Tension Testing - It is official!!! According to Instron there is such a thing as tension testing

[Webster]

Instron is one of the leading tensile testing machine manufacturers on the planet.
They make a living building machines that are used for every day tension tests in engineering and quality labs.
Perhaps our members that do not believe there is any such thing should read the introductory page for tension testing at the Instron home page. The Instron logo consists of 2 stylized stick figures pulling a piece of test material.

Tensile Testing

What is Tensile Testing?
A tensile test, also known as tension test, is probably the most fundamental type of mechanical test you can perform on material. Tensile tests are simple, relatively inexpensive, and fully standardized. By pulling on something, you will very quickly determine how the material will react to forces being applied in tension. As the material is being pulled, you will find its strength along with how much it will elongate

http://www.instron.us/en-us/our-company/library/test-types/tensile-test

I ran an INSTRON TENSILE TESTER at LTV STEEL for about ten years. Measuring tension pulling in a straight line has nothing to do with what's called hoop tension. GOOGLE hoop tension.

 

[KMart]

I bet you don't know what you are talking about because you have never been an engineer and you have never brought a product on line. Anyone that has been an engineer would not make such a general statement. Furthermore you apparently don't understand that marketing and management dictate many of the constraints that limit manpower, budget, research and testing of a new design. You are blaming engineers for the cost cutting goals that come from management's desire to make a bigger performance bonus.
For example many automotive engines do well to last 150,000 miles when a diesel truck engine can easily last much longer. The ability to make a very long lasting engines had been around for more than 50 years. It is not the fault of the engineers if management wants to sell engines with a limited oil sump capacity just to cut down on the number of quarts of oil that roll out the door in the crankcase.
On top of that you apparently cannot tell the difference between design issues and manufacturing defects. Often they appear to be one and the same. Without conducting failure analysis you may not know. I have seem many surgical instruments fail due to incorrect materials and heat treat. I have also seen many that failed because the surgeons beat them to death.
Sometimes stupid customers don't take care of and maintain their car properly. One of my high school acquaintances blew up his 375 Hp 396 Chevelle engine drag racing it - twice. He got 2 new short blocks installed under warranty. Do you really think poor engineering caused that?

I know exactly what I am talking about. I worked in the chemical industry for 35 years and manufactured things like hydrazine hydrate, maleic anhydride, polycarbonate plastic, bisphenol-a and a few other things.
I started up and operated 4 units from dirt to product out the back door. I worked with and for mechanical, electrical, environmental and chemical engineers every day of those 35 years. Yes, I know EXACTLY what I am talking about.
They would tell us to run things exactly the way they designed it to and all would be good. They didn't have a clue. We were left to our own devices to find a way to make it work.
Once the design and installation was done, they left on vacation and was absolutely no help. It was probably better that they were gone because they would have only slowed down the recovery process had they stayed.

 

[BoydAllen]

How come military members win matches with their military handloads and rifles they rebuilt setting records in competition with civilians and their stuff in local, national and international events? Lt. Gary Anderson used military produced ammo from the Army's AMU to win gold in Olympic 300 meter free rifle matches with hollow point bullets they had Sierra make for them.

All you "stiff receiver" afficianados need to know in the 50's, the US Army AMU had Winchester make 20 Model 70 receivers without a magazine cutout; heavy and solid bottom single shot ones for long range match rifles. They shot their handloads as good as any rifle today.

Some shot their way onto the US Palma Team with military rebuilt bolt rifles (and some shooting 7.62 Garands) with their shops hand loaded ammo.

Bring any prone or position equipment and ammunition to a benchrest match. I have the greatest respect for the skills of those shooters, but I was referring to the ultimate in accuracy, and no one can reach that level holding a rifle in his hands, but they can demonstrate insane levels of skill.

 

[Bart B.]

have the greatest respect for the skills of those shooters, but I was referring to the ultimate in accuracy, and no one can reach that level holding a rifle in his hands, but they can demonstrate insane levels of skill.

Neither can a stool shooter holding their rifles in their hands, no artificial support whatsoever, shoot the scores bullseye folks do with their rifles.

Accuracy tests of NRA bullseye matchrifles and ammo shot held against ones shoulder in 3 position matches but clamped in machine rests prove they're as ultimately accurate as the ones benchrest ones are. Otherwise, they wouldn't do as well as their scores show.

Has any benchrest rifle shot 6 to 7 dozen consecutive 10-shot groups at 600 yards all under 1.5 inch like an old pre-'64 Win 70 based 3-position NRA high power match rifle has?

 

[dmoran]

Neither can a stool shooter holding their rifles in their hands, no artificial support whatsoever, shoot the scores bullseye folks do with their rifles.

Accuracy tests of NRA bullseye matchrifles and ammo shot held against ones shoulder in 3 position matches but clamped in machine rests prove they're as ultimately accurate as the ones benchrest ones are. Otherwise, they wouldn't do as well as their scores show.

Has any benchrest rifle shot 6 to 7 dozen consecutive 10-shot groups at 600 yards all under 1.5 inch like an old pre-'64 Win 70 based 3-position NRA high power match rifle has?

Would like to see all the specifics of that claim:

1. Results
2. Targets
3. Place(s)
4. Date(s)
5. Conditions
6. Test criteria's

Thanks

 

[BoydAllen]

Evidently you did not notice when the F Class targets scoring rings were reduced to half the size of those used by prone shooters. The reason was that it had become obvious that they were too easy given the advantages of shooting off of rests with high magnification scopes. As far as your claims for match rifle accuracy go, I would probably have to see not only the original documentation, but also see it done. Yes I am skeptical. Finally, as a general principle I measure accuracy by what is able to be done out of the lab, in the real world as it were. Shooters who carry on about the superiority of old style prone rifles have probably not shot many sanctioned benchrest matches, or if they have lack recent experience. Those that currently compete are free to shoot any equipment and ammunition that falls within the scope of the rules. I am sure that some match directors could be persuaded to allow testing of unusual equipment during an actual match. Perhaps someone will be willing to demonstrate their equipment's superiority.

 

[Mulligan]

Neither can a stool shooter holding their rifles in their hands, no artificial support whatsoever, shoot the scores bullseye folks do with their rifles.

Accuracy tests of NRA bullseye matchrifles and ammo shot held against ones shoulder in 3 position matches but clamped in machine rests prove they're as ultimately accurate as the ones benchrest ones are. Otherwise, they wouldn't do as well as their scores show.

Has any benchrest rifle shot 6 to 7 dozen consecutive 10-shot groups at 600 yards all under 1.5 inch like an old pre-'64 Win 70 based 3-position NRA high power match rifle has?

Not to be contrary, just asking.
Are you really suggesting, one person and one rifle shot 72-84 consecutive 10 shot groups at 600 yards and every one of those 10 shot groups were under 1.5"?
CW

 

[Bart B.]

Would like to see all the specifics of that claim.

1. Results; several 10-shot groups ranging from about 1.5 inch down to about 0.7. One 40-shot group into 1.92". Don't know the exact group count but it was over fifteen 10-shot groups, as I remember.
2. Targets; paper on a high power range target carrier. One 10-shot group was shown in a Lapua bullets ad in a fall, 1971 issue of the American Rifleman
3. Place(s); some canyon near Long Beach, California.
4. Date(s)' early 1971
5. Conditions; calm. Rifle clamped in a machine rest identical to this one belonging to David Tubb showing one of his T2000 rifles in it. David's Dad, George, had it built in the early 1960's along with a dozen or so other top ranked NRA match rifle competitors. Load: Lapua D46 .3092" 185-gr FMJRB match bullets. 42 gr. IMR4064, WCC58 match fulll length sized cases, primer not known:
6. Test criteria's; reason was to see how perfectly balance bullets shot.

That rifle and ammo won all the 600-yard matches at the 1971 NRA High Power Nationals.

Do you want to know who shot all those tiny groups?

 

[dmoran]

@Bart B.
To bad you don't have the actual pictures, resultants, targets, etc. to go with your claim.
Sorry, but will remain skeptical until I see actual.
Thanks any how.

 

[Bart B.]

72-84 consecutive 10 shot groups at 600

No, I erred a bit. Thanks for getting my attention. I've no idea why I plugged in "dozen" when it was not right at all.

There were about eight to ten 10-shot groups, then 3 dozen plus 4 extra were included in the 40-shot string mentioned; 40 more rounds. That was a long time ago.

 

[dmoran]

No. 6 to 7 dozen, as I remember 3 dozen plus 4 extra were included in the 40-shot string mentioned.

What gives?

6 to 7 dozen consecutive 10-shot groups at 600 yards all under 1.5 inch like an old pre-'64 Win 70 based 3-position NRA high power match rifle

 

[dmoran]

No, I erred a bit. Thanks for getting my attention.

There were about eight to ten 10-shot groups, then 3 dozen plus 4 extra were included in the 40-shot string mentioned; 40 more rounds. That was a long time ago.

One heck of a claim to reply with, if not sure of all the specifics any more or have the actual results.
Agree, that is a long time ago... I was 6... lol

 

[Webster]

My concern with tension is uniformity. If I were to pull a bullet using an applied tension, for example using a collet type bullet puller, I would expect to see a curve if I plot it. There will be a breakaway tension being the force needed to start the bullet dragging out of the case mouth followed by the force required to continue to drag the bullet out of the case mouth. If I did this using a constant force applied uniformly what I figure I want to see is uniformity from cartridge to cartridge. I have given some thought to doing this but never managed to build a test fixture.

Ron

Yes it could be done but not practical. We don't own tensile testers. The tester pulls at a constant rate (distance of movement). The plot would be pounds force vs time or extension. I always believed if you cannot see the difference on the target it doesn't matter. The results would probably open a big can of worms.

 

[BoydAllen]

You are making a very erroneous assumption.
You could probably pull test a sample of military ammo and find a correlation between the value of the bullet pull, accuracy and accuracy.
Just because you want to look down your nose at military ammo does not mean that it is not affected by bullet pull variations.

Reread what I wrote. I said nothing about what you objected to. I did not say that there was no correlation, or that I look down my nose at military ammo. I will say this. None of it will win a benchrest match, on the other hand I would never take a tight neck chambered benchrest rifle into battle. Going back to what you originally wrote I believe that you extrapolated from the military data, that less bullet pull produces more uniform results. That is the part that I was addressing, and I gave a couple of examples. Again using data that was developed by testing for an entirely different application may lead one astray.

 

[BoydAllen]

A little clarification: Nowhere have I diminished the value of engineers. What I have said is that their skills are not universal, and they may be prone to forgetting that. Neither have I denigrated the use of statistics, or advanced project management systems. My purpose was to point out that people who have more engineering experience than shooting experience often do not know what they do not know about shooting, however brilliant and indispensable they may be in their own fields of expertise. What we are doing is literally not rocket science. Reading some responses I sometimes get the feeling that some who have spent their lives successfully dealing with complicated problems may try to import those methods into an arena that in nowhere near as complicated, and in the process create more confusion than clarity. When I spoke of unlimited resources, I was speaking in relative rather than absolute terms. I would have thought that to be obvious.

 

[Alex Wheeler]

I agree with Boyd. Some of the best guys in this game are engineers. Jim Borden for example, not much he has not done and doesnt understand. But the point is, unless you are an engineer that is specializing in tension and how it effects ammunition then your findings in another field just dont matter. Prime example, we all know that brass will only stretch so much before it yields. After this yield point all amounts of neck tension should be equal. Thats not how it works in the real world though. Plus this is getting over complicated. All the guys I know that hold world records, just go out and try different neck tension and use what groups the best. It really is that simple.

 

[snert]

A little clarification: Nowhere have I diminished the value of engineers. What I have said is that their skills are not universal, and they may be prone to forgetting that. Neither have I denigrated the use of statistics, or advanced project management systems. My purpose was to point out that people who have more engineering experience than shooting experience often do not know what they do not know about shooting, however brilliant and indispensable they may be in their own fields of expertise. What we are doing is literally not rocket science. Reading some responses I sometimes get the feeling that some who have spent their lives successfully dealing with complicated problems may try to import those methods into an arena that in nowhere near as complicated, and in the process create more confusion than clarity. When I spoke of unlimited resources, I was speaking in relative rather than absolute terms. I would have thought that to be obvious.

Out of this whole thread, I think this statement makes the most sense. And is the most humble.

Sometimes we just don't know what we don't know. Goes for engineers and bakers and shooters and philosophers. Especially Philosophical engineers who are baking and shooting out an opinion...

 

[mikecr]

Someone mentioned hoop tension, and someone else referenced SAAMI to describe it:
NECK TENSION
The circumferential stress that the case neck exerts on the seated bullet, as a result of the interference fit provided by the case neck inside diameter and the bullet outside diameter.

This is not 'bullet pull', as the definition dismisses friction. And the 'stress' in this definition is spring back force against the bullet (grip).
It is easy for anyone here to test and see that 'pull force' is not directly meaning anything about your actual tension.
Take 10 case necks to squeaky clean. Take 5 bullets to squeaky clean, and coat 5 with anything slippery except moly.
Seat, with great effort, the 5 clean bullets to target CBTO. Seat the 5 lubed bullets, with way less effort, to same CBTO.
Fire them across a good chrony, you'll see no difference in MV. Well, Bart you can go ahead and do this 100 more shots to believe it..

Now outside an extreme pressure node, we all know neck tension variance affects MV.
To see this, adjust it, and test it, think hoop tension & grip instead of pull force. Vary a spring back area to bullet bearing area and watch what happens to MV. Now we're talking about tension, and we currently have no direct way to measure it, given that we have no way to measure spring back force.
It could be done, but I've yet to see it.

 

[BoydAllen]

If muzzle velocity was the only consideration then we could simply do things to make that more uniform and be done with tuning. Of course it is not. One of the three principle ways that we tune is with with bushing size, all sizing the same amount of the neck. It shows up on the paper which trumps the chronograph. I think that it may be because of the time to muzzle issue.

 

[dkhunt14]

If muzzle velocity was the only consideration then we could simply do things to make that more uniform and be done with tuning. Of course it is not. One of the three principle ways that we tune is with with bushing size, all sizing the same amount of the neck. It shows up on the paper which trumps the chronograph. I think that it may be because of the time to muzzle issue.

I thought it had more to do with holding the bullet a little longer. Maybe slightly more pressure and a better burn or more consistent releases. Matt