Drop at 1,000 yards vs case capacity variance and +-0.1gr of powder

[jelenko]

It's just my opinion but I believe the computers use for theoretical development is interesting and useful but the process is very complicated and at this time in programming development only physical testing can achieve state of the art/technology results.

I'll go as far as to say in some cases those posting videos on computerized load development are detrimental to the loading community.

I saw a video where some guy stated that Hornady 6MM ARC load data was too hot and his program listed pressures with 3 powders. All the gas gun loads according to his computer were 15,000 to 20,000 PSI over max and bolt gun loads 10,000 to 20,000 over max.

BOLLOCKS!

Are you referring to Quickload and GRT?

 

[David Milisock]

Are you referring to Quickload and GRT?

I don't remember what program he was using but to any intelligent loader his video only suggested a problem with the program or him. It was an extremely poor video but like a train wreck I couldn't look away!

Any experienced loader knows that a company as established as Hornady would never make that huge of a mistake with 3 powders, the liability would destroy the company. There's absolutely no way a standard SAAMI AR 15 6MM ARC bolt design can handle 65,000 PSI.

But he made the video and stated that Hornadys data was wrong several times anyway.

 

[Laurie]

@David Milisock, very interesting / amusing!

Bill Alexander wrote on the 65grendel forum that QuickLOAD is inaccurate for the [6.5 Grendel] cartridge and don't use it. Contrarily, I've found it excellent, but as long as you get the fireformed case water capacity and input it - that being very different from the defaults in my case. Also, with these small cases, a change of make or even production lot, can produce a meaningful change in results and maximum charge weights - eg PPU 6.5G holds c. 1.1gn less water than Lapua fired in my rifle, and that's a lot in this size of case.

I can quite easily understand how someone without the required facts can produce complete 'BOLLOCKS' in the similar ARC, and more fool him in publicly asserting his conclusions.

I've seen people on this forum who complained when QL was as little as 10 fps out on MV on 3,000 fps predictions. When I suggested to one guy be reasonable, he told me in no uncertain terms that he was a professional engineer who used similar models in his work and he expected them to be spot-on, so he was basically rewriting half the program's values to achieve that. Good for him I thought - I worry far more about people who put acceptably good ammunition together and get in lots of trigger and wind-reading time rather than playing on keyboards, and who therefore outperform me.

QL has more than a few powders with default Ba or whatever values that are well off, and one has to to be very careful in checking results against predictions - what a good chronograph is for - especially with small case designs like the Grendel, ARC, and 6.5X47L. It's a great way for identifying potentially suitable powder options and setting starting loads, and would miss it badly in its absence. Even so, manufacturers' pressure-barrel tested loads (where available) are always going to be the gold standard, or at least the default standard to check QL's recommendations against. The problem these days is that most of us are in effect shooting 'wildcats' as for instance 223 Rem with an ISSF chamber with its 169 thou' freebore and much shallower bullet seating / increased combustion chamber volume loading 80s or heavier is a much different animal from the 223 Rem in the manuals with a short-freebore (25-thou') SAAMI spec chamber and sharper leade angle.

 

[BobbyJ]

Ever add powder and see the group print lower at 1k? It happens all the time. Thats why calculating things like this based on velocity and what should happen doesnt work. And why I cringe when people calculate how much vertical a load will have based on its es. It leaves out the most important part of tuning a rifle, barrel harmonics. How the barrel is moving can add or reduce vertical regardless of es and it can make a group print higher or lower regardless of velocity (within reason).

I think he must be assuming you are already at a harmonic node all other variables have been accounted for. This is just focusing on if those are accounted for what effect would .1 gr of powder make at 1000 yards.

Usually there is some other non accounted variable, a confounding variable that obscures this.
ie. The barrel harmonics moves the round up 10 inches but the .1 gr change only made a 1" different for a net of 9 inches.

Other things that make this .1gr moot is. What if you the shooter has a Parkinsons disease and is shaking the gun up and down 50 MOA during the shots. The .1gr of powder will be hidden because its far smaller of a error.

So I would assume that all larger errors should be accounted for first.

 

[David Milisock]

@David Milisock, very interesting / amusing!

Bill Alexander wrote on the 65grendel forum that QuickLOAD is inaccurate for the [6.5 Grendel] cartridge and don't use it. Contrarily, I've found it excellent, but as long as you get the fireformed case water capacity and input it - that being very different from the defaults in my case. Also, with these small cases, a change of make or even production lot, can produce a meaningful change in results and maximum charge weights - eg PPU 6.5G holds c. 1.1gn less water than Lapua fired in my rifle, and that's a lot in this size of case.

I can quite easily understand how someone without the required facts can produce complete 'BOLLOCKS' in the similar ARC, and more fool him in publicly asserting his conclusions.

I've seen people on this forum who complained when QL was as little as 10 fps out on MV on 3,000 fps predictions. When I suggested to one guy be reasonable, he told me in no uncertain terms that he was a professional engineer who used similar models in his work and he expected them to be spot-on, so he was basically rewriting half the program's values to achieve that. Good for him I thought - I worry far more about people who put acceptably good ammunition together and get in lots of trigger and wind-reading time rather than playing on keyboards, and who therefore outperform me.

QL has more than a few powders with default Ba or whatever values that are well off, and one has to to be very careful in checking results against predictions - what a good chronograph is for - especially with small case designs like the Grendel, ARC, and 6.5X47L. It's a great way for identifying potentially suitable powder options and setting starting loads, and would miss it badly in its absence. Even so, manufacturers' pressure-barrel tested loads (where available) are always going to be the gold standard, or at least the default standard to check QL's recommendations against. The problem these days is that most of us are in effect shooting 'wildcats' as for instance 223 Rem with an ISSF chamber with its 169 thou' freebore and much shallower bullet seating / increased combustion chamber volume loading 80s or heavier is a much different animal from the 223 Rem in the manuals with a short-freebore (25-thou') SAAMI spec chamber and sharper leade angle.

Today in the U.S. thinking is not taught in schools and apprentice programs dissappeared decades ago so I spent a great deal of time working with my children and now my grandchildren forcing them to think.

With reloading factory standard ammo I ALWAYS buy and chronograph factory ammo of the same weight I want to shoot as a baseline. I have had built a few rifles for non standard cartridges. The best example was a 450 Marlin Magnum dangerous game rifle, custom cut for 500 grain projectiles. I had a need and I was not impressed with the 458 Winchester, in my opinion too much recoil for the performance level.

The 450 Marlin is the same case capacity as a 458 x 2" and very close to the 45/70 Government. The book Cartridges of the World had old 458 x 2 loads that I could use to cross reference powders of similar burn rates, same for Siamese Mauser 45/70 loads. No computer and no 450 Marlin, 500 grain loads to work with as reference.

The thinking person realizes their mortality and does not want extreme pressure 45/70 loads that could be put into a Trap Door or a 458 x 2" that could be dropped into a 375 H&H surviving them. The custom 500 grain 450 Marlin can't be used in any other rifle due to the proprietary belt height of the case nor can it chamber in the standard lever rifles due to cartridge over all length. SAFETY FIRST!

In the end it's a decent solution, about 125 FPS slower than the 458 Winchester, less recoil, about 125 FPS faster than safe loads in a bolt 45/70, in a custom 98 Mauser.

The devil is in the details.

 

[Alex Wheeler]

I think he must be assuming you are already at a harmonic node all other variables have been accounted for. This is just focusing on if those are accounted for what effect would .1 gr of powder make at 1000 yards.

Usually there is some other non accounted variable, a confounding variable that obscures this.
ie. The barrel harmonics moves the round up 10 inches but the .1 gr change only made a 1" different for a net of 9 inches.

Other things that make this .1gr moot is. What if you the shooter has a Parkinsons disease and is shaking the gun up and down 50 MOA during the shots. The .1gr of powder will be hidden because its far smaller of a error.

So I would assume that all larger errors should be accounted for first.

It makes sense that you could determine vertical by the es, or that you could calculate poi changes by the velocity increase. But thats not how it works because your ignoring barrel harmonics that are always there and not linear. Sometimes a powder increase does nothing to poi, sometimes it jumps way up or down the paper. Depending on what side of the node your on, the harmonics will add vertical at long range or reduce it. Negative vs positive compensation. Its just not possible to calculate that stuff. You have to go out and shoot. When you see the groups not correlate to the es enough times eventually you will start caring less about chrony numbers.

 

[BobbyJ]

It makes sense that you could determine vertical by the es, or that you could calculate poi changes by the velocity increase. But thats not how it works because your ignoring barrel harmonics that are always there and not linear. Sometimes a powder increase does nothing to poi, sometimes it jumps way up or down the paper. Depending on what side of the node your on, the harmonics will add vertical at long range or reduce it. Negative vs positive compensation. Its just not possible to calculate that stuff. You have to go out and shoot. When you see the groups not correlate to the es enough times eventually you will start caring less about chrony numbers.

Im not ignoring barrel harmonics. I was saying harmonics are probably a larger issue and that .1gr will be lost as background noise. In theory if you could eliminate barrel harmonics so it does not exist then one could maybe see that .1gr change.
Adding more powder should increase velocity in the perfect world if it does not one must look at the reasons why this would be. I can think of a few reasons.

I think shooting at the extreme end of a bullets/catridges range brings out the OCD in people. I fix that by shooting closer