Case Head penetration test- Jeff Patterson

T

tonykharper

Well-known member
Jeff has put up two videos showing case head penetration test recently. I thought readers here would also be interested so I'm putting them here.

https://youtu.be/yBXQ2mTbreY

https://youtu.be/rbjdW6pCZb4

These tests are both for Pin Around Spring (PAS actions). The new Nitro and the Di Orio Turbo V3 action.

As many of you know Calfee and others have been doing these test for 13 years or more.

I don't think anyone has proven beyond a shadow of doubt that doing well on this test automatically means a better shooting rifle or a more accurate outcome.

But this test is another tool in the box, to judge the ignition an action is delivering. From the results decisions can be made as to pin shape, footprint sizes, springs strengths, use of spring spacers, and trigger hangar adjustment.

It is important to note these two tests were not an apples-to-apples test. One action is driving a chisel shaped firing pin and the other a crescent shaped pin. See pic below.

The crescent pin normally has a larger surface area and is therefore harder to drive.

Having done many of these tests myself I was impressed with both actions.

But from experience results like this normally goes away with time. Especially, if you use new springs for the test.

There has been more than one occasion I set ignition and within days to weeks later, found my set up was not delivering as it had done before. Then, adjustments had to be made.

Thank you, Jeff Patterson. I hope you have piqued the interest of others to do their own tests.

cresent vs chisel.jpg

TKH
 
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Also important to note the Nitro was tested as it came from Holeshot, the Turbo V3 was blueprinted by Mr. Patterson before testing.

Joe
 
65joe said:
Also important to note the Nitro was tested as it came from Holeshot, the Turbo V3 was blueprinted by Mr. Patterson before testing.

Joe
Click to expand...

Joe,

Jeff did mention he installed a full-length spring in the Nitro for the test.

According to Holeshot Arms they ship with a spring shortened two coils.

TKH
 
Question on "Consistent Ignition"

Mr. Harper,

I am an older shooter, non-gunsmith but do my own maintenance, who returned to club competition after retirement from a technical field about 3 years ago. I would appreciate elaboration on your post.

I understand the need for consistent ignition (reliably touches off round, with identical, minimal delay between trigger break and round exiting barrel) in competition shooting. I also understand bolt/firing pin fouling, firing pin wear, and spring relaxation with use over time as potentially changing ignition consistency.

However, in the relatively brief time I have been back at this game I have never noticed a perceivable change in ignition consistency (understood thus) in any of my target rifles. I have received used rifles with inconsistent ignition, that were restored to reliable ignition with bolt cleaning and/or a new spring, but have not seen any perceivable change in ignition after that. I am fortunate that my experience base runs from vintage Springfield, Winchester, & Remingtons thru modern production Anschutz, Vudoo, & Walther, to custom Falcon, Turbo, and 2500 rifles.

So my sense is that when you speak of "consistent ignition," and of having seen it degrade in a relatively short period of time, we are either talking about different things, using the same words, or you are noticing subtleties in performance that I am not attuned to. Whichever is the case, I am interested in continuously improving, and would like to learn more.

I would appreciate you taking the time to explain more about what you mean by inconsistent ignition (especially how it differs from my understanding above), what cues you are looking at to identify it occurring, its impact on grouping/scoring in top level competition, and how you address it. Thanks!

Phil Keuhlen
 
tonykharper said:
Joe,

Jeff did mention he installed a full-length spring in the Nitro for the test.

According to Holeshot Arms they ship with a spring shortened two coils.

TKH
Click to expand...

Mr. Harper

You are correct, but a spring modification is a far cry from blueprinting an entire action.
Just an observation.

Take care
Joe
 
PNW Skipper said:
Mr. Harper,

I am an older shooter, non-gunsmith but do my own maintenance, who returned to club competition after retirement from a technical field about 3 years ago. I would appreciate elaboration on your post.

I understand the need for consistent ignition (reliably touches off round, with identical, minimal delay between trigger break and round exiting barrel) in competition shooting. I also understand bolt/firing pin fouling, firing pin wear, and spring relaxation with use over time as potentially changing ignition consistency.

However, in the relatively brief time I have been back at this game I have never noticed a perceivable change in ignition consistency (understood thus) in any of my target rifles. I have received used rifles with inconsistent ignition, that were restored to reliable ignition with bolt cleaning and/or a new spring, but have not seen any perceivable change in ignition after that. I am fortunate that my experience base runs from vintage Springfield, Winchester, & Remingtons thru modern production Anschutz, Vudoo, & Walther, to custom Falcon, Turbo, and 2500 rifles.

So my sense is that when you speak of "consistent ignition," and of having seen it degrade in a relatively short period of time, we are either talking about different things, using the same words, or you are noticing subtleties in performance that I am not attuned to. Whichever is the case, I am interested in continuously improving, and would like to learn more.

I would appreciate you taking the time to explain more about what you mean by inconsistent ignition (especially how it differs from my understanding above), what cues you are looking at to identify it occurring, its impact on grouping/scoring in top level competition, and how you address it. Thanks!

Phil Keuhlen
Click to expand...

Phil,

You have asked a question that shouldn't be controversial but in today's world it is. About the only way I know to give you an answer is to ask you to recall the experience Vudoo had when they implemented the crescent shaped firing pin.

Recall they had everything from fail to fire to case head penetrations.

If you believe there is a happy medium between over driving the firing pin and setting up unwanted vibration and driving it just hard enough to achieve consistent ignition that fires every round, then you can see where this is going. If you don’t accept that theory, then save yourself a lot of trouble and not worry about it.

Said another way. There are 50-year-old rifles with the original firing pin spring that will still fire every round. At some point in time, they will get to the point it still fires every round but doesn’t create more vibration than necessary as it has done up until this point in its life. (This is the sweet spot).

Again, if you don’t think the vibration matters then don’t worry about it.

The delay you spoke of is sometimes called lock time. It matters for rifles being shot off hand, not so much for bench rifles being shot off fixed rests.

I’m sure this answer isn’t as complete as you were hoping for, but this is the best I can do without getting into a contest.

TKH
 
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Consistent Ignition - Follow Up

Tony,

Thanks for the explanation. I understand your point about vibration from firing pin fall. I ran across a discussion of it when translating a 2015 Austrian Army report on rimfire target rifle vibration testing last year. Their tests showed that the barrel vibration from the firing pin hitting an expended case was of the same order of magnitude as as those caused by the powder ignition & bullet travel. I just hadn't associated it with this topic.

Thanks for connecting the dots for me.

Phil
 
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