"High" pressure vs "Standard" pressure

[THEIS]

Hello,

So I have been talking with brass manufacturers for past couple weeks in regards to the ELR world and the upcoming wildcat chase lol.

And this question came up from RUAG......

Why do you all just not push "current" cartridges past their "limits" by ramping pressure up to get the additional MV? Is it case design you all worried about? Is it action design you all are worried about?

For example from the past...
We all know that the 408 case from Bertram was and has been tested to 80k but yet it "operates" at around 63k.
We also all know the original 408 cartridge was substantially faster than the cartridge that was released and used today. And we know that was from action design and not the brass.

So the question of pushing "current" cartridges AND some of the "wildcat" ones past what we normally utilize as pressure baseline comes back to light.....
What is our reasoning for letting pressure dictate what we do going forward....case design or action design or combination of both???

Thanks,
THEIS

 

[RockyMtnMT]

So are you saying "use a heavier action instead of trying to develop a new cartridge"?

Seems reasonable to me.

Steve

 

[J E Custom]

Hello,

So I have been talking with brass manufacturers for past couple weeks in regards to the ELR world and the upcoming wildcat chase lol.

And this question came up from RUAG......

Why do you all just not push "current" cartridges past their limits by ramping pressure up to get the additional MV? Is it case design you all worried about? Is it action design you all are worried about?

For example from the past...
We all know that the 408 case from Bertram was and has been tested to 80k but yet it "operates" at around 63k.
We also all know the original 408 cartridge was substantially faster than the cartridge that was released and used today. And we know that was from action design and not the brass.

So the question of pushing "current" cartridges AND some of the "wildcat" ones past what we normally utilize as pressure baseline comes back to light.....
What is our reasoning for letting pressure dictate what we do going forward....case design or action design or combination of both???

Thanks,
THEIS

I can only give you my take on this because of my experiences with over pressure loads.

First SAMMI sets the pressure normally based on the age of the round and the materials used. (A good example would be the 45/70. IT was designed for black powder and so were the original rifles
so when you buy Ammo for it, It is the lower pressure loading for use in the still available trap dore rifles because of its design.

Lots of modern rifle cartridges were designed for pressures less than 60,000 psi. the most recent cartridge designs have bump it up to 65,000 PSI. That is near the design capabilities of the modern rifle designs plus a 50% safety factor. also the cartridge cases are also near there maximum capabilities.

If you exceed this pressure you may get away with it but the actions will suffer and have a shorter usable life, your brass will most likely not have very good life and is more prone to failure early on.
one of the more common problems with overloads, the actions begin to increase the head space from bolt set back and at some point has to be re set.

Once I owned and shot matches with an "Overloaded cartridge and brass life was two firings at best and sometimes once. once "I" figured out that all I had to do was go to a cartridge with more case capacity, the problem went away and equipment and components lasted much longer and with little or no ware on the action. Plus an increase in velocity.

All of My wildcats are designed around a pressure of 63,000 psi and velocity is not a problem amd greatly exceeds other cartridges in the same bullet diameter and weight. all it takes is more case capacity and a few inches of longer barrel to burn the powder.

When loading "High Pressure loads" everything becomes critical and mistakes or deviation from the norm can sneak up on you and cause problems.

The simple solution is rather THAN load above SAMMI pressures use a bigger cartridge that can hold more slower burning powder and can exceed velocities without all the potential problems. so don't expect a .223 to be competitive in performance with 22/250.

Just my opinion

J E CUSTOM

 

[BallisticsGuy]

So the question of pushing "current" cartridges AND some of the "wildcat" ones past what we normally utilize as pressure baseline comes back to light.....
What is our reasoning for letting pressure dictate what we do going forward....case design or action design or combination of both???

Thanks,
THEIS

IMO, liability on the part of companies and straight up lack of necessity or economy on the part of most everyone else.

Companies have lawyers that think like this: "We've got this cartridge specification and it'll technically fit in guns that can't take the forces it can generate if someone were stupid enough to put a properly chambered barrel into an insufficiently strong action with injury or death resulting. Also, people are too stupid to regard warning labels as having useful information. So, guys, no. You can't release this cartridge with that specification. Reduce the pressures to normal levels that any modern <action type> gun could tolerate and then you can release it." Whatever argument is made by the proponents/designers about performance and intent is then moot.

From the me side, I do exactly the thing they suggest but it's plain ol' dangerous if you don't know what you're doing and when to not press your luck any further. Besides that, it just adds wear and tear.

All that aside, there's the one answer that rules them all:

 

[Pdvdh]

The brass case head is the weakest link in any modern bolt action rifle. Or the primer.

Combined, they serve notice of excessive pressures, to those shooters paying attention. Either the primer or primer pocket will typically fail before the action ruptures, or the bolt lugs shear.

Steel case heads screwed onto brass cartridges was one method to end run the weak link of brass case heads. But that fad came and went - gone. Probably due to inflated costs or for safety considerations. I don't want the first indication of excessive pressure to be the bolt thrown into my skull.

Another detriment of running higher pressures would be increased throat erosion and reduced barrel life.

Perhaps the greatest impediment to any commercial effort to ramp up operating pressures another 20,000psi would be the inability to obtain liability insurance, the high cost of attorneys fees, and ultimately - bankruptcy.

Hate to be the pessimist...

 

[THEIS]

So are you saying "use a heavier action instead of trying to develop a new cartridge"?
Steve

Hello Steve,

Yes and No
I am just opening discussion as to what others in the ELR community think in regards to "high" pressures vs "standard" pressures..specifically to the big magnum ELR cartridges; including some of the wildcats talked about on this forum.

I am saying "maybe" we haven't pushed the big bore magnums to their limits yet...For example...instead of increasing case and projectile size by going to this wildcat or that wildcat; why not put a smaller footprint, but heavier projectile into CT case and ramp up pressures the case was designed for. Now I completely understand that it would have to be done in better designed (not just bigger size) action than what the CT was built around.

The simple solution is rather THAN load above SAMMI pressures use a bigger cartridge that can hold more slower burning powder and can exceed velocities without all the potential problems. so don't expect a .223 to be competitive in performance with 22/250.
Just my opinion
J E CUSTOM

Hello J E,

The first sentence in your quote is EXACTLY the "problem" we in the ELR community are facing right now.....with going the bigger case and bigger projectile combination route; we have basically maxed "standard" pressures with pretty much the slowest propellants already.
So if the case was designed to operate at higher pressures AND the action was built for higher pressures...that would solve lots of issues IMO.

From the me side, I do exactly the thing they suggest but it's plain ol' dangerous if you don't know what you're doing and when to not press your luck any further. Besides that, it just adds wear and tear.

Hello BG,
You are correct in regards to the lawyers and such, but there are ways around that too....maybe not feasible for the individual civilian that makes a wildcat cartridge but the commercial entities have the means.

"Wear&Tear" is such a double edged sword of the ELR world..heck..of any genre shooting world. BUT with everyone wanting to push limits further and further; there comes a time where we have to chose power and velocity over efficiency. You do not have a Keith Black built hemi based on MPG. And the "consumables" of the ELR world---barrel and brass is easy to replace. As long as I have power and velocity that is accurate, reliable and repeatable....I can settle with less efficiency in order to get to where we have not been.

Perhaps the greatest impediment to any commercial effort to ramp up operating pressures another 20,000psi would be the inability to obtain liability insurance, the high cost of attorneys fees, and ultimately - bankruptcy.

Hello Phorwath,
Maybe, BUT look how long the 408CT and 375CT were out in the liability cursed world before they were CIP "accepted" and such. Yet there were no issues with insurance, attorneys and such from them.

Thanks for the early and quick discussions guys..I look forward to more.

THEIS

 

[Pdvdh]

There has to be a lawsuit before the news gets out and the lawyers circle like vultures. If and when someone is injured, and it's due to standard operating pressures off the charts compared to all normal ammunition standards..., good luck defending that injury lawsuit.

No deep pocket will go there - they stand to lose way too much $.

It'll be a shallow pocket operation that would go there in the first place. And one with an appetite for risk at that - IMO.

 

[Alan Warner]

Theis:
Strictly from a wild catters' perspective here--- I'm not about to ruin all the work and $ it takes to form up conventional brass to the specs I want just to have to replace it after one or two firings from over pressure.
Now, that said, I'd surely like to make my "brass' from titanium to better withstand higher operating pressures. Brass being the weakest link, but the easiest to form. I think the Barnard GP would run like a champ at constant pressures near 100,000 psi. That alone would translate to well over 4200 FPS. in my 375/50, maybe more.
I think I smell a research grant in the wind...


Edit --add additional thoughts

You know, brass is nothing more than an accommodation to carry loads into battle. A rifle without the use of brass at all would yield a much more consistent format --but **** inconvenient!

Alan

 

[THEIS]

Theis:
Strictly from a wild catters' perspective here--- I'm not about to ruin all the work and $ it takes to form up conventional brass to the specs I want just to have to replace it after one or two firings from over pressure.
Now, that said, I'd surely like to make my "brass' from titanium to better withstand higher operating pressures. Brass being the weakest link, but the easiest to form. I think the Barnard GP would run like a champ at constant pressures near 100,000 psi. That alone would translate to well over 4200 FPS. in my 375/50, maybe more.
I think I smell a research grant in the wind...

Alan

Hello Alan,

Yea, remember several years ago Bill Ritchie used the 2 piece tool steel case design that was meant to last forever and operate at high pressures

The Barnard GP, The RPA, A steel version of the AMSD rifle, etc would run at that high pressures like a champ too.

I think I have one of those grants lying around too.....

THEIS

 

[J E Custom]

There are other points to consider also.

There is a point that velocity will exceed the bullets design and no longer perform. (I have reached this point many times )also a bigger and stronger action and barrel only add extra weight and at some point becomes to big/heavy to be carried by most hunters and also some states have already band rifles that weigh over 16 pounds pretty much ruling out the 50 BMG, so there comes a point of diminishing returns.

I am all for improvements and the powder manufactures have stepped up and also the bullet makers. so it becomes mostly limited by the shooters ability and how far you can shoot accurately.

Having shot many long range matches it is rarely the cartridge that looses, but the shooter.

So in my opinion why push the limits beyond the human ability and risk injury with over loads.
also taking the human factor out of the equation would take a lot of the fun and skill out of it.

J E CUSTOM

 

[hemiford]

What if a company were to offer a "big/improved" action of some sort,
but advertising no perfomance (pressure) specs other than perhaps material
and thickness.

Then another company were to offer some "big/improved" brass, but
advertise no performance (pressure) specs other than perhaps material
and thickness.

Well maybe some individuals could do some experimenting, strictly for their
own personal use mind you, using the new action and the new brass
all on their own, no basis for anyone to be concerned with lawsuits..........

 

[gohring3006]

Deleted
Duplicate post.

 

[gohring3006]

It would be interesting to see if the military has noticed any effects of the Mk248 Mod
300 win mag round, noted to run at 68,000 psi up to 71,000psi.
Mainly if the barrel swells at the chamber and headspace issues.


Even though they use h1000, the hot desert would probably spike pressures.

 

[THEIS]

It would be interesting to see if the military has noticed any effects of the Mk248 Mod
300 win mag round, noted to run at 68,000 psi up to 71,000psi.
Mainly if the barrel swells at the chamber and headspace issues.


Even though they use h1000, the hot desert would probably spike pressures.

Hello,

AHHH, that was a surprise someone here brought that up
For those that have not looked at the Mk248 data yet, here you go:
http://usarmorment.com/pdf/300WM_load data.pdf

I personally do not know of any "issues" had from the military rifles. That being said I have heard of issues people having from their "custom" rifles but most of those issues are nothing out of the ordinary in terms of blowing primers, etc.

Thanks,
THEIS