So how do you measure muzzle exit pressure?

The problem is the Craig Jorgensen Norwegian rifle which is also chambered for the 6.5x55, this rifle has a week action. On the other hand the swedish 96 mauser actions were all proofed at 66,000 psi, Many of these rifles were converted to 3006, 270 win 9.3x62 8x57 etc by swedish firms. I have one in the 270 Winchester, which is a 65,000 psi rifle. So bringing this rifle in 6.5x55 caliber to 60,000 psi is No big deal. The following picture shows the difference in pressure curves for slow burning vs. fast burning powders. Note both curves end at the same velocity. I uses slow burning powders to stay away from the high peak chamber pressures of the fast burning powders. This may be why published pressures show different velocities. Cup pressures are taken in or close to the chambers. Strain gauge measurements can be take anywhere along the barrel.

https://i.imgur.com/eYt5ETL.jpg

With Strain Gauge, if you've got one, I don't, but it can be done.

So why does your calculator use peak pressure, rather than the exit pressure? The truth is, the velocity is a factor of the area under the curve, not just peak pressure, or exit pressure.

Some software programs , like QuickLoad, provide peak pressure ,progressive barrel pressures and muzzle pressure.

Yes , because they take the burn rate of the powder into account. There is no place to input the power as a variable, in the calculator posted on the first page of this thread..

Wrong againElk Hunter I see nowhere in that program where it says they are using peak pressure.

S000oooo... not to hi-jack the thread... but does anyone have some 60K psi +/- 156 - 160 gr loads for a modern action swede???

Yes, I do . Do you have any RL 26 ?

So what do you suppose that 60,000psi is?

I will give you a hint. Look at the graph you posted.

https://i.imgur.com/eYt5ETL.jpg

I got to teach you everything. The pressure driving the bullet is the area under the curve, not the peak pressure. The area under both curves are equal, Hense the equal velocity.

Yet your calculation lists the pressure as 60,000psi.
Are you telling us that that 60,000 does not represent the peak chamber pressure used to estimate the velocity? So what pressure does that 60,000psi represent?

The pressure within the barrel required to drive that bullet out the muzzle at the specified velocity. Do you not know the difference between peak and Average?

If you were to measure the "area" Under the blue and red curve's they would be the same. The red line reaches peak pressure much faster then the blue one. The red line pressure spike is 60,000 psi and the blue pressure spike is 56,000 psi. The bullet in the red curve is loosing velocity while the blue one is gaining velocity (IF the test barrel was longer, chances are, the blue line bullet would have a greater velocity in the end).

Also the red line rifle would recoil at a much higher velocity and would slap the user much harder, where as the blue line would be more of a gentle push. Throat erosion would also be much higher on the red line then on the blue as well as bolt thrust and other unnecessary abuses of the action and barrel etc.

Yes, in the diagram both bullets leave the muzzle at the same speed but I know which powder I would choose.

I do understand the difference, apparently you don't. Your own statement below proves this.

If the strain gauge is placed near the muzzle , the metal that it is attached to, will never see the peak pressure, or the average pressure, it will only see the pressure remaining when the bullet passes that point in the barrel. Therefore the reading would be pretty much useless. Whether you use the copper crusher method, or the strain gauge method, the sensor needs to be placed where it will see the maximum pressure produced in the barrel, to provide the information required to produce safe loads.

X2

You Best Think that one over again. The pressure at the muzzle is the actual pressure driving the bullet. To see any dangerous chamber pressures one must observe the primer, Case head and stiffness of the bolt. This is the Time to back off, in powder, and conversation before you bring the phases of the moon into this conversation.:sHa_sarcasticlol:

The reason peak pressure is used is because it is the peak pressure that will blow up your gun. Salvee you are kind of out to lunch on your train of thought. All powders burn differently that is why they were created to boost performance of a cartrage. With your ideology we only need one type of powder all from the same lot number for every one. That is the only way we will get the same velocity with the same pressure. The case is the weakest link in a loaded and fired gun. That is usually what gives out when a gun blows up and hurts some one. A blocked barrel is a cause too but that is a whole new kettle of fish. Some powders have similar velocities but one usually takes more powder to reach the same velocity and pressure. Elkhunter11 made a good point using the Hodgson manual as the 30-06 uses a wide variety of powders.
Stob if you know some guys with Quick Load they can find you 60000 PSI loads for the 6.5x55 with various powders.

Yep, and those 60,000 psi loads will all have varying velocities depending on the powder and brass...

. there is some more "out to lunch "stuff from my post #60.

Just to let you know, the Choir is on a break right now, but thanks for the info.
Good Stuff !

Obviously you made this up.Elk is right and posted the facts to prove it, not graphs and theories

There is nothing obvious about it and there are no theories are involved,

Yes, I use a graph and other data from Quickload and a Magnetospeed chronograph to verify results. The results[ from Quickload are simply approximations, but are more accurate and consistent than guys like Elk and his "facts" will ever be. That's why they are becoming so popular.

If you guys have a problem with the real world , contact the authors of QL or any other good internal ballistic program and either prove them wrong or write your own. Chirping back and forth on an internet forum to prove a point might be fun, but it doesn't change a thing.. other than a post count. No offence intended, but I will be so bold as to suggest you and a few others obtain a good program like QL or similar, use it for a while, and report back. Fair enough ?

Actually the graph posted was correct, it actually proves that his exit pressure theory is nonsense. The graph proves that his exit pressure theory is nonsense, because while the velocity is identical, for both curves, one exit pressure is more than double the other. Of course he and the other individual with not admit that, they will try and come up some other nonsense to distract attention away from the fact that their own graph proved them wrong.

Keep it up Elk. Use any pressure you like .. It you don't like muzzle pressure, use average pressure... or stick with a manual.. as you should.

I don’t need quickload for this conversation. It’s a predictive program and we are talking about measurements. If sashi would have said that his barrel pressure was not the same meaning as the peak pressures he had referenced to start this thread nobody would have been fooled and it turns out his barrel pressure is the same thing as elks pressure curve anyway

So much for 60K
 

I was out to the range today, Looking for the start, of signs of hi pressure, in my swedish mauser 96. The first small sign of excessive pressure( primer just starting to flatten) with the 156gr bullet was at 2580 fps or about 69k psi pressure. This is 200 fps faster than factory loads. And the rifle did not blow up. Oh well it did pass the Swedish pressure test at 66K.

All I'm suggesting is using Net pressure Vs Gross (peak) Pressure... very similar to using Gross horsepower vs Net horsepower in an auto engine.Its the Horsepower that gets to the pavement that does the real work. In a firearm, I simply maintain that is the net muzzle pressure that does the real work.. (resulting velocity).. not the gross pressure. The gross pressure is just a figure that can be measured, primarily for safety reasons, as opposed to the measurable true net pressure... or average pressure, for that matter. If the gross pressure is too high, no doubt, there will be an engine or drivetrain failure somewhere along the way.The same principle goes for a firearm.

Now, for the sake of teaching me a lesson for being so stupid for even daring to mention it, will you, or Elk ,school me precisely, on what the problem is with using net muzzle pressures to consistently, and accurately, determine the resulting muzzle velocities.. I'm listening.

Salvee as I said before the peak pressure is the most important pressure. You said it your self it is a safety concern. Going over max pressure is looking for trouble or death. There are so many affordable chronographs out there use them to determine your velocity that is what they are for. Muzzle pressure will not tell you velocity any way because a 20 inch barrel with the same muzzle pressure as a 26 will not have the same velocity. I think it is time to quit beating this horse and get you a chronograph. That way you will know the acyual velocity and be guessing off of muzzle pressure and Quick Load. I like Quick Load but they even tell you their out put is an estimate not to be used as the bible for reload info.

Frankly this program is very limited in user input and therefore usefulness.
It is a far cry from the program QuickLoad is. At least you can calibrate QL with a number of specific parameters, including velocity, bullet, powder, case capacity, etc to match your loads.
In the consideration of safety I hope other reloader's don't use the OP's program for information...

Oh, I see. I'll have to get a chronograph to measure velocity ? Will a chronograph work with a 24 " barrel ?