Firing Pin Shape.

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Firing Pin Shape.

Post by boomer47 » Wed Sep 07, 2005 7:47 pm

I've been wondering why I never have a misfire with my Marlin 81TS bolt action rifle and see so many posts about failure to fire with the Ruger pistol.
So, I pulled the pin out of the Marlin and THINK I see a major difference. The Marlin pin is of course heavier and has a blunt square end that hits the primer plus a stronger spring so it hits the rim and primer with more force than the pistol pin.
I took the firing pin out of my Hunter and filed a blunt point on the business end, then used a small round file to remove a little metal at the rear of the hole in the pin that the firing pin stop goes through.
I miked the pin before and after, took 0.005 off the end of the pin and enlarged the rear of the hole in the pin by the same.
Now, instead of a sharp dent in the rim I'm getting a wider,deeper, flat impression on the case rim.
I haven't been to the range with it yet but did fire 40 Aguila Colibris(no powder, just primer.Neighbors get upset with loud noise ya know) through the Hunter today without a failure to fire and compared the cases to some Federal cases that I had shot and swept up the last time I was at the range.
The Colibri cases all showed a much wider and deeper dent in the case rim than the Federals that I had shot using the factory firing pin.
I also checked to make sure that the firing pin was not hitting the chamber edge when dry firing then called Ruger to order 2 more firing pins just in case I've got this all wrong.
This mod just might help those who are having ftf's with different ammo as I have shot just about every brand of .22 ammo made, and lots of it, through the Marlin without a ftf and I think the broader,stronger firing pin hit makes some of the difference.
Also, I have seen ads for weaker mainsprings that give a better trigger pull. Anyone know where to find a stronger mainspring that will give the hammer a little more oomph?

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Post by Bullseye » Wed Sep 07, 2005 8:24 pm

Boomer it sounds like you are on to a good research test project. I'm interested to hear your comparitive analysis of the wider firing pin face. In order to fairly examine the changes you propose you'll also need to test an unmodified factory firing pin as a baseline sample on all the ammo you test the modified one on. That should be no problem since you have some fresh new virgin ones coming in the mail.

Most people are looking to put in lighter mainsprings or lighter hammers. A lighter hammer will decrease lock time but the lower hammer mass may not have the effect in the firing pin force you are trying to measure.

A heavier spring would add more stress on the firing pin stop and could cause stress fracture failures at a significantly higher rate, leading to more damaged chamber faces from unseen firing pin hits.


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Post by boomer47 » Wed Sep 07, 2005 9:13 pm

Bullseye,
You make some good points.
One other project I've considered is to drill a hole lengthwise in the hammer and fill the hole with lead to give the hammer a little more weight to smack the firing pin with.
With all the ftfs we hear about I just can't see a lighter hammer such as the VQ nor a lighter mainspring.
Faster locktime and lighter triggers are fine as long as the pistol goes boom EVERY time.
I'm sure the ammo has a lot to do with the ftfs in the semi- auto pistols but as I said before, my bolt action rifle handles them all with no ftf so there must be an answer to the problem with the pistols.
Now to find the answer----

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Post by Bullseye » Wed Sep 07, 2005 10:47 pm

I think there's some validity to your hypothesis about the firing pin. When I want to test ammo for detonation failures I'll test cartridges that FTF'd in a pistol in a rifle and see if they will fire. Typically, I'll attempt a restrike in the pistol but I'll save some for rifle tests too.

Use the scientific method. Test and record observed results. Avoid testing to achieve only favorable results or ones designed only to achieve a specific desired result. Let the chips fall where they may and draw conculusions from direct observations only; this is the only proper way to run an effective test procedure.

Good luck and I look forward to seeing your results.

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Re: Firing Pin Shape.

Post by toyfj40 » Wed Sep 07, 2005 11:28 pm

boomer47 wrote:I did fire 40 Aguila Colibris(no powder, just primer.Neighbors get upset with loud noise ya know)
Novice Comment: I understand that Aguila uses the Eley Primer.
By using Colibris to be quiet... could this initial test produce a
False Positive ? Due to the Colibri/Eley being a better Primer.

Excellent Observation(tm), I hope it produces something that you can get
a patent and get rich enough to be protected by the new legislation. :lol:

I've noticed more Fizzle-Fires from Rem-ThunderBolts.
They fire but noticably weaker... more like a PelletGun-Pwr-level...
Thank-you for the GunSmithing/Ballistics insight.
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Post by boomer47 » Thu Sep 08, 2005 9:17 am

toyfj40,

You are probably right about the Aguila primer but, this was not a lab test.
I was mainly looking at the difference in the size,shape and depth of the firing pin indentation on the case after the mod. I believe it makes a difference.
It will be awhile before I have time to run a batch of differing ammo thru the pistol but if I start getting the wrong results early I'll post back here to let everyone know that I'm on the wrong trail.
I'd like to see a survey on ftfs in the Ruger semi-autos based on different ammo. That should go a long way in deciding whether it is a pistol or ammo problem.
Maybe if we get enough interest(replies) in the project Bullseye will start a sticky on that.

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Post by toyfj40 » Thu Sep 08, 2005 11:23 am

boomer47 wrote:Maybe if we get enough interest(replies) in the project
give some thought to a Score-Sheet that would list the
data/info that would help in a Comparison... and we could try an
UNscientific evaluation of Apples and Oranges... Those of us with
Stock-FiringPins/Springs could track Things and report
them here... to identify ABOVE and BELOW normal cartridges.

I need something productive to do at the range...
as I sure have trouble keeping my groups tight ! :oops:
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Post by boomer47 » Thu Sep 08, 2005 11:29 am

Good idea.
glockguru has a thread going on the mk11.org site about tests with a Hunter and different ammo and so far he is not reporting many ftfs.

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Post by boomer47 » Fri Sep 09, 2005 10:39 am

I hope the pic turns out.
I went out and shot 25 each of the following using my modded firing pin.
CCI MiniMag
Win. SuperX
Federal Spitfire
Win. Dynapoint

No ftfs at all.

If the pic comes through you can see a big difference in the indentations on this case compared to the shallow, pointed dent using a factory pin.(both of these strikes are with the modded pin)[img]

http://i2.photobucket.com/albums/y36/bo ... 0_0082.jpg

These firing pin strikes look more like the strikes my rifle makes. One of them was the actual firing, the other I made on the empty case just for comparison.

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Post by Bullseye » Fri Sep 09, 2005 7:38 pm

You're right Boomer, that firing pin footprint appears considerably larger than a factory firing pin.

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Post by boomer47 » Sat Sep 10, 2005 7:12 pm

Bullseye,
I don't have a range close enough to shoot every day, so I can't really run the tests suggested here.
I will keep up with the different brands of ammo I use and report back about any ftfs I have with the reshaped firing pin.
If you look at some of the .22 rifle forums you will see lots of problems but seldom see anything about a ftf in a bolt actin rifle which,along with my own experience with a Marlin .22 bolt action, is what got me looking into this.
Given the fact that we know how a .22 case is primed the ideal firing pin would be circular and strike the entire outer rim of a rimfire case in order to make sure it did not strike a spot in the rim with little or no primer compound under it.
But I doubt that any firearms maker would go to the trouble and expense to fix such a small problem. I just believe that if a ftf occurs with a pin strike that is very sharp,shallow and narrow then a strike that is much wider, more blunt and deeper would go a long way to solving the problem because it has a better chance of hitting a spot on the rim with primer compound under it.
In any case I'm going to leave my modified pin in and shoot when I get a chance and will honestly post back here if I have any ftfs with it. I don't want to lead anyone astray if it does not work.
I ordered two spare firing pins from Ruger just in case this did not work out on 9-6 and also ordered the parts for two magazines. The order came in the mail this morn, 9-10.Fine and fast service.
Took about two minutes to put the mags together and they cost $9.00 each this way, plus $3.50 shipping for the entire order.
Anyone ordering parts from Ruger ought to get a few spare mags this way as that is around half price from any other source I've seen.

You don't even have to look up part numbers. Just tell them which mag you need. They already have a cheat sheet with all the parts listed and will ship the parts for the mag requested.

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Post by Bullseye » Sun Sep 11, 2005 8:57 pm

Sounds good Boomer. This isn't something that has to be run all at once, doing a trend analysis over a long period of time is even better.

I was experimenting with an AR .22LR conversion unit today. My service rifle has a conversion unit that often misfires with light pin strikes. I was examining the process to see if I could get the firing pin hits stronger. I haven't come up with a solution since the problem's root cause is the Jewell trigger. That plus the rimfire converter's firing pin is off-center from where the normal AR firing pin is positioned. The AR hammer has a notch out of the top of it and this also happens to be where the converter's firing pin is located. An off center hammer strike causes a loss of energy transference to the cartridge rim and a light strike. Most of the time the cartridges fire but one out of twenty doesn't. I could make a dedicated .22 upper but I really want to see if I can make this converter more reliable, especially since I've had it so long. It does provide me with some good quality off-hand practice, but the missfires can get a little irksome.

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Post by boomer47 » Thu Sep 15, 2005 7:19 pm

Since my original post on this subject I have fired the following without a failure to fire.(give or take a few due to mis-count)
300 rounds of Win. Dynapoints.
200 rounds of Federal Lightnings(Wal-Mart bulk pack.)
150 rounds of Federal Spitfire ( probably around 10 years old).
100 rounds of CCI MiniMag.

I do see that the Dyapoints occasionly show a deeper firing pin indentation and attribute this to case setback as the Win. ammo seems to be a looser fit in MY Hunter chamber.

It has nothing to do with the firing pin shape but I did find that the old Federal Spitfire was the cleanest ammo of any of the above.
I had something like 1,500 rounds of the old truncated cone stuff that came in orange snuff can lookalikes that I had bought 10-12 years ago.
Wish I had more of them as they are accurate and clean burning.
For some reason my Hunter does not like the Minimags, they were the least accurate. The Spitfires and Dynapoints both shot dime size groups(5 each) at 25 yards off a sandbag rest using a my Simmons 2-6X scope set at 4X.
But then again, who knows? I may have been able to get through that many rounds without a misfire using the stock firing pin.
I will be honest about it though. If and when I get a ftf with my modified firing pin I'll post it.

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Post by toyfj40 » Thu Sep 15, 2005 9:05 pm

boomer: I am glad that your "test" gave some good support to your
modified-firing-pin. I have a couple extra-pins on order, this would
be my first-self-mod and I do not want to cripple my gun due to my
in-experience.

I have some 20+ year-old Federal "Hi-Power" (#810, now Game-Shok HV)
They still have the Walmart-Green-Price-Sticker on them,
(this is LONG-before BarCodes)
$2.96/100 (in a yellow plastic box, like MiniMags come in)
$3.99/100 for Federal-Game-Shock #810

30% in twenty+ years... not bad price-management by Federal
(I know I got them in 81-83 time frame).
and they are nice-clean-burning.
Good News... thanks for posting it.
Last edited by toyfj40 on Fri Sep 16, 2005 1:10 am, edited 1 time in total.
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Post by boomer47 » Thu Sep 15, 2005 11:12 pm

toyfj40, While you are at it polish the modded pin all over. Might be that I'm just too fussy but I like everything that moves in a firearm to be smooth as glass.
One polished part here and there might not make much difference but having everything slicked up will.

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