lets just say you had the chance to make your own action and firing pin. What would you set the above mentioned things too for best and most consistent ignition?

Would appreciate all opinions and thoughts. Thanks guys and gals.

Last edited by gotcox; 11-16-2011 at 03:15 PM.
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Old 11-16-2011, 04:31 PM
gotcox

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Quote:
Originally Posted by MKnarr View Post
Take a look at the beginning of this thread Rim Thickness versus Velocity and it will give you an idea of a 'preferred shape'. I doubt that you would ever get any meaningful data trying to measure depth as I would think that will vary from round to round and brand to brand. Replace you spring frequently get a hit as in the pic and you will be all right.
Great thread dude!!! Wow lots to learn there. Couple local guys still spend a lot of time checking rim thickness and no one can talk them out of it.

So i read you and several others had good luck with either replacing an old firing pin spring to a new one of same tension, or replaced a lower tension spring with a higher one and got better groups and ignition. Is that correct?

Has anyone played around with adding even more spring pressure to the firing pin to see if this trend keeps going or if once a correct tension is met to impact with enough force then any more has no added benefit?

Do you think the better ignition caused by the new spring, in your case, was because of the speed the firing pin hit the case, or the amount it pushed the case in?

Great stuff.
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Old 11-16-2011, 08:26 PM
forrest r

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Buy a chronograph & learn how to use it. It will tell you if you're getting consistent ignition or not.

Lock time & consistent ignition are 2 different things. They will go hand in hand, but only to a point.
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Old 11-17-2011, 08:47 AM
gotcox

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Quote:
Originally Posted by forrest r View Post
Buy a chronograph & learn how to use it. It will tell you if you're getting consistent ignition or not.

Lock time & consistent ignition are 2 different things. They will go hand in hand, but only to a point.
Thanks for the start, but i have some questions about testing ignition this way. How do you determine if the different velocities you will see are from the ignition/FP being setup well and the normal differences that the ammo shows? Is there key things to watch for, or trends in the numbers that will indicate ignition improvements? I assume you would want the ammo to produce either faster number or just more consistent numbers. Thanks

And ya i realize lock time and ignition are somewhat separate, but also both a part of the big picture. I guess in the hunt for proper ignition your going to change lock time by just the changes needed for ignition. So it is kinda a chicken and egg thing, given that ignition is more important for BR i will assume lock time can be allowed to varies were ever it needs to so that the ignition is figured out.

Last edited by gotcox; 11-17-2011 at 04:28 PM.
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Old 11-17-2011, 07:31 PM
forrest r

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If youíre worried about lock time while br shooting, you need to put your front & rear rests down & let them do the work of holding the rifle for awhile.

You need more than 1 rifle to test ammo/ignition with a chronograph. Buy a better quality case of ammo & only use it for testing your different rifles. If you only have 1 rifle, call a couple of the better places that sell match ammo & explain what youíre trying to do. They will have ammo there that theyíve tested & can tell you what the sd they got for that lot of ammo.

What you donít want is 1 rifle consistently shooting a sd of 13 with a lot of match ammo & another rifle shooting a sd of 30 with the same ammo. I have a cz lux that would always shoot 5 to 10 fps more on the sd than the other rifles would with several different lots of ammo. Iím not talking 30 or 40 shots, it was 100ís of shots over a couple month period. After some bolt work the czís sd dropped in line with the other rifles & it showed in the groups it could shoot after the reworking of the bolt.
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Old 11-17-2011, 08:01 PM
gotcox

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Quote:
Originally Posted by forrest r View Post
If youíre worried about lock time while br shooting, you need to put your front & rear rests down & let them do the work of holding the rifle for awhile.

You need more than 1 rifle to test ammo/ignition with a chronograph. Buy a better quality case of ammo & only use it for testing your different rifles. If you only have 1 rifle, call a couple of the better places that sell match ammo & explain what youíre trying to do. They will have ammo there that theyíve tested & can tell you what the sd they got for that lot of ammo.

What you donít want is 1 rifle consistently shooting a sd of 13 with a lot of match ammo & another rifle shooting a sd of 30 with the same ammo. I have a cz lux that would always shoot 5 to 10 fps more on the sd than the other rifles would with several different lots of ammo. Iím not talking 30 or 40 shots, it was 100ís of shots over a couple month period. After some bolt work the czís sd dropped in line with the other rifles & it showed in the groups it could shoot after the reworking of the bolt.
Thanks a bunch forest for sharing your knowledge and experience with me. This is what makes this forum great.

Just out of curiosity what did you do to your lux to get it to shoot the same SD as the others? Higher rate FP spring? Remove weight from FP? Polish the FP and housing for friction free movement?
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Old 11-18-2011, 09:08 AM
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Found one test method for testing FP penetration and consistency. By Mr. Calfee so i thought i would share it here for others interested in the subject.



Quote:
Originally Posted by BC
To determine how uniform our ignition is means we must have some way of measuring some things...

The picture you see here is a simple jig I came up with to allow me to measure, very accurately, the penetration of the firing pin in the case head on the Turbo action....The Turbo has a threaded cocking piece/firing pin which makes the attachment of an extension to contact a dial indicator a snap.....

The 52 Winchester has this same feature.....

With any action some method or other can be found to take this measurment.....but it's just not as accurate to measure with a dial caliper or depth mike as one can do with a set-up like I picture....

In use one of course does not allow the firing pin to snap on the dial indicator stem.....an empty case is chambered, the breech bolt closed, then I retract the indicator stem with my finger, snap the round, then allow the indicator stem to set back against the cocking piece extension...

This is a very accurate way to measure depth penetration....

Like I said on another post, the penetrations must not vary even .001" or there are issues that must be addressed...

The reason we must use fired cases is we're attempting to measure exactly what our ignition system is actually doing...if we tried to measure using live rounds we would incorporate the effect of varing combustion conditions, bullet to bullet, which cause the firing pin depth reading to vary......we're testing our ignition system, not the quality of the ammo..

Using this jig to measure the exact firing pin penetration depth......

One inserts a fired case, then closes the breech bolt slowly, while pulling the trigger, which allows the breech bolt to de-cock, as you lower the breech bolt handle, very slowly, watching the indicator, when it stops moving, note the reading on the indicator, don't allow the handle to close further, open the handle, to re-cock the breech bolt, then hold the indicator stem away and snap the case.....then allow the indicator stem to set back against the cocking piece extension and take the reading.

The difference between the two indicator readings will be the actual depth of penetration of the firing pin in the case rim.

Remember, killer ignition is when we have the penetrations exactly the same, every shot, with enough depth to properly squeeze the rim together, but not so deep as to crush the rim against that steel breech face of the barrel.......

Unless one has some accurate method to measure his ignition, one is just guessing....


Your friend, Bill calfee
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Old 11-18-2011, 09:10 AM
gotcox

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Also found some pictures to show FP strike location.



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Old 11-19-2011, 03:42 PM
forrest r

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You nailed it, did a bunch of polishing on the fp, bolt (inside & outside), new jp striker spring, moly coated all the parts & reshaped the firingpin.

Here's what the fp hits look like after the rework. This is vostock russian ammo that alot of people complained about getting light fp hits on the hard brass cases.
[IMG][/IMG]

I also did the sear/trigger group. Now the trigger breaks like a glass rod with no creap & the fp sounds like someone snapped their fingers when it hits.
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Old 11-20-2011, 12:12 AM
gotcox

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Good stuff! Did some shooting today and keep a bunch of brass, i was shocked and horrified to see the FP marks left. lol I hope to get some good pictures uploaded soon. Looks like i have a lot of work to do.
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Old 11-21-2011, 09:58 AM
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Ok so out shooting this weekend i grabbed a bunch of my brass along with some brass from my buddies guns. Now mine is not a markII 22lr, it is a 9317, but from what i understand it is the same bolt and firing pin for both. My buddy was shooting a ruger 77/17, a CZ 17 and a marlin 22mag. I think the only shells i got from him is the ruger and the marlin. Not so sure. lol


I know the scan didn't work so well. i will try and get mirco pics later.


The 5 rows are the cases from my gun. Measure a case and the rim is .049, where the pin hit is .041 on average for them. That means the fp only hit .008 deep and if you look at the picture closely you can see the fp hits deepest at the edge of the rim and lighter to the middle of the case. The fp hit extends across from rim to center of case about 0.080 When you look at these cases from the side view you can barely make out were the fp hit, there is just that little impact on my gun. Besides the measurable impact also the marks when you look very close show either the FP has a rough tip, bounces a couple times or something else i am not sure of because where the pin hits it has rough marks and is not smooth.

The cases at the top for my buds guns showed a little different with the marlin 22 mag case being the most diff. Measure the rim and get .049 measure where fp hit .039 on average. The 22mag is a whole diff ball park, rim .052 were the fp hit .038 And it is an obvious difference looking at it that the fp hit the case much deeper.

Last edited by gotcox; 11-21-2011 at 11:36 PM.
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Old 11-21-2011, 11:39 PM
gotcox

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Ok so here is a close up of the fp and cases of my gun. As you can see the fp looks terrible, the way it hits the case is not good at all and the depth it hits barely leaves marks.








And a case from my buddies rugar 77/17 showing a much smoother and deeper strike.
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Old 11-22-2011, 06:43 PM
gotcox

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Here is a reply to these questions from another site i thought i would share here for everyones info.

Quote:
"So i was just wondering about proper ignition and lock time and was wondering if there anyone had a method to test for proper and consistent ignition?"

Not really so much of a test more of a visual thing along with cutting cases and looking inside.

"Would measuring the rim before firing, then measuring the indent after give you a good reading if the firing pin was hitting the same every time? "

It probably would if you had a good (consistant ) way to measure the cases.

And along those same lines is there a preferred amount of crush or impact by the firing pin that one would shoot to have?

Yes, you want to close the gap in the rim , You don't need to hammer it shut but it should be closed.

And also is there a preferred shape or area of the rim that you would target?

Yes, rectangular about .070 tall and .040 wide with slightly rounded edges, the target area is just inside the rim edge . You don't want to waste energy crushing the outside of the rim as it serves no purpose.

When does having a higher tension spring lose effect? Like how much stiffer can the firing pin be before you don't see the improvements upgrading from stock ones?

When you upgrade the spring you only need enough extra spring to make sure your closing the rim on every shot, after that your just adding more vibration to deal with.

Lets just say you had the chance to make your own action and firing pin. What would you set the above mentioned things too for best and most consistent ignition?

Ok, I did make my own action and firing pin. The pin tip is about .070 tall and about .040 wide, slightly rounded on the corners as in put it to the buffing wheel and just touched all 4 sides . Just enough to break the sharp edges so as not to cut the case .My firing pin is pretty big at about 3 oz and needs a pretty good shove to get it going . I used the same spring as a turbo just a little longer and probably a little more compression . I'm still trimming it off a coil at a time but I have solid, consistant ignition it just doesn't need to be as hard as it is. my pin hits are just inside the rim . My bolt face is recessed .038 and the max firing pin protrusion is .038 ,the case needs to stop the pin before the mechanical stop does. If I had to guess I'd say some where shy of about .020 deep.

Big pin, big spring, big footprint just inside the rim, and let the case stop the travel .nothing to it.
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Old 11-22-2011, 10:30 PM
forrest r

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Thank you for sharing the info, interesting stuff.

You keep bringing up lock time, whatís the fascination with it?

A few things to keep in mind are lighting fast lock time & perfect fp hits are only going to get you so far.
Any problems with the bbl, bedding, sights/scope, ECT, will negate that perfect fp hit.
If you truly want a rifle with extremely fast lock time then you have to start out with a rifle that has a fast lock time to begin with.
A lot of rifles out there have junk/pot metal firing pins that canít or shouldnít be reshaped/ground & then forced to take the pounding of a stronger striker spring.

Iím not trying to be smart with you, itís just easier to improve a good quality firearm that already has the charastics youíre looking for or are trying to create. I own 3 anschutz for that reason & 3 remington 540 series rifles (Remington themselves say that the 540 series rifles have the fastest lock time of any rifle theyíve ever produced) for the same reason. I saw that the CZ was made with excellent quality steal parts & wanted to see what that rifle could really do.

After the mods that pencil barreled CZ will give any of those 6 rifles above a run for their money. It might not win but it will let them know it was there.

Good luck, go slow & please be careful.
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Old 11-22-2011, 11:48 PM
gotcox

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For my intentions lock time is just a by product of trying to get good ignition and a consistent fp hit. If one of the modifications end up producing a faster lock time as a by product then it is all good. I know that ignition and good fp consistency can only make so much difference, but that is the point. The more small differences i can make to make a good gun great. Some people will always choose to use there wallet to replace knowledge and time, i am not that guy. I prefer to root for the underdog and learn and build what i have.

Last edited by gotcox; 11-23-2011 at 07:45 AM.
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