LoaderLarry
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Thanks, will do.
QuickLOAD way off from reality. Solutions?
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LoaderLarry
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all the wayLoaderLarry
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Thanks,
LoaderLarry
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OK, will do thanks
Stammster
Well-Known Member
I have a very similar workflow as Tripodmrv7. Perhaps because I learned from his experience and posts over the years - and this method seems to give good results. (*except for our different OBT experiences). Let me reiterate or elaborate on a few points...
1.) Case length (as measured). This only seems to be important when it is used in combination with the case capacity (gr H20). Therefore only enter the value that corresponds to the case / cases that you have measured.
2.) Case capacity, in gr H20. This is where I see a lot of people doing it wrong.
a.) you should be measuring the case after it has been fired in your gun. Not after you have resized. Otherwise you are measuring the capacity of you "die chamber" and not gun chamber. I like to use the average of either 3 or 5 cases per lot.
b.) do not assume case weight and case volume correlate directly. Capacity also varies greatly by manufacture. In some cases as much as 3-5 gr H2O difference.
c.) measure to the top of the case, with as perfectly flat of water top as you can. I've heard some people say to use alcohol at xx% to remove the surface tension and get a flat top. Be aware, if this is what you are doing, and your measuring the empty and full with your scale, you are not measuring case capacity in units of water (gr H2O), but gr of that solution which has a SG less than 1. This will give you a false (low) reading. Again make sure the weight you calculate is consistent with the case length you measure.
3.) Weighting factor is also very important and previously discussed. It has to do with the shape of the bottle neck case, and essentially the weight of the unburned powder that travels down the barrel. The more the bottle neck, the more "backpressure" created and less powder is propelled. Anther way to look at this is you are in effect propelling the bullet of xx gr and powder of xx grains down the barrel, where one is know and the other is calculated by the software by tweaking this variable. Quickload has some default values, but I came across the attached file recently which was posted on the Quickload Facebook page. Someone took the time to calculate new values based on their research for both QL and GRT.
4.) Measure your bullet lengths. They don't always match the default values in QL. This influences the internal volume calculation. This is combined with the correct COAL entry.
5.) Measure your actual barrel length, not what the mfg states. Very easy with a cleaning rod, marker, and measuring tape. Close bolt and insert rod fully and measure. For example, my M70 pre-64 fwt has a mfg labeled barrel as 22", when in reality it is only 21.75".
6.) Enter the correct start pressure estimate for your type of bullet. There is a drop down menu. Keep in mind copper mono's have higher start pressure and if you neglect this input you can get in trouble as they generate higher pressure.
7.) Lastly I then shoot the load over the chrono and adjust Ba. I then make note of that Ba, at the temperature I shot it at. Sometimes it matches the default value in QL. In fact some of the more mature powders such as H4350, IMR-4064, and H4895 seem to match pretty well (1-2% max different), across different lots. Others seem to be not so good. In fact I've shot the same load with 4 different lots of RL-26, at the same approx temp, that vary quite a bit. Like 3-8% different. This makes a big difference if pushing the limit on pressure or % compressed load (i.e. from 104 to now 108%). In real life this can translate up to 1 - 1.5 grains difference for the same velocity. Interestingly never seem to find a lot of powder that is slower burn (lower Ba) than the default value. They always tend to be faster. Perhaps that has to do with the temperatures I shoot at and the fact that the temperature correction for Ba in QL seems to be sketchy at best.
In order to keep from wasting components, whenever I start a new lot of powder, I now run a powder charge ladder for a previously known load. (i.e. 51-56 gr in 0.5 grain increments). Same if I am using a new powder I've never worked with before. Plotting velocity vs charge weight, with what I already know is my calculated stopping velocity based on QL pressure estimates (i.e. don't shoot over xxxx psi). Then when I get back home I then "history match" the data and calculate the new Ba for that lot of powder.
When you compound a potential 2-3 gr H2O capacity difference, over 2-8% burn rate difference, you can see how loads can vary wildly from one another. Then throw in a temperature effect for non-temp stable powders and you can have even more error. I am a big believer in the published book data, but don't get surprised when my charge weights and velocities don't agree - even when accounting for barrel length discrepancies. In fact, I use the velocity they publish more so than the charge weights (adding or subtracting +/- 25 fps per inch barrel length difference).
Note of caution: the Ba you calculate by the above method often is the same or very similar when you change cartridges (i.e. 243 Win to 30-06), but always be cautious when doing so.
1.) Case length (as measured). This only seems to be important when it is used in combination with the case capacity (gr H20). Therefore only enter the value that corresponds to the case / cases that you have measured.
2.) Case capacity, in gr H20. This is where I see a lot of people doing it wrong.
a.) you should be measuring the case after it has been fired in your gun. Not after you have resized. Otherwise you are measuring the capacity of you "die chamber" and not gun chamber. I like to use the average of either 3 or 5 cases per lot.
b.) do not assume case weight and case volume correlate directly. Capacity also varies greatly by manufacture. In some cases as much as 3-5 gr H2O difference.
c.) measure to the top of the case, with as perfectly flat of water top as you can. I've heard some people say to use alcohol at xx% to remove the surface tension and get a flat top. Be aware, if this is what you are doing, and your measuring the empty and full with your scale, you are not measuring case capacity in units of water (gr H2O), but gr of that solution which has a SG less than 1. This will give you a false (low) reading. Again make sure the weight you calculate is consistent with the case length you measure.
3.) Weighting factor is also very important and previously discussed. It has to do with the shape of the bottle neck case, and essentially the weight of the unburned powder that travels down the barrel. The more the bottle neck, the more "backpressure" created and less powder is propelled. Anther way to look at this is you are in effect propelling the bullet of xx gr and powder of xx grains down the barrel, where one is know and the other is calculated by the software by tweaking this variable. Quickload has some default values, but I came across the attached file recently which was posted on the Quickload Facebook page. Someone took the time to calculate new values based on their research for both QL and GRT.
4.) Measure your bullet lengths. They don't always match the default values in QL. This influences the internal volume calculation. This is combined with the correct COAL entry.
5.) Measure your actual barrel length, not what the mfg states. Very easy with a cleaning rod, marker, and measuring tape. Close bolt and insert rod fully and measure. For example, my M70 pre-64 fwt has a mfg labeled barrel as 22", when in reality it is only 21.75".
6.) Enter the correct start pressure estimate for your type of bullet. There is a drop down menu. Keep in mind copper mono's have higher start pressure and if you neglect this input you can get in trouble as they generate higher pressure.
7.) Lastly I then shoot the load over the chrono and adjust Ba. I then make note of that Ba, at the temperature I shot it at. Sometimes it matches the default value in QL. In fact some of the more mature powders such as H4350, IMR-4064, and H4895 seem to match pretty well (1-2% max different), across different lots. Others seem to be not so good. In fact I've shot the same load with 4 different lots of RL-26, at the same approx temp, that vary quite a bit. Like 3-8% different. This makes a big difference if pushing the limit on pressure or % compressed load (i.e. from 104 to now 108%). In real life this can translate up to 1 - 1.5 grains difference for the same velocity. Interestingly never seem to find a lot of powder that is slower burn (lower Ba) than the default value. They always tend to be faster. Perhaps that has to do with the temperatures I shoot at and the fact that the temperature correction for Ba in QL seems to be sketchy at best.
In order to keep from wasting components, whenever I start a new lot of powder, I now run a powder charge ladder for a previously known load. (i.e. 51-56 gr in 0.5 grain increments). Same if I am using a new powder I've never worked with before. Plotting velocity vs charge weight, with what I already know is my calculated stopping velocity based on QL pressure estimates (i.e. don't shoot over xxxx psi). Then when I get back home I then "history match" the data and calculate the new Ba for that lot of powder.
When you compound a potential 2-3 gr H2O capacity difference, over 2-8% burn rate difference, you can see how loads can vary wildly from one another. Then throw in a temperature effect for non-temp stable powders and you can have even more error. I am a big believer in the published book data, but don't get surprised when my charge weights and velocities don't agree - even when accounting for barrel length discrepancies. In fact, I use the velocity they publish more so than the charge weights (adding or subtracting +/- 25 fps per inch barrel length difference).
Note of caution: the Ba you calculate by the above method often is the same or very similar when you change cartridges (i.e. 243 Win to 30-06), but always be cautious when doing so.
Last edited:
WildRose
Well-Known Member
Slight correction. Case length is very important because if your necks grow too long and get "pinched" it can cause catastrophic failures (gun blows up) due to a massive over pressure created when the bullet doesn't easily release.
That's why I'll generally check for COAL after each firing and inspect the rim to ensure I'm not seeing any engraving.
When I do trim I will trim a few thousandths shorter than SAMMI spec or in the case of my wildcats a few thousandths shy of the cartridge spec's.
Stammster
Well-Known Member
Correct what? Quickload has no idea and no modeling capability of pinched casing. My post was all about inputs for modeling accuracy and how the software uses the case length input. If you enter too long and are pinched, it wont model excess pressures.
WildRose
Well-Known Member
Ahh, you didn't specify it as a QL input, now I get it.
Zen Archery
Well-Known Member
- Joined
- Dec 27, 2012
- Messages
- 1,524
Here is another great source in explaining QL Terminology
QuickLOAD Review & User's Guide
6mmBR.com is the best guide for 6mm BR Benchrest precision shooting, complete with 6BR FAQ, Reloading Data, Shooter Message Boards, Reader Polls, and Photo Gallery. Match event calendar and rifle competition accuracy training tips. Equipment reviews (.243 bullets, 30BR cartridge, 6mm Norma...
www.6mmbr.com
