A question for the ballistic scientists, err, Wildcatters.

[älg]

I´d say you have to separate efficiency from effectiveness.

An effective cartridge is one that allows you to reach the intented objective, that is, it serves its purpose. For elk hunting, an effective cartridge will be one that lets you succeed in that kind of hunt.

I´d say eficiency has to do with the ratio between the used resources and the result you reach with them ; so to compare the efficiency of two cartridges, you need to compare them based either on a common purpose/goal/result, and the one spending less resources will be the most efficient; or based on the same resources, and under same circumstances, and the most efficient will be the one giving better performance.


I am no wildcatter but in real life it is easy to see that a given cartridge will be more efficient than another one because it gives you the same performance with less powder or less resources consumption; although both can be equally effective.

[Fiftydriver]

GG,

I would agree with your comments but would also add that Rocky Gibbs and PO Ackley were not constrained to the SAAMI specs like the parent cases there wildcats were based on were.

For instance if you test a 30-06 factory loading, you will get X amount of velocity.

If you handload the 30-06 to its top potential as far as velocity potential, you will top factory loadings by as much as 200 fps. Why? the case design is the same, the answer is because we handload to higher chamber pressures then the factory ammo is loaded to.

As such, the AI rounds will offer more velocity for sure but a large part of that is due to the higher chamber pressures as well as the case design.

Ackley actually tested the 30-06 and 30-06 AI on pressure testing equipment and found that in that particular instance that the AI only produced about 40 fps more velocity when loaded to the same chamber pressure as the factory 06 loads.

So if you look at all the screaming fast wildcats or propriatory rounds out there, Weatherby, Lazzeroni or even that crazy nut that owns APS in Montana, they are getting alot of their velocity increases by adding to the top end pressure of their ammo.

Weatherby does so using freebore and large doses of powder, again not regulated by SAAMI.

Lazzeroni does this with light bullets, slow twists and special undersided coated bullets, which again allows the pressure to be used to be increased significantly compared to SAAMI regulated rounds.

My Allen Mags are no different. I design tight chambered to prevent the case stretching with high pressure loadings. I also do not have to follow any SAAMI specs and as such I can load up to just under where the primer pockets begin to loosen.

So while certainly sharper shoulders and less body taper will control powder better and keep it in the case body longer then a shallow shouldered, tapered case design, I am not sure that the increased velocity is not due to simply an increase in chamber pressure.

The first example of this I found with with my factory 22-250 Ruger VT rifle. I loaded that thing to top levels using 42.0 gr of H-380(do not use this load as it is very hot) under the 50 gr Ballistic Silvertip. This load produced 3965 fps in the 26" Ruger barrel. Primer pockets would last for three firing and were trash after that.

After I ordered in my 22-250 AI reamer for a customers project, I felt it would be great to gain another 150-200 fps over that level of performance so I rechambered the barrel to the AI and loaded up the new round to the hilt. I was supprised that when I loaded the 22-250 AI to the same level, that being getting three firings per case, The rifle only averaged 4015 fps with the 50 gr BST. So why was there not a huge velocity advantage, well, Its because I was loading the standard 22-250 to the hilt anyway.

Compared to factory loaded 22-250 specs, roughly 3600 fps with a 50 gr bullet(if that), both loadings were vastly superior to the parent factory offering but only because of increased chamber pressure.

Since then I dropped my load in that rifle to 3900 fps and case life was dramatically increased. Still with the standard 22-250 loaded to this level, case stretching would cause the cases to be discarded after 4-5 firings. With the AI design and annealing the case necks after 6 firings or so, I could get twice that many firings.

Even factory loadings like the new Hornady Light and Heavy Magnums ammo and the Federal High Energy stuff tops standard factory performance by a fair margin and often produces performance on par with the best handloads. If you look over the pressure test data of these new loadings, you see why they get better performance.

Rick Jamison(who I feel is about as biased a tester as there is) reported on just this pressure data in Shooting Times several years ago. He offered pressure data on many different standard and high energy factory loadings and right in his data he was printing that powder charge weight was often 10% heavier for the high energy ammo and that chamber pressures were anywhere from 5000 to 10000 psi heavier then standard ammo levels.

Funny thing, in his article, he stated that there was no significant increase in chamber pressure with the new high energy factory loadings yet they still produced 150 fps more velocity.

Now, 10,000 psi increase in chamber pressure is nothing to sneeze at. Thats 55,000 psi compared to 65,000 psi. In this case, top performance is a direct product of higher chamebr pressures. This is also the main reason why most wildcats produce higher velocity then their parent cases, at least to the dramatic increases in velocity.

I admit that case design plays its role but I would also say case design has more to do with case life then it does with actual FPS gained compared to a standard case design. One of Ackleys main reasons for the AI rounds was to control case stretching, with high pressure loadings.

So to me I read that as saying he loaded the parent cases up to higher pressures, realized he was getting case stretching issues and solved that problem by steepening the shoulder angle and reducing the body taper.

So, I agree with your comments but will add that chamber pressure increases are responsible for at least 50% of a wildcats increased velocity potential over its parent case design, My AMs included [img]/ubbthreads/images/graemlins/grin.gif[/img]!

There is absolutely no reason why a modern well built bolt action rifle can not handle 70,000 psi and most wildcats are loaded to very nearly this level in my opinion. You will notice that with all my AMs that I use personally, most loads are reduced from their top end levels. The reason is because I use bullets that do most of the work for me.

In my opinion, the most important aspect to a cartridges efficency is the bullet. This is the main feature in any round that will either greatly increase a rounds efficency or decrease it. By that I mean, what X grains of powder will produce down range as far as bullet velocity, bullet drop an wind drift. Case design offers little difference in this aspect where as bullet selection is critical.

This is exactly the reason why a 6mm BR loaded with a 105-115 gr VLD or ULD is a legit 1000 yard rifle whereas a 6mm-06 loaded with a 55 gr Ballistic Tip is a 600 yard rifle at very best. To that same end, a 6mm BR loaded with a 55 gr Ballistic Tip is a 400-500 yard rifle in my opinion, that same case with a 105 gr VLD is a legit 1000 yard option.

Again, when talking about a rounds efficency, we often look to the case design instead of the main factor in ballistic efficency, the bullet.

Even the most significant advances in case design efficency have very little to do with effecting ballistic efficency, even if we gain 200 fps. Its the bullet that makes the difference in my opinion.

Just my opinion on the subject, as you well know everyone has one!!

Good Shooting!!

Kirby Allen(50)

[Mysticplayer]

Guys, I have played with and designed my own series of wildcats over the last many years and have come to some observations on this topic.

Case design really does nothing for so called efficiency. Meaning - cases that have the same volume, effective bore length, assume same bore friction, similar ignition pressure curve and area (will get into this in a bit), same absolute pressure will yield the same velocity and consume the same amount of powder (assume the same load density).

But all is not equal when we compare cases, at least as promoted in a magazine.

The short fat WSM's are perceived to be more effecient but really aren't. What they have is a loading density that optimises their case volume (they use the right burn rate of powder), are run at elevated pressures, have a slightly longer effective barrel length.

Take a 300WM with the same effective bore length (we always have the assume the same bore friction), load the case to the same loading density which will use over 72grs of powder (not the 60 something many use), and launch the same bullet weight at the same max pressure and pressure curve.

The pressure curve part is critical because you can use too fast a powder, get very high pressures, but no 'push'. Use the right burn rate, lower pressures, more time 'under the curve' and go faster. Primers make a huge difference here too.

The WM will go faster. Simply a conservation of energy. More fueled burned yeilds more energy leading to more acceleration. We will assume that the barrel is long enough to show this difference (ie at least 24" long).

This has born out in all cartridges and this simple ratio works for everything, more or less.

An increase of case capacity of 10 to 12% will lead to a potential increase of 3% in muzzle velocity all else being equalized. Doesn't seem to matter what the calibre is either. Kind of neat.

This is with the type of powders we can get. There are other types that we cannot that seem to change this ratio. Will be interesting to see.

Just do a comparison to the 300WM, 300Wby, 300RUM and 30-378 when pressures are listed. The big WBY will take approx 75% more powder to go 400 to 500fps faster then the WM.

And like Kirby said, many wildcats outshoot their parent case by some really large margin NOT by case design, but by elevated pressures. The pressure of a case goes exponential (ie almost straight up) once you get at or near 60000PSI. This means that a very small increase in powder yeilds an enormous increase in pressure.

This pressure does two things - causes powders to burn better (liberate all of its energy sooner, cleaner), provide more push due to increased gas volume due to more effective powder burn.

So to try it out, and this is not a "safe" test, take a standard pressure cartridge like the 270 or 30-06 or 308. Load up using a SAAMI load. I bet brass life is excellent approaching 10 to 12 reloads no problem.

Now keep adding powder till you get brass life of only 6 to 7 firings before the primer pocket is too big. How much more powder did you use? How much faster are you going? You should be ballpark at magnum pressure levels. I bet you gained at least 100fps, closer to 150fps.

Now keep going until you get two maybe three firing before the primer falls in your lap. I bet you used just a wee bit more powder. Pressure signs everywhere and you are getting about 200 to 250fps more. I also bet your bore is pretty clean too. No sign of burnt powder.

Stick this final load on a pressure guage and you are going to need new underwear. In some cases, this will approach 80,000PSI. Some pistol wildcatters reached 100,000PSI in their quest for hand held cannons with 'no pressure signs'. This from a revolvers no less.

Isn't wildcatting fun...

Jerry

Jerry

Thanks...but NO THANKS!!

I'll leave this to the IDIOTS!! [img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]

[Fiftydriver]

The reason I feel that Wildcats are also driven to higher then standard presures is because they are generally chambered in rifles that have been properly worked over.

That meaning, the receivers are fully accurized and as perfectly square as we can make them, the locking lug recesses are lapped to at least 600 grit and at times to 800 grit.

The chambers are also polished to a very fine finish, I generally take mine to 600 grit polish.

Simply put, you can put alot more pressure in a rifle built properly and not get any pressure signs then you can with a factory rifle.

One example of this. I put together a full custom for a customer chambered in 257 STW last spring. Rem 700, Holland Laminate sporter stock, Lilja #5 27" barrel. Fully accurized of course. Sent the rifle home with the customer with load data for his specific rifle.

A couple weeks later I got a call that something was wrong with the rifle so I told him to bring it up ASAP and we would get it straightened out. When he arrived he said he was blowing promer pockets in his ammo. I was a bit puzzled by this as the top loads I had given him were totally safe and not even near loosening the primer pocket levels.

I asked him if he had changed lots of powder or anything and he said not but that he had worked my load up as it seemed very mild. Funny thing is this customer felt that sticky bolt lift was the end all of reading chamber pressure.

He said he could not understand, after firing a round he could lift the bolt with his pinky finger but the primer pocket would still be blown and was sure it was something wrong with the rifle.

Seems he had worked his load 5 full grains over what I had listed as max but it should have still been safe as bolt lift and extraction was still easy.

had that rifle been built to todays factory quality specs, the bolt would have probably needed to be pounded open with a mallet.

Point being, in a totally reworked modern rifle, pressures are very hard to predict by bolt lift or primer pocket roundness(another very poor indicator).

In a properly built rifle you will not feel any significant bolt lift increases until pressure has increased far above where it should be.

Just adding to Jerrys points which I would agree with.

Kirby
APS

[goodgrouper]

KIrby,
You make some great points as usual.
If it is ok, I would like to comment on a few. Please understand this is not jabbing you, it is merely a great thread and a great exchange of view points and ideas and is very interesting to me and other like minded crazy goof-balls.


[ QUOTE ]
Ackley actually tested the 30-06 and 30-06 AI on pressure testing equipment and found that in that particular instance that the AI only produced about 40 fps more velocity when loaded to the same chamber pressure as the factory 06 loads.


[/ QUOTE ]

So what does this tell us? It tells me loud and clear that the 30-06 already has a good expansion ratio and good efficiency and can't really gain too much of an increase in either ratio or efficiency by being improved. Incidentally, the margin of velocity increase went up when heavier than normal bullets were used.




[ QUOTE ]
screaming fast wildcats or propriatory rounds out there, Weatherby, Lazzeroni or even that crazy nut that owns APS in Montana, they are getting alot of their velocity increases by adding to the top end pressure of their ammo.


[/ QUOTE ]

Yes, agreed. And how do you get more pressure? Add more powder which decreases the expansion ratio (efficiency).




[ QUOTE ]
So while certainly sharper shoulders and less body taper will control powder better and keep it in the case body longer then a shallow shouldered, tapered case design, I am not sure that the increased velocity is not due to simply an increase in chamber pressure.


[/ QUOTE ]

This is indeed hard to distinguish because of the process of eliminating certain factors under controlled conditions.
However, in my 22-250 improved, it operates at similiar pressures that my swift did, yet the 22-250 improved pushed the vld bullet faster by a fair margin.











[ QUOTE ]
After I ordered in my 22-250 AI reamer for a customers project, I felt it would be great to gain another 150-200 fps over that level of performance so I rechambered the barrel to the AI and loaded up the new round to the hilt. I was supprised that when I loaded the 22-250 AI to the same level, that being getting three firings per case, The rifle only averaged 4015 fps with the 50 gr BST. So why was there not a huge velocity advantage, well, Its because I was loading the standard 22-250 to the hilt anyway.


[/ QUOTE ]


Agreed. This also goes back and is similair to the 30-06 scenario you mentioned earlier. Maybe the efficiency difference of the two rounds would be more apparent if heavier bullets were used.





[ QUOTE ]
I admit that case design plays its role but I would also say case design has more to do with case life then it does with actual FPS gained compared to a standard case design.

[/ QUOTE ]

I gather from this statement that you are talking about case design in regards to ackley improving a case? If so, that could be true. But if we compare a non improved case versus another non-improved case, I would say that determining a velocity increase percentage one against the other doesn't really show the efficiency of the two comparitively and if it does at all, it is indirectly. In other words, a 243 win will attain a higher velocity than a 6br, but that does not make it more efficient. Would you agree?





[ QUOTE ]
So, I agree with your comments but will add that chamber pressure increases are responsible for at least 50% of a wildcats increased velocity potential over its parent case design, My AMs included !


[/ QUOTE ]

Yes, so the chamber pressure increases come from adding more powder to the case and you add more powder to get the velocity and at the same time you decrease your expansion ratio in which you then add more powder to make up for the loss of efficiency and gain the velocity back and then...... it becomes a never ending cycle! [img]/ubbthreads/images/graemlins/crazy.gif[/img]

WHile we are here, are you saying that the reason your 7 Allen mag gets such awesome velocities over a custom, max handloaded 7 ultra is because you are loading to a higher pressure in the 7 Allen mag? Or is it because there is more powder in the 7 Allen mag? Or is it because you think the 7 Allen mag is more efficient? Or is it a combo of the three? Just curious.





[ QUOTE ]
In my opinion, the most important aspect to a cartridges efficency is the bullet. This is the main feature in any round that will either greatly increase a rounds efficency or decrease it. By that I mean, what X grains of powder will produce down range as far as bullet velocity, bullet drop an wind drift. Case design offers little difference in this aspect where as bullet selection is critical.


[/ QUOTE ]


I agree wholeheartedly with this observation. If you can launch a higher bc bullet at sufficient velocities, by all means DO IT! It will drasticly increase the <font color="red">effectiveness </font> of the cartridge. But that is really only indirectly related to the <font color="blue">efficiency </font> of the cartridge. Bullet flight deals in exterior ballistics and what happens inside the chamber deals with interior ballistics but eveyone already knows that. I just mentioned it again cause it fit in so good. [img]/ubbthreads/images/graemlins/wink.gif[/img]




[ QUOTE ]
Even the most significant advances in case design efficency have very little to do with effecting ballistic efficency, even if we gain 200 fps. Its the bullet that makes the difference in my opinion.


[/ QUOTE ]


Yes definetly. I am not too concerned with that extra 200 fps in the grand scheme of things. I would rather have a high bc bullet being flung out there at any speed. But, <u>I would be </u> concerned with that extra 200 fps <font color="red"> IF I could figure out a way to get it without USING MORE POWDER! </font> That is what efficiency is all about! [img]/ubbthreads/images/graemlins/wink.gif[/img]

[goodgrouper]

Jerry,
I must agree to disagree with you again on some of your points.

SOme are true, and some go against every known, documented stack of books on the subject known to man. [img]/ubbthreads/images/graemlins/frown.gif[/img]

Please understand I don't mean this in a negative way or anything. It's just that it doesn't quite jive.

You are basicly saying that cartridge case designers like Jim Steykl (father of the 6br) and Dr. Palmisano and Mr. Pindell (inventors of the 6ppc) and all the way up to modern guys like Kirby and his Allen mags and countless others who spent hours and hours of time stewing over case design are basicly stupid for trying to make a better and more efficient case?

I don't think so.


I am not telling you what to do, but I would suggest to you the same read I told 4ked horn about. ML Mcphersons article in the VHA will explain a lot to you.


And yes, wildcatting is fun. But only if you are a goof ball intelli-nerd like us!