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Need clarification regarding Z1 P1 in Quickload

I'm struggling to understand what everyone is talking about in regards to Z1 and P1(Pmax) lining up properly. And from what many are saying is when they line up it's a good accurate load.
I took a screenshot of QL showing a good load for my .308. The only place I see them lining up is where they intersect each other. And I have no idea what it means.
Can someone enlighten me as to this theory by possibly showing me an example of your loads where Z1 and P1 are in alignment. The OBT is right on a node 1.133. Hope the pic is big enough to see.

Thanks all in advance
Dave





 
Be careful to look at whether the "many" who say this about creating an accurate load are many different people, or extensively repeated information from one individual. I have been researching this too, wanting to understand the issue better and 90% of what I found was repetition from one person.

That being said, I do note that Z1 and Pmax line up on many well known good loads. I'm just not sure if this is causation or correlation.

It makes sense that Z1 (the point where a powder’s progressive burn is completed and what powder remains burns digressively) would be ideally situated with Pmax since the pressure and powder burn would be in unison, so to speak. Intuitively though this seems more of an indicator that you've chosen a good powder for the caliber and desired load pressure, rather than a guarantee that the load will shoot accurately.
 
Thank you Sheldon for your input. I take any and all info that I can get on the subject of reloading.

I have narrowed down several good loads for my .223 and .308 that are accurate, but what I'm wondering is what is the graph in QL supposed to look like when Z1 and P1 line up. Line up being the key.
Can anyone draw or post an example as I have never seen what it looks like to be lined up.
I figure it will be an epiphany moment when I see the example.

Do hope that I have explained myself. I love using QL trying for OCW load by also using Chris Long's OBT theory, but came across this theory about Z1 and P1 lining up on this forum and just trying to understand it.

A picture is said to explain what is said in a thousand words..........or something to that effect.

Thanks
Dave
 
I'm struggling to understand what everyone is talking about in regards to Z1 and P1(Pmax) lining up properly. And from what many are saying is when they line up it's a good accurate load.
I took a screenshot of QL showing a good load for my .308. The only place I see them lining up is where they intersect each other. And I have no idea what it means.
Can someone enlighten me as to this theory by possibly showing me an example of your loads where Z1 and P1 are in alignment. The OBT is right on a node 1.133. Hope the pic is big enough to see.

Thanks all in advance
Dave





Dave
I can see that load will hunt. The graph show the z1 and P max are almost one line on the top of the pressure curve and your useing 16" of the barrel to get max speed your pressure is low also . Hit us back with the results.
If the load has vertical you have room to add powder an not be over pressure .
That is if your jumping the bullet.
Larry
 
Screenshot of my 87Vmax load for my 6x45AI, showing lines real close.
You can see the z1 (labeled at top) and Pmax (bottom) lines are nearly indistinguishable.

This load hammers, and projected velocity happens to be spot on...
6x45AI%20Pmax_zps4p4ugi7i.png


Coincidence? Could very well be. But, in my messin' with QL, there sure seems to be a correlation to finding a winning powder/bullet combo by paying attention to that graph.

For what its worth...
 
And here's a screenshot of my 215Hybrid load, 30-338 Norma Improved.
Same, near perfect alignment of z1 / Pmax...
30-338Norma%20Retumbo_zpslnahdw6r.jpg


This load REALLY hammers. Prolly the most consistently accurate rifle I've ever owned.
BTW, my FF load with RL-25 also shoots in the same hole. Guess what, that graph looks identical (z1 & Pmax stacked), save for it being a lower pressure load...

Note: both cases are wildcats, and my QL data has been 'tuned' specifically for each. That may have something to do my results? Just sayin', I'll keep believing what I'm seeing, cuz its happening. Coincidence, or otherwise...
 
And here's a screenshot of my 215Hybrid load, 30-338 Norma Improved.
Same, near perfect alignment of z1 / Pmax...
30-338Norma%20Retumbo_zpslnahdw6r.jpg


This load REALLY hammers. Prolly the most consistently accurate rifle I've ever owned.
BTW, my FF load with RL-25 also shoots in the same hole. Guess what, that graph looks identical (z1 & Pmax stacked), save for it being a lower pressure load...

Note: both cases are wildcats, and my QL data has been 'tuned' specifically for each. That may have something to do my results? Just sayin', I'll keep believing what I'm seeing, cuz its happening. Coincidence, or otherwise...
Haven seen it not work . Larry
 
Here's graph of my .30-338 Norma Imp. fireforming load:
Similar close relationship of z1 / Pmax...
30-338%20Norma%20FF_zpsmltlp7cw.png

Again, my data parameters are measured & logged. In the case of this FF load, case capacity used is the virgin case volume. Whereas, the above Retumbo load was computed using formed case volume...

For wildcats especially, referencing this graph in QL has made finding a load a relative non-issue!
 
OH OH OH now I understand. Yes fellas I was looking at the wrong lines. I missed it in my own graph which shows them almost touching. Now all I have to do is fine tune the load using QL to see if I can get them to come together. Wow how could I be so dumb, I just didn't see it.

Thanks to all for your answers, now I can go and play.

Dave
 
OH OH OH now I understand. Yes fellas I was looking at the wrong lines. I missed it in my own graph which shows them almost touching. Now all I have to do is fine tune the load using QL to see if I can get them to come together. Wow how could I be so dumb, I just didn't see it.

Thanks to all for your answers, now I can go and play.

Dave
Start where your at if you don't have vertical you don't have a problem . I have been using it for years with success .on your graphic you will see 95% of bullet speed I used that also . My dasher the chamber wear has decreased with my choice of powder . Larry
 
Start where your at if you don't have vertical you don't have a problem . I have been using it for years with success .on your graphic you will see 95% of bullet speed I used that also . My dasher the chamber wear has decreased with my choice of powder . Larry

What significance are you equating to using with the 95% on the graph? Please explain.

Dave
 
What significance are you equating to using with the 95% on the graph? Please explain.

Dave
See the last vertical line with 95% on it that how many of inches of the barrel is used to get 95% of the bullet speed. I feel the longer you make it The more barrel is exposed to the high pressure and heat .
Larry
 
See the last vertical line with 95% on it that how many of inches of the barrel is used to get 95% of the bullet speed. I feel the longer you make it The more barrel is exposed to the high pressure and heat .
Larry
Ok I see what you mean. Shorter length, barrel lasts longer.
TY
 
See the last vertical line with 95% on it that how many of inches of the barrel is used to get 95% of the bullet speed. I feel the longer you make it The more barrel is exposed to the high pressure and heat .

Larry, that green line is for 95% of propellant burnt not 95% of bullet speed.

The pressure and heat all happens right in that first few inches of the barrel regardless. If you model a 65k PSI Varget load and a 65k PSI H4350 load, and look at the area where the pressure falls below the -25% max pressure line, they are both almost identical and take place in the first 4 inches of bullet travel.

Your assertion that your load gets you 7 inches more barrel to spread the heat out doesn't align with what Quickload shows. The 7 inch difference is due only to the 95% burn completion line, and anything beyond the Z1 line is a regressive burn... so you're talking about basically the tail end of something that's already happened.
 
Larry, that green line is for 95% of propellant burnt not 95% of bullet speed.

The pressure and heat all happens right in that first few inches of the barrel regardless. If you model a 65k PSI Varget load and a 65k PSI H4350 load, and look at the area where the pressure falls below the -25% max pressure line, they are both almost identical and take place in the first 4 inches of bullet travel.

Your assertion that your load gets you 7 inches more barrel to spread the heat out doesn't align with what Quickload shows. The 7 inch difference is due only to the 95% burn completion line, and anything beyond the Z1 line is a regressive burn... so you're talking about basically the tail end of something that's already happened.
 
So your saying as long as the powder is burning it's not makeing pressure and heat? Larry

Powder burn is a chemical reaction. It starts with the primer, then it accelerates and burns more rapidly, then it reaches a "peak" then it starts to fizzle out and wind down. Easy to visualize, just imagine the last time you played with fireworks.

The Z1 line is the "peak" of the burn. Everything past that is the "fizzle", so to speak.

Pressure happens based on two things. One is the burn of the powder making pressure/gas, the other is the when (or time component) of that pressure and gas. The reason the when matters is that as soon as the pressure starts building the bullet starts moving. When the bullet moves the available space for the expanding gas is enlarged. Since the burn is accelerating and the bullet is also moving enlarging the space, you've got a moving target for where/when Pmax is going to occur. The longer it takes to hit Pmax the bigger the space available to do so, and as a result the more powder you can use and the more energy involved. This is precisely the reason why for a given max pressure, slower burning powders make higher velocities.

Once you are past Pmax the bullet is accelerating ever faster, the volume rapidly expands, and pressure drops as a result of the expanded volume. Simultaneously the powder, once past the Z1 line is in the "fizzle" stage and is mostly burned up already.

While Quickload doesn't draw you a line showing the percentage of powder burn, you can back into that figure by just changing the barrel length and seeing what the percentage of powder burn is. What you'll find is that 65-75% of the powder is burned in the first 4 inches, by 10 inches it's 90-95% burned, and all this burn is taking place a "digressive" manner meaning it's less energetic than the initial portion of the burn.

So essentially between 10 inches and 17 inches in the barrel, you have about 5% of the powder finishing up its "fizzle" in the lowest pressure part of the firing cycle when the pressure is falling rapidly.

All this is a bit long winded, but hopefully it helps you understand that what you've been saying isn't technically correct. Note that I don't disagree with you that H4350 is probably easier on the throat than Varget... I think that makes sense. Just not the way you've been saying it.
 

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