It's a simulation program! If you ever used any type of simulation programs, first thing you learn is to calibrate for each given case. Ba used in one case is a starting point for the next. It's like taking a load for one rifle and using it in another. Works well enough for short range. Have to adjust for longer
QL and why or GRT
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Michael Lares
Well-Known Member
As with all computer programs, it's always garbage in = garbage out.
Been using QL for years with great success. Now, having said that, have to say I fought loads for some calipers over & over trying adjusting BA etc. etc. So:
some of the inputs that have to be exact to get exact results,
Actual measured volume of fired case from specific chamber
correct starting psi for given bullet @ bullet jump used
correct weighting factor for a given cartridge.
After realizing these facts things fell in place way better. I hardly ever even adjust BA anymore. If I do, it's usually on something I know nothing about. On a cartridge in that category, I will start with a book load using like Nosler book only because they offer case volumes and oal for the specific load. I will sometimes have to adjust BA to make book load work on QL. I sometimes will use that BA for that powder / bullet weight / barrel length to establish a baseline to begin with.
The problem I have found in QL adjusting Ba is that yes you can tweak in the Ba for that EXACT load, grains, etc but I've had little to no success ONLY adjusting Ba and getting it to match velocities say across a 10 round ladder.
I normally will adjust Ba, progressive burn rate and the case factoring percentage. It takes some time to figure out which to adjust and how much and only you can determine if that's worth your time.
I normally will adjust Ba, progressive burn rate and the case factoring percentage. It takes some time to figure out which to adjust and how much and only you can determine if that's worth your time.
RegionRat
Well-Known Member
The issues folks are having are not difficult to explain, but that said they are difficult to solve.
There are several other issues with matching results that are not as popular to discuss. It is easy to grab an accurate muzzle velocity but how many folks can (calibrate and) measure pressure?
Clearly the BA and energy from the powder charge is important, but the energy of the primer, energy lost to the case/chamber fit, energy lost due to brass prep, combustion pressure effects of jump and bullet engraving, bullet friction, etc, etc,. are also significant parts of the system.
Many folks take this on with the idea that they can use one or two levers to fit the model to their data, but then try to extrapolate parts of their model to a different recipe or even to a different gun, and they try this without actual pressure data. The models can swallow some composite errors where it comes to friction losses, but not knowing the actual pressure is a handicap if you then try to extrapolate using the models.
With those concepts in mind, it shouldn't be a surprise that the odds of a perfect match to all those other parameters coming from the defaults in the software, versus your results, probably won't be perfect even when you have decent input for most of them since it is rare to have all of them.
That is not to be taken as a condemnation of the programs or those efforts versus their value. Even without pressure and other measurement inputs, you can learn a lot from practicing with these models.
The research, measurements, and experience required to just run a "standard" scenario is not bad. However, the experience required to actually predict pressure and match results when jumping to say a wildcat prototype is another matter. In my opinion a person will need to study and practice with many different "standard" load cases, calibers, and rifle systems before they get to where they can extrapolate well with big changes, unusual cases, or wildcats. YMMV
There are several other issues with matching results that are not as popular to discuss. It is easy to grab an accurate muzzle velocity but how many folks can (calibrate and) measure pressure?
Clearly the BA and energy from the powder charge is important, but the energy of the primer, energy lost to the case/chamber fit, energy lost due to brass prep, combustion pressure effects of jump and bullet engraving, bullet friction, etc, etc,. are also significant parts of the system.
Many folks take this on with the idea that they can use one or two levers to fit the model to their data, but then try to extrapolate parts of their model to a different recipe or even to a different gun, and they try this without actual pressure data. The models can swallow some composite errors where it comes to friction losses, but not knowing the actual pressure is a handicap if you then try to extrapolate using the models.
With those concepts in mind, it shouldn't be a surprise that the odds of a perfect match to all those other parameters coming from the defaults in the software, versus your results, probably won't be perfect even when you have decent input for most of them since it is rare to have all of them.
That is not to be taken as a condemnation of the programs or those efforts versus their value. Even without pressure and other measurement inputs, you can learn a lot from practicing with these models.
The research, measurements, and experience required to just run a "standard" scenario is not bad. However, the experience required to actually predict pressure and match results when jumping to say a wildcat prototype is another matter. In my opinion a person will need to study and practice with many different "standard" load cases, calibers, and rifle systems before they get to where they can extrapolate well with big changes, unusual cases, or wildcats. YMMV
That's part of the "why and how" should you use or change that input on which primer is being used?
Dancin' Crosshairs
Active Member
Primers have nothing to do with it.
My main concern on development is pressure! The output/results on fps and energy are of less concern. I've used (based on published load data from various mfgs that list fill %) info and input said data then it's a wild projection of what was listed. Say, 108% will produce 20k over pressure on said published data. Even using their starting load (according to QL) can be over pressure. I'm just glad I haven't found out the hard way and gun went kaboom on me by using published data. ONLY 1 time I've used a data result from QL on a pistol load (357sig). I was fortunate with results! I do cross check my input on QL against published info for referencing. And they say that Nosler uses QL for data seems crazy, especially when their data and the QL I have aren't even close on pressure! I guess they did some tweaking on their end before publishing.
Why would you think that! Not all are created equal, let alone burn temp, burn length and burn amount!
I find it interesting how discussions go about any time ANY software is discussed. This is the last comment I eill make on QL and GRT.
First, let me explian something, I am an egnineer, not a scientist. I say that because there is a huge difference. The first is looking for a perfect solution, and the second for a "good enough" solution for the application. I know a few engineers on this forum might get upset with that now.
I have spend all my life using and calibrating software to do very explex modelling. Over 1000 variables of which we could know maybe 10-20. And yet we succeed. The same with QL and GRT. There are so many variables in the internal ballistics, yet we only know a few with certainty. Thus we end up lumbing up a few, using "defaults" and averages.
I have used QL effectively to get an idea where my "load" should be, and then fine tune with shooting results. I also, after the fact, checked what I had developed as good loads before QL and before a chrony, and matched the results well.
GRT offers you a couple of otions more than QL and I hope the people taking over continue development, especially adding new powders and projectiles. I can "estimate" your Ba and "friction" and suggest a load for you. But its up to the user to validate.
I am getting ready to do a new load development on 338 LM. I have an idea what is max in MY rifle for the poejectile and powder. I know the "fired case" volum in my rifle.
I will shoot two sets of 5 rounds. Record velocities, temperature. Get to sets in GRT to suggest new load using OBT. Then I will try the new loads, and adjust as necessary,
Statisticians will say, not enough data. For my purpose, a hunter, not a competitive shooter, is enough.
In my 40 years of working with various computer models I have never found a "perfect" nor I expect to find one. The idea is to use a model, QL, GRT, something else, to fine tune your load and rifle. I don't suggest this for anyone else. QL worked good enough for me in the past. OCW worked, Ladder method worked and I expect GRT will ork better than any of those.
My suggestions, use what works for YOU! Share, some people will use your experience to better theirs, some will criticise it.
Cheers!
First, let me explian something, I am an egnineer, not a scientist. I say that because there is a huge difference. The first is looking for a perfect solution, and the second for a "good enough" solution for the application. I know a few engineers on this forum might get upset with that now.
I have spend all my life using and calibrating software to do very explex modelling. Over 1000 variables of which we could know maybe 10-20. And yet we succeed. The same with QL and GRT. There are so many variables in the internal ballistics, yet we only know a few with certainty. Thus we end up lumbing up a few, using "defaults" and averages.
I have used QL effectively to get an idea where my "load" should be, and then fine tune with shooting results. I also, after the fact, checked what I had developed as good loads before QL and before a chrony, and matched the results well.
GRT offers you a couple of otions more than QL and I hope the people taking over continue development, especially adding new powders and projectiles. I can "estimate" your Ba and "friction" and suggest a load for you. But its up to the user to validate.
I am getting ready to do a new load development on 338 LM. I have an idea what is max in MY rifle for the poejectile and powder. I know the "fired case" volum in my rifle.
I will shoot two sets of 5 rounds. Record velocities, temperature. Get to sets in GRT to suggest new load using OBT. Then I will try the new loads, and adjust as necessary,
Statisticians will say, not enough data. For my purpose, a hunter, not a competitive shooter, is enough.
In my 40 years of working with various computer models I have never found a "perfect" nor I expect to find one. The idea is to use a model, QL, GRT, something else, to fine tune your load and rifle. I don't suggest this for anyone else. QL worked good enough for me in the past. OCW worked, Ladder method worked and I expect GRT will ork better than any of those.
My suggestions, use what works for YOU! Share, some people will use your experience to better theirs, some will criticise it.
Cheers!
Dancin' Crosshairs
Active Member
Are you here just to have stupid arguments? Or do you know how to account for primer differences when setting up GRT or QL to compute a solution? Or have you ever even actually used any of the software???
They say that computers aren't dumb, only the 1's that program them! Then again, I haven't seen the person who 1st stated that also! No telling what he/she was! I do realize the complexity of programming as I've worked on both sides of it! Most of the time I was working on other peoples to fix their mistakes or what was overlooked.
I'm horrible on using GRT, but do have QL. So yes I do have the software installed and updated. You do realize when you are pointing that finger at me, you are having 3 pointed back at you! So your stupid argument with yourself is
Dancin' Crosshairs
Active Member
Wow. I may hang out here more often just to follow you around for a laugh.
Please do tell me how to account for primer variations in QL, Professor Douche.
Please do tell me how to account for primer variations in QL, Professor Douche.
Dancin' Crosshairs
Active Member
Please, just one more belly laugh before I head for la cama. Makes me sleep like a baby!
LOL.
LOL.
