Good morning, with the rising cost of components I have been thinking about purchasing QuickLoad to make accurate load development easier. My question involves using the optimal barrel time charts for my specific barrel lengths can I use the Barrel time calculation and try to match the milliseconds for optimal to save some components?
Is this the information you are looking for?
Mick, Thank You. I see where this is very close to one of the listed nodes for a 26 inch barrel. Questioning is is can you try to find a barrel speed and match the “nodes” and have a decent load without a lot of development?
Thank You
This is for the load above.
Cartridge : .25-06 Rem.
Bullet : .257, 117, Sierra SPBT 1630
Useable Case Capaci: 58.936 grain H2O = 3.827 cm³
Cartridge O.A.L. L6: 3.115 inch = 79.12 mm
Barrel Length : 26.0 inch = 660.4 mm
Powder : IMR 4831
Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !
Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms
-20.0 78 40.56 2549 1688 32435 8853 97.3 1.613
-18.0 80 41.57 2607 1766 34549 9060 98.0 1.574
-16.0 82 42.59 2665 1845 36789 9253 98.6 1.537
-14.0 84 43.60 2722 1924 39162 9429 99.1 1.492
-12.0 86 44.62 2778 2005 41675 9590 99.5 1.449
-10.0 88 45.63 2834 2087 44335 9734 99.8 1.407
-08.0 90 46.64 2889 2169 47153 9859 99.9 1.367
-06.0 92 47.66 2944 2251 50136 9967 100.0 1.329
-04.0 94 48.67 2998 2335 53297 10064 100.0 1.293
-02.0 95 49.69 3051 2418 56645 10159 100.0 1.257 ! Near Maximum !
+00.0 97 50.70 3104 2502 60194 10251 100.0 1.223 ! Near Maximum !
+02.0 99 51.71 3155 2587 63957 10340 100.0 1.191 ! Near Maximum !
+04.0 101 52.73 3207 2672 67949 10427 100.0 1.159 !DANGEROUS LOAD-DO NOT USE!
+06.0 103 53.74 3258 2757 72186 10511 100.0 1.129 !DANGEROUS LOAD-DO NOT USE!
+08.0 105 54.76 3308 2843 76687 10592 100.0 1.100 !DANGEROUS LOAD-DO NOT USE!
+10.0 107 55.77 3358 2930 81471 10670 100.0 1.072 !DANGEROUS LOAD-DO NOT USE!
Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 97 50.70 3202 2663 71230 9906 100.0 1.140 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 97 50.70 2954 2267 49160 10613 99.1 1.337
Cartridge : .25-06 Rem.
Bullet : .257, 117, Sierra SPBT 1630
Useable Case Capaci: 58.936 grain H2O = 3.827 cm³
Cartridge O.A.L. L6: 3.115 inch = 79.12 mm
Barrel Length : 26.0 inch = 660.4 mm
Powder : IMR 4831
Charge : 50.7 grains = 3.29 grams
Estimates of the progress of combustion:
NR.: x(in.) Z(%) v(fps) p(psi) t (ms)
0 0.00000 1.51 0.0 3626 0.0000
1 0.00001 1.55 0.9 3713 0.0006
2 0.00003 1.59 1.8 3799 0.0022
3 0.00010 1.59 1.8 3799 0.0051
4 0.00022 1.64 3.2 3929 0.0092
5 0.00043 1.69 4.6 4058 0.0137
6 0.00077 1.77 6.4 4230 0.0189
7 0.00127 1.85 8.4 4424 0.0245
8 0.00199 1.94 10.7 4638 0.0308
9 0.00298 2.04 13.2 4873 0.0376
10 0.00429 2.16 16.2 5150 0.0451
11 0.00599 2.29 19.6 5469 0.0530
12 0.00815 2.44 23.3 5818 0.0614
13 0.01085 2.61 27.6 6218 0.0702
14 0.01417 2.80 32.3 6658 0.0795
15 0.01820 3.01 37.6 7141 0.0891
16 0.02304 3.25 43.5 7683 0.0990
17 0.02878 3.52 50.0 8277 0.1093
18 0.03553 3.81 57.2 8926 0.1198
19 0.04340 4.13 65.1 9638 0.1305
20 0.05252 4.49 73.9 10422 0.1414
21 0.06300 4.88 83.4 11268 0.1525
22 0.07498 5.31 94.0 12190 0.1638
23 0.08858 5.78 105.5 13181 0.1752
24 0.10396 6.30 118.0 14249 0.1866
25 0.12126 6.87 131.7 15396 0.1982
26 0.14063 7.49 146.5 16621 0.2098
27 0.16224 8.17 162.5 17922 0.2214
28 0.18624 8.90 179.9 19305 0.2331
29 0.21282 9.70 198.6 20761 0.2448
30 0.24214 10.56 218.7 22289 0.2565
31 0.27439 11.50 240.4 23891 0.2682
32 0.30976 12.51 263.4 25552 0.2799
33 0.34845 13.59 288.1 27277 0.2916
34 0.39065 14.76 314.4 29057 0.3033
35 0.43657 16.01 342.3 30880 0.3150
36 0.48643 17.35 371.8 32738 0.3266
37 0.54043 18.78 403.2 34632 0.3382
38 0.59882 20.30 436.1 36538 0.3498
39 0.66181 21.92 470.8 38460 0.3614
40 0.72965 23.65 507.2 40375 0.3729
41 0.80257 25.47 545.4 42284 0.3845
42 0.88082 27.41 585.2 44167 0.3960
43 0.96466 29.45 626.7 46018 0.4076
44 1.05435 31.60 670.0 47828 0.4191
45 1.15016 33.87 714.8 49587 0.4306
46 1.25235 36.25 761.3 51284 0.4421
47 1.36120 38.74 809.3 52915 0.4537
48 1.47699 41.35 858.9 54468 0.4653
49 1.60002 44.08 909.9 55939 0.4769
50 1.71026 46.50 954.3 57120 0.4867
51 1.76248 47.56 973.9 57562 0.4912
52 1.81529 48.61 993.5 57966 0.4957
53 1.86872 49.66 1013.1 58333 0.5001
54 1.92279 50.69 1032.7 58665 0.5045
55 1.97753 51.71 1052.3 58962 0.5089
56 2.03297 52.72 1071.9 59224 0.5133
57 2.08913 53.72 1091.5 59453 0.5176
58 2.14603 54.71 1111.1 59650 0.5219
59 2.20371 55.69 1130.7 59815 0.5262
60 2.26219 56.66 1150.3 59949 0.5305
61 2.32150 57.62 1169.9 60054 0.5347
62 2.38166 58.56 1189.5 60129 0.5390
63 2.44270 59.50 1209.1 60175 0.5432
64 2.47355 59.96 1218.9 60188 0.5453
65 2.48907 60.20 1223.8 60192 0.5464
66 2.50464 60.43 1228.7 60194 0.5475
67 2.51245 60.54 1231.2 60194 0.5480
68 2.52028 60.66 1233.6 60194 0.5485
69 2.58340 61.57 1253.2 60179 0.5527
70 2.64749 62.47 1272.8 60138 0.5570
71 2.71259 63.36 1292.4 60071 0.5612
72 2.77872 64.24 1312.0 59980 0.5654
73 2.84591 65.11 1331.6 59865 0.5697
74 2.91419 65.97 1351.2 59726 0.5739
75 2.98359 66.82 1370.8 59564 0.5782
76 3.05415 67.65 1390.4 59381 0.5824
77 3.12591 68.48 1410.0 59175 0.5867
78 3.19888 69.30 1429.6 58950 0.5910
79 3.27311 70.10 1449.2 58703 0.5953
80 3.34864 70.90 1468.8 58438 0.5996
81 3.42550 71.68 1488.4 58153 0.6039
82 3.50373 72.45 1508.0 57850 0.6083
83 3.58337 73.22 1527.6 57529 0.6126
84 3.66446 73.97 1547.2 57191 0.6170
85 3.74703 74.71 1566.8 56836 0.6215
86 3.83114 75.44 1586.4 56465 0.6259
87 3.91683 76.16 1606.0 56079 0.6304
88 4.00414 76.87 1625.6 55677 0.6349
89 4.09311 77.56 1645.2 55261 0.6394
90 4.18381 78.25 1664.8 54831 0.6440
91 4.27627 78.93 1684.4 54388 0.6486
92 4.37054 79.60 1704.0 53931 0.6532
93 4.46669 80.25 1723.6 53462 0.6579
94 4.56477 80.90 1743.1 52981 0.6626
95 4.66483 81.53 1762.7 52489 0.6674
96 4.76693 82.15 1782.3 51986 0.6722
97 4.87113 82.76 1801.9 51472 0.6770
98 4.97750 83.37 1821.5 50948 0.6819
99 5.08610 83.96 1841.1 50415 0.6868
100 5.19699 84.54 1860.7 49872 0.6918
101 5.31026 85.11 1880.3 49321 0.6969
102 5.42597 85.67 1899.9 48762 0.7020
103 5.54419 86.22 1919.5 48195 0.7071
104 5.66501 86.75 1939.1 47620 0.7124
105 5.78850 87.28 1958.7 47038 0.7176
106 5.91475 87.80 1978.3 46450 0.7230
107 6.04385 88.30 1997.9 45856 0.7284
108 6.17589 88.80 2017.5 45256 0.7339
109 6.31096 89.28 2037.1 44651 0.7394
110 6.44916 89.75 2056.7 44041 0.7451
111 6.59059 90.22 2076.3 43426 0.7508
112 6.73537 90.67 2095.9 42807 0.7565
113 6.88359 91.11 2115.5 42185 0.7624
114 7.03537 91.54 2135.1 41558 0.7684
115 7.19084 91.96 2154.7 40929 0.7744
116 7.35012 92.37 2174.3 40297 0.7805
117 7.51334 92.77 2193.9 39663 0.7868
118 7.68063 93.16 2213.5 39027 0.7931
119 7.85214 93.53 2233.1 38389 0.7995
120 8.02801 93.90 2252.7 37749 0.8060
121 8.20841 94.26 2272.3 37109 0.8127
122 8.39348 94.60 2291.9 36468 0.8194
123 8.58340 94.94 2311.5 35826 0.8263
124 8.77834 95.26 2331.1 35185 0.8333
125 8.97849 95.57 2350.7 34543 0.8404
126 9.18404 95.88 2370.3 33902 0.8477
127 9.39519 96.17 2389.9 33262 0.8551
128 9.61216 96.45 2409.5 32623 0.8626
129 9.83516 96.72 2429.1 31986 0.8703
130 10.06442 96.98 2448.7 31350 0.8781
131 10.30019 97.23 2468.3 30716 0.8861
132 10.54272 97.46 2487.9 30084 0.8943
133 10.79229 97.69 2507.5 29454 0.9026
134 11.04916 97.91 2527.1 28828 0.9111
135 11.31364 98.11 2546.7 28204 0.9198
136 11.58603 98.31 2566.3 27583 0.9287
137 11.86666 98.49 2585.9 26966 0.9378
138 12.15588 98.67 2605.5 26353 0.9471
139 12.45404 98.83 2625.0 25743 0.9566
140 12.76153 98.98 2644.6 25138 0.9663
141 13.07874 99.13 2664.2 24536 0.9762
142 13.40610 99.26 2683.8 23940 0.9864
143 13.74406 99.38 2703.4 23348 0.9969
144 14.09308 99.49 2723.0 22761 1.0076
145 14.45366 99.59 2742.6 22179 1.0186
146 14.82634 99.67 2762.2 21603 1.0299
147 15.21166 99.75 2781.8 21032 1.0415
148 15.61021 99.82 2801.4 20467 1.0534
149 16.02263 99.87 2821.0 19908 1.0656
150 16.44956 99.92 2840.6 19355 1.0782
151 16.89172 99.95 2860.2 18808 1.0911
152 17.34984 99.98 2879.8 18267 1.1044
153 17.82473 99.99 2899.4 17733 1.1181
154 18.19239 100.00 2914.1 17337 1.1286
155 18.67242 100.00 2932.7 16842 1.1423
156 19.15244 100.00 2950.7 16372 1.1559
157 19.63247 100.00 2968.1 15926 1.1694
158 20.11249 100.00 2984.9 15501 1.1829
159 20.59251 100.00 3001.1 15096 1.1962
160 21.07254 100.00 3016.9 14710 1.2095
161 21.55256 100.00 3032.2 14341 1.2228
162 22.03258 100.00 3047.0 13988 1.2359
163 22.51261 100.00 3061.4 13651 1.2490
164 22.99263 100.00 3075.4 13329 1.2621
165 23.47265 100.00 3089.0 13020 1.2750
166 23.95268 100.00 3102.2 12723 1.2880
167 24.00118 100.00 3103.5 12694 1.2893
Muzzle
For people who are interest in barrel timing.
http://the-long-family.com/OBT_paper.htm
Mick, Thanks that article is what spurred my question. Have you personally found accuracy by matching up the QL times with OBT ?
I've used it mostly to confirm what I've seen on the target and the chronograph is telling me. Most of my rifles have 2 piece stocks so the forarms effect the barrel harmonics so tuning is a little different than a fully floated bolt action rifle.
I think you'll find a copy of QL well be worth your time. Good luck
I've used Quickload for many years and yes, you can correlate optimum barrel time numbers with Quickload barrel times.
Remember though, Quickload isn't perfect and regardless of what internal ballistics software you might use, they all need to be tuned to your real world situation. Many people don't seem to understand that adjusting the parameters in the software to match the realities of your test results is necessary and it doesn't mean that you will create a false result, it's no different than calibrating any other kind of tool, except with Quickload you need to learn the software and some basic knowledge about internal ballistic theory in order to get reliable results.
I've used Quickload for many years and yes, you can correlate optimum barrel time numbers with Quickload barrel times.
Remember though, Quickload isn't perfect and regardless of what internal ballistics software you might use, they all need to be tuned to your real world situation. Many people don't seem to understand that adjusting the parameters in the software to match the realities of your test results is necessary and it doesn't mean that you will create a false result, it's no different than calibrating any other kind of tool, except with Quickload you need to learn the software and some basic knowledge about internal ballistic theory in order to get reliable results.
So...to get all those inputs correct, how do you isolate the effects of the Start Pressure, the Burn Rate Factor (Ba), and the Weighting Factor?
I do not believe it is possible to do it. Any one of those inputs will affect the output. You can fiddle with any of the three and get real close to agreement with your chronograph (which can be a wildcard in itself---not to mention all the environmental factors) but you'll still have no way to verify that the other parameters are correctly set.
No way you can use OBT and compare Quickload OBT without being able to measure say .1935 seconds out of your rifle.
This is the process I use to tune the software.
First things first;
What is your goal?
Are you trying to find a load that produces the perfect powder burn/pressure curve?
Are you trying to find a load that produces a specific muzzle velocity?
The end goal of every load would be to get a perfect powder burn/pressure curve along with the desired muzzle velocity which is matched up perfectly with an accuracy node while staying within SAAMI max pressure recommendations and dimensional standards and, in the case of the M1A, keeping the port pressure where it needs to be.
That's not always possible.
But that doesn't mean that you wont find a load that is as accurate as you need it to be for the kind of shooting you are doing. When you ask yourself what your goal is, keep in mind what you will be doing with that rifle/cartridge. For example, if you are planning on competing at 1000 yards then your primary goal will be to keep the bullet supersonic at 1000 yards, while keeping a desired group size, this will require that you use QuickLoad to find the right muzzle velocity and field testing the load for group size. If you simply want the tightest group at 100 yards then you will focus on the Z1/Pmax lines of the pressure/bullet travel curve and the barrel time and verify that the groups are in accordance with the standard that you set.
Next you need to understand how the data on the screen applies to the real world.
Each component (except for the primer that you choose) has it's own default data. You can change them if you need to but start with the default information.
So to start with you-
Choose the cartridge
Choose the bullet
Choose the powder
The most important thing to remember is that any data that you have actually measured should not be changed unless you have no choice. Enter all data that's been measured as it is and don't adjust it unless you have no choice or you want to do a what-if scenario.
So first you choose a cartridge, the very next thing you should do is to verify the cartridge case information.
Measure the case volume in grains of water.
You do this by writing down the weight of a fired/unsized case with the expended primer still in.
Next you fill the case with water (up to the case mouth with the surface of the water as flat as you can make it) and weigh it again.
The difference between the two weights is the amount of water, in grains, held by the case. This number gets input in to the field entitled
Maximum case capacity, overflow
I'd recommend checking at least 5 cases and averaging the water weight value. This is a value that you've actually measured so don't change it unless absolutely necessary.
Next check the case length, measure several and average the data. Put this in the field entitled
Case Length
You've actually measured this value so don't change it unless absolutely necessary.
Verify the bullet data.
Check the actual bullet length and weight, average that information after checking 5 or so bullets and enter them in to the field entitled
Bullet Length
Bullet Weight
Again, you've actually measured this information so don't change it unless absolutely necessary.
Now measure the overall length of a loaded cartridge, again average the lengths of several. Enter this data in to the field entitled
Cartridge Length
Again, you've actually measured this information so don't change it unless absolutely necessary.
Now verify the powder data.
Not much to do here right now other than to just make sure that you are using the correct powder and powder charge.
OK, now you click on the Apply&Calc button and see what your results are.
First check the Maximum Chamber Pressure (Pmax). Make sure that predicted Pmax is not over the recommended Pmax (MAP) value in the cartridge section of the screen. You should be under the SAAMI max pressure value if you've followed the recommendations of one of the commercial reloading manuals. If the pressure is too high then the first thing to adjust is the powder charge weight, reduce it to lower the pressure. From my research, I've found that the military used to use a powder charge fill ratio of about 93% to 98%, meaning that about that much of the usable volume in the case (with the bullet seated) is filled with powder. It's been a good guide for me so far so I recommend it, it's not an absolute so feel free to bend the rule if you feel you need to. Sometimes you will get fill ratios of over 100% (a compressed charge), don't worry too much about it unless the fill ratio goes over 103%, I wont use any charge that is over that limit. I know that some people push that compressed load to a lot higher value but the fact is that at some point the powder will be compressed during bullet seating but it will expand again, over time, and push the bullet out of the case. The result is the cartridge will be physically longer and it may not chamber correctly. The muzzle velocities will change too.
Now look at your muzzle velocity, compare it to the reloading manual recommendations. Sometimes you'll be off by a lot (maybe as much as 2000 FPS) and other times you'll be a lot closer. I try to get my muzzle velocities to within plus or minus 30 FPS of the book numbers. Make sure you check the book information in regards to what barrel length they used and the type of weapon. If they developed the powder charge information using a different barrel and action then you can't really expect to match their numbers very well.
Next I'll look at the pressure/ bullet travel graph. I want to see the Z1 and Pmax lines as close as possible, sometimes it just wont happen with the components you've chosen. That doesn't mean that the load wont be accurate, sometimes barrel time accuracy nodes will produce good results even when the Z1/Pmax lines don't look good. But I've found that if you can get both the graph and the barrel time to look good then my loads seem to be more reliable, it'll be one of those loads that just shoots well under a wide variety of circumstances and small variances in cartridge build specifications.
OK, so far you've worked a load up in QuickLoad using the data that you know is good but you haven't tested it yet. This is where you really need a chronograph, without it you can't verify the output of the software. It's even better if you can buy a pressure transducer system (RSI) and the chronograph. You need to run a few rounds through the chronograph and find an average muzzle velocity. Take note of the groups and record the group size and average velocity.
You should adjust the chronograph velocity for it's distance from the muzzle, technically the muzzle speed will be a little faster. This isn't imperative but if you limit every error as best as you can then you improve your chances of getting more accurate outputs. You can use QuickTarget to find the muzzle velocity. I put my chronograph 15 feet (5 yards) from the muzzle. This helps me find the true muzzle velocity.
In QuickTarget, simply adjust the Muzzle Velocity on the input data (the left window above) so that the velocity value at 5 yards is the same as the value that your chronograph showed. Now you need to adjust QuickLoad so that it produces the same muzzle velocity value. In the example above my chronograph read 2544 FPS and I had to adjust the muzzle velocity to 2555 FPS in order to get that speed at 5 yards. Now I need to return to QuickLoad and make adjustments to get it to say that my predicted muzzle velocity is 2555 FPS.
Hear is where I finally get to the important tuning stuff.
Now remember, you entered data for things that you actually measured so don't adjust any of those inputs. That only leaves a few things that you can adjust.
Powder Burning Rate Factor (Ba)
Obviously this is the burn rate of the powder
Shot Start
This is a generalization of the forces needed to engrave the bullet in to the lands (bullet friction, bullet jacket strength, primer type, bore finish, etc.)
Weighting Factor
This is a number that represents the amount of the powder charge that follows the base of the bullet as it moves down the barrel
Powder burning rate factor (Ba) is something that we can't really know for sure, so it's a prime candidate for adjustments. Powder burn rates change from lot to lot so the number used in QuickLoad will probably never be perfect. I use a limit of 0.1 when I adjust the Ba value. I don't know if that's good or bad but over time I've not had any issues using that as a limit. But I don't like to adjust just one parameter because I know that splitting an error over several factors usually limits the chances of any one factor being way off of it's true value. I try to balance the changes over the three factors I listed above. So I change the Ba value a little and then adjust the shot start value and finally the weighting factor.
Usually this gives me the ability to get the muzzle velocity I'm looking for plus or minus 30 FPS. That much error is within the margin of error of the combined errors in our process (chronograph and software errors) which usually works out pretty reliably. If you've done all that and you still can't get the muzzle velocity to where it needs to be then change the case volume. But try to spread the changes over all those variables.
So you've got the muzzle velocity matched pretty close to the real world and that means that whatever the other outputs look like, they are probably pretty close to the real world. Now you check the barrel time and the Z1/Pmax lines. If they are still off now you can change the powder charge and see if you can get them to look better, don't change anything else because you've got the software tuned to the real world as best as you can. You may find that you can't get the graph and the muzzle time to look as good as you want it, in that case it's time to try another powder and see what happens.
No way you can use OBT and compare Quickload OBT without being able to measure say .1935 seconds out of your rifle.
I don't understand what your point is.
Are you saying that you can't match the OBT to muzzle velocity?
Or are you saying that you can't prove that your rifle is producing the predicted OBT?
This is the process I use to tune the software.
First things first;
What is your goal?
Are you trying to find a load that produces the perfect powder burn/pressure curve?
Are you trying to find a load that produces a specific muzzle velocity?
The end goal of every load would be to...
You went to a lot of trouble to type all that out, and it's not unappreciated.
I have played with QL for quite a while now, and while I'd tell any handloading enthusiast it is interesting and worthwhile I would also say it is not a viable replacement for published data. It has been useful to me in some instances where there was no published data available for the combination of components I wanted to use but if a guy wants to go there you cannot possibly be too cautious.
One thing I have tried to do is determine a nearly exact Ba for a powder or three I have on hand in large quantities by using it in two or three different cartridges. If I was to luck out and come up with a Ba value that worked for a powder in multiple cartridges then I could reasonably believe that the default weighting factors and start pressures are close to real world...but such has never happened. There's too much interaction between those inputs to figure out which one is causing "what." That is the reason I poopoo the idea that you can develop and tune a load via QuickLOAD alone (and that claim HAS been made here in the past).
No matter how painstaking you are with your QL gyrations, you'll likely have to play with your powder charges a little to tweak stuff. I find it much easier to use traditional handload trials, meaning shooting groups of three to eliminate the bad loads and groups of five to find the best charge. All the calculation in the world won't take the place of that unless you know for certain the things you have to know, like a precise Ba, a precise Start Pressure, and a precise Weighting Factor...and I'm sure there are a ton of other parameters that matter.
Like I said, QL is worth having even if it's just used to play some "what if?" games. I spent many hours doing just that when I first got it, and I think I learned a few things doing that. Having used it as long as I have over the years I have seen some shortcomings with certain cartridges and that's why I will always say that it does NOT take the place of published data. The way I use it these days is simply to correlate an observed velocity with a corresponding calculated pressure, and that's simply in the interest of safety. I ALWAYS consult published data as well, if it's available. I would suggest that the most precise velocity data that can be had is highly desirable when QL is used as I do. I think the program works well enough to be in the ballpark for safety purposes (or else i wouldn't be using it as I do, obviously).
Maybe the problem of interacting variables could be solved with a software program, but I know of none.
Maybe Mathman will chime in with some ideas. He's a pretty sharp cookie.
No way you can use OBT and compare Quickload OBT without being able to measure say .1935 seconds out of your rifle.
I don't understand what your point is.
Are you saying that you can't match the OBT to muzzle velocity?
Or are you saying that you can't prove that your rifle is producing the predicted OBT?
What I am saying is you can’t maintain enough control. If you could take and load up 20 rounds where every variable was <=.001 and that you’re so perfect that your velocities are <1fps ES and 0 SD you might be able to, otherwise if you are getting say ES 30 SD 10 then your actual BT is going to differ from OBT. Now whether the difference is noticeable on target is another question. OBT doesn’t take into account the actual harmonics of individual barrels, it’s a generality which may or may not be valid.
What I am saying is you can’t maintain enough control. If you could take and load up 20 rounds where every variable was <=.001 and that you’re so perfect that your velocities are <1fps ES and 0 SD you might be able to, otherwise if you are getting say ES 30 SD 10 then your actual BT is going to differ from OBT. Now whether the difference is noticeable on target is another question. OBT doesn’t take into account the actual harmonics of individual barrels, it’s a generality which may or may not be valid.
Thanks for your clarification. I see what you are saying but I believe that you have a basic misconception of how and why OBT is useful.
I agree with your point, it is absolutely impossible to get an OBT value that will perfectly repeat itself...but that's not the point of OBT.
OBT theory says that once you get a value that is close to the optimum, the cartridge will be more tolerant of small changes in the load and the environment. We've all had that one load that just seemed to always work, and that's basically what OBT tries to identify.
I do disagree with your statement saying that OBT doesn't take in to account barrel harmonics, that's exactly what the theory is based on. The harmonics of a barrel is built in to the structure of the barrel and OBT tries to identify the best time to get the bullet to exit the muzzle, a time when the muzzle will be in a specific position relative to it's at-rest position.
As I understand the theory, it is about an annular strain that reflects back and forth from muzzle to breach, essentially a tiny bore diameter distortion that bounces back and forth. It may all be valid theory. The problem I see with it is that there are other vibration modes, such as longitudinal whip which when taken into consideration, we'd like the bullet to exit when the whip at the muzzle is at or very near an apex. Whether or not the annular vibration mode is going to harmonize with the longitudinal whip of barrel vibration is just entirely uncertain as I see it.
That line of thought has led me to wonder if there are "magic" barrel lengths that promote harmony between all the different modes of barrel vibration...but that's not something I'm ever going to try and figure out. Life is too short already and I've got a good bit of hunting to do. If the gun and load work well together, it's a GO and I'm outa here.
This is the process I use to tune the software.
First things first;
What is your goal?
Are you trying to find a load that produces the perfect powder burn/pressure curve?
Are you trying to find a load that produces a specific muzzle velocity?
The end goal of every load would be to...
You went to a lot of trouble to type all that out, and it's not unappreciated.
I have played with QL for quite a while now, and while I'd tell any handloading enthusiast it is interesting and worthwhile I would also say it is not a viable replacement for published data. It has been useful to me in some instances where there was no published data available for the combination of components I wanted to use but if a guy wants to go there you cannot possibly be too cautious.
One thing I have tried to do is determine a nearly exact Ba for a powder or three I have on hand in large quantities by using it in two or three different cartridges. If I was to luck out and come up with a Ba value that worked for a powder in multiple cartridges then I could reasonably believe that the default weighting factors and start pressures are close to real world...but such has never happened. There's too much interaction between those inputs to figure out which one is causing "what." That is the reason I poopoo the idea that you can develop and tune a load via QuickLOAD alone (and that claim HAS been made here in the past).
No matter how painstaking you are with your QL gyrations, you'll likely have to play with your powder charges a little to tweak stuff. I find it much easier to use traditional handload trials, meaning shooting groups of three to eliminate the bad loads and groups of five to find the best charge. All the calculation in the world won't take the place of that unless you know for certain the things you have to know, like a precise Ba, a precise Start Pressure, and a precise Weighting Factor...and I'm sure there are a ton of other parameters that matter.
Like I said, QL is worth having even if it's just used to play some "what if?" games. I spent many hours doing just that when I first got it, and I think I learned a few things doing that. Having used it as long as I have over the years I have seen some shortcomings with certain cartridges and that's why I will always say that it does NOT take the place of published data. The way I use it these days is simply to correlate an observed velocity with a corresponding calculated pressure, and that's simply in the interest of safety. I ALWAYS consult published data as well, if it's available. I would suggest that the most precise velocity data that can be had is highly desirable when QL is used as I do. I think the program works well enough to be in the ballpark for safety purposes (or else i wouldn't be using it as I do, obviously).
Maybe the problem of interacting variables could be solved with a software program, but I know of none.
Maybe Mathman will chime in with some ideas. He's a pretty sharp cookie.
I understand your confusion, I tried to work with Ba values too and that post I made is just a copy of post I made years ago about how to Quickload. Since that time I've changed a few steps when I'm fine tuning my Quickload estimates and the truth is that nowadays I tend to change the Ba value last. We have no ability to do a closed bomb test of the powder's burn rate, so I asked myself why would I want to question the published data that those who do have the proper test equipment, say the Ba value is. Any change we make would just be moving the Ba values randomly with absolutely no way of testing the results other than looking at your muzzle velocity values, which are never absolutely correct and in many cases are off by at least 10% or more. In the end, I just quit trying to adjust Ba values and moved on to testing the results of changing other values before I finally give up and change the Ba value.
I find that if I am meticulous about entering all the known data then I'm never off on my estimated muzzle velocities than 30 FPS or so, and that's seems like a fair tolerance value considering the tools that we have at hand. I do tend to work with the Weighting factor first nowadays and it usually helps fine tune my results more quickly.
Your claim that published material is a better choice is something that I'd recommend to any novice that has very little confidence in their skills using Quickload but you have to remember Quickload is recommended by at least one bullet manufacturer (Berger Bullets) and I'm sure others use it too.
Regardless, I agree that anybody that uses Quickload should compare their results to published manuals, I do it as a safety check. If my Quickload numbers are way off then I start reviewing what I could have done wrong and most often I find it was a mistake that I made.
In the end, do what you feel comfortable with. I know that I've been very successful at finding optimum loads without having to waste a lot of components, typically I can find a good load with no more than 50 rounds and it's not usual for me to only shoot 25 rounds and have a good sub-MOA load (at 100 yards).
Confusion my ass.
You're claiming to be able to solve problems involving three or more variables, and I am calling "BS."
Sorry if that hurts.
As I understand the theory, it is about an annular strain that reflects back and forth from muzzle to breach, essentially a tiny bore diameter distortion that bounces back and forth. It may all be valid theory. The problem I see with it is that there are other vibration modes, such as longitudinal whip which when taken into consideration, we'd like the bullet to exit when the whip at the muzzle is at or very near an apex. Whether or not the annular vibration mode is going to harmonize with the longitudinal whip of barrel vibration is just entirely uncertain as I see it.
That line of thought has led me to wonder if there are "magic" barrel lengths that promote harmony between all the different modes of barrel vibration...but that's not something I'm ever going to try and figure out. Life is too short already and I've got a good bit of hunting to do. If the gun and load work well together, it's a GO and I'm outa here.
That's what the original theory was but I've read other ballistics theory books that claim that most ballisticians don't look at harmonics quite that way. In the book "Ammunition Demystified", by Jeff Siewert, the author claims that the harmonics are pretty much controlled by the mechanical properties of the barrel steel at the time of manufacture. Siewert, and others, say that the primary frequency of the barrel is the one to be concerned with. Regardless, I have never found a really good way to find the primary frequency of my barrels so I just use the OBT theory since it estimates the same thing and it works pretty well for me.
I follow Siewert's basic guide for a good load;
"...what we're really doing is looking for a powder that burns out completely while filling the case as close to 100% loading density as possible without exceeding the allowable pressure. Not coincidently, this propellent solution usually provides pretty close to the highest muzzle velocity that can be attained with the particular projectile-cartridge case combination."
With Quickload, I can create a list of powders that will match those parameters (100% fill, 100% burn in the barrel, and max pressure) and export it in to a spreadsheet, which allows me to filter the results down to one or two powder combinations very quickly.
I'm not trying to sell anybody on the idea of using Quickload, I'm just stating how I've been successful in using the software and why I use it the way I do.