Quickload question 5.56 help settle an argument

Polaris · Jan 2, 2018

Trying to settle an argument with some fellow high power shooters. 2 guys strictly throw their powder charges, and contend that +/- .1 grain of accuracy in powder charge will not affect practical accuracy for this game.

Here's the scenario I'd like to run. Barrel length 20", twist 1:8, Nosler 77bthp (or similar if that one isn't available), primer Fed Small Rifle match, powder Varget. Charges 23.9, 24, and 24.1. I'll run the velocity numbers and see what the impact deviations would be at 200, 300 and 600 yards in terms of elevation and wind call for a full value 10mph.

Looking for predicted velocity, pressure might be interesting also.

salmonchaser · Jan 2, 2018

I know a retired SPD officer who happens to be one of the top Palma shooters in the country. Many years ago I packed my reloading equipment to the range to work on load development. I was being very meticulous. He told me he uses powders that meter well and is quite content with +-.1 grain. Once he has established his load.
He explained, I think I understood, that the shot to shot standard deviation will put most of those rounds in the middle of the bell curve. He also said you have to stay within the .1 window.
I think with your study unless you use a random number generator to account for shot to shot deviation you won't get an accurate picture of what happens over say 1000 rounds.

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Polaris · Jan 2, 2018

salmonchaser":2981pq88 said:
I know a retired SPD officer who happens to be one of the top Palma shooters in the country. Many years ago I packed my reloading equipment to the range to work on load development. I was being very meticulous. He told me he uses powders that meter well and is quite content with +-.1 grain. Once he has established his load.
He explained, I think I understood, that the shot to shot standard deviation will put most of those rounds in the middle of the bell curve. He also said you have to stay within the .1 window.
I think with your study unless you use a random number generator to account for shot to shot deviation you won't get an accurate picture of what happens over say 1000 rounds.

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I'm looking for maximum potential deviation, not average, so see if .1 grain high or low with a 5.56 charge (vs a nearly doubled Palma charge) would potentially drop some X's or points at the 200 and 300 mark, in a game that is often decided by a single X or point.

pharmseller · Jan 2, 2018

What's the margin of error of your scale?

P

thatguySHM · Jan 2, 2018

This is why flat spot load development is important. If you get .3-.5 grains where it's pretty flat in your rifle, then the +/-.1 of a grain doesn't matter much.

Quickload will not account for finding such flat spots, it will simply stay in a quasi linear line, increasing velocity incrementally with increases in velocity, where as real world tests will not match up quite the same. Remember, quickload is only a prediction..

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Dwh7271 · Jan 2, 2018

Code:

Cartridge          : 5.56 mm NATO - 5.56 x 45 mm
Bullet             : .224, 77, Nosler CC HPBT 22421
Useable Case Capaci: 23.989 grain H2O = 1.558 cm³
Cartridge O.A.L. L6: 2.260 inch = 57.40 mm
Barrel Length      : 20.0 inch = 508.0 mm
Powder             : Hodgdon VARGET

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.448% 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

-04.5  107    22.83   2669    1218   54711   8217     95.2    1.015  ! Near Maximum !
-04.0  107    22.94   2682    1230   55557   8254     95.4    1.008  ! Near Maximum !
-03.6  108    23.04   2695    1242   56422   8291     95.6    1.002  ! Near Maximum !
-03.1  108    23.15   2707    1253   57299   8327     95.8    0.995  ! Near Maximum !
-02.7  109    23.26   2720    1265   58190   8362     96.0    0.989  ! Near Maximum !
-02.2  109    23.36   2733    1277   59095   8397     96.1    0.982  ! Near Maximum !
-01.8  110    23.47   2745    1289   60015   8432     96.3    0.975  ! Near Maximum !
-01.3  110    23.58   2758    1300   60948   8465     96.5    0.969  ! Near Maximum !
-00.9  111    23.69   2770    1312   61896   8499     96.6    0.963  !DANGEROUS LOAD-DO NOT USE!
-00.4  111    23.79   2783    1324   62860   8531     96.8    0.956  !DANGEROUS LOAD-DO NOT USE!
+00.0  112    23.90   2796    1336   63839   8564     97.0    0.950  !DANGEROUS LOAD-DO NOT USE!
+00.4  112    24.01   2808    1349   64836   8595     97.1    0.944  !DANGEROUS LOAD-DO NOT USE!
+00.9  113    24.11   2821    1361   65851   8626     97.3    0.937  !DANGEROUS LOAD-DO NOT USE!
+01.3  113    24.22   2834    1373   66883   8656     97.4    0.931  !DANGEROUS LOAD-DO NOT USE!
+01.8  114    24.33   2846    1385   67933   8686     97.5    0.925  !DANGEROUS LOAD-DO NOT USE!
+02.2  114    24.44   2859    1398   69002   8715     97.7    0.919  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 5% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 5% relative to nominal value:
+Ba    112    23.90   2864    1402   69633   8586     98.8    0.916  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 5% relative to nominal value:
-Ba    112    23.90   2718    1263   58084   8446     94.2    0.988  ! Near Maximum !

Code:

Cartridge          : 5.56 mm NATO - 5.56 x 45 mm
Bullet             : .224, 77, Nosler CC HPBT 22421
Useable Case Capaci: 23.989 grain H2O = 1.558 cm³
Cartridge O.A.L. L6: 2.260 inch = 57.40 mm
Barrel Length      : 20.0 inch = 508.0 mm
Powder             : Hodgdon VARGET

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.446% 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

-04.5  107    22.93   2681    1229   55500   8252     95.4    1.009  ! Near Maximum !
-04.0  108    23.04   2694    1241   56364   8288     95.6    1.002  ! Near Maximum !
-03.6  108    23.14   2706    1253   57240   8324     95.8    0.995  ! Near Maximum !
-03.1  109    23.25   2719    1264   58131   8360     95.9    0.989  ! Near Maximum !
-02.7  109    23.36   2732    1276   59035   8395     96.1    0.982  ! Near Maximum !
-02.2  110    23.46   2744    1288   59953   8429     96.3    0.976  ! Near Maximum !
-01.8  110    23.57   2757    1300   60885   8463     96.5    0.969  ! Near Maximum !
-01.3  111    23.68   2770    1312   61833   8497     96.6    0.963  !DANGEROUS LOAD-DO NOT USE!
-00.9  111    23.79   2782    1324   62795   8529     96.8    0.957  !DANGEROUS LOAD-DO NOT USE!
-00.4  112    23.89   2795    1336   63774   8561     96.9    0.950  !DANGEROUS LOAD-DO NOT USE!
+00.0  112    24.00   2808    1348   64769   8593     97.1    0.944  !DANGEROUS LOAD-DO NOT USE!
+00.4  113    24.11   2820    1360   65782   8624     97.2    0.938  !DANGEROUS LOAD-DO NOT USE!
+00.9  113    24.21   2833    1372   66813   8654     97.4    0.932  !DANGEROUS LOAD-DO NOT USE!
+01.3  114    24.32   2845    1384   67862   8684     97.5    0.926  !DANGEROUS LOAD-DO NOT USE!
+01.8  114    24.43   2858    1397   68930   8713     97.7    0.920  !DANGEROUS LOAD-DO NOT USE!
+02.2  115    24.54   2871    1409   70017   8742     97.8    0.913  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 5% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 5% relative to nominal value:
+Ba    112    24.00   2875    1414   70648   8609     98.9    0.911  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 5% relative to nominal value:
-Ba    112    24.00   2730    1274   58931   8481     94.4    0.982  ! Near Maximum !

Code:

Cartridge          : 5.56 mm NATO - 5.56 x 45 mm
Bullet             : .224, 77, Nosler CC HPBT 22421
Useable Case Capaci: 23.989 grain H2O = 1.558 cm³
Cartridge O.A.L. L6: 2.260 inch = 57.40 mm
Barrel Length      : 20.0 inch = 508.0 mm
Powder             : Hodgdon VARGET

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.445% 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

-04.4  108    23.03   2693    1240   56306   8286     95.6    1.003  ! Near Maximum !
-04.0  108    23.14   2706    1252   57182   8322     95.8    0.996  ! Near Maximum !
-03.6  109    23.24   2718    1263   58071   8358     95.9    0.989  ! Near Maximum !
-03.1  109    23.35   2731    1275   58974   8393     96.1    0.983  ! Near Maximum !
-02.7  110    23.46   2744    1287   59891   8427     96.3    0.976  ! Near Maximum !
-02.2  110    23.56   2756    1299   60823   8461     96.4    0.970  ! Near Maximum !
-01.8  111    23.67   2769    1311   61769   8494     96.6    0.963  !DANGEROUS LOAD-DO NOT USE!
-01.3  111    23.78   2781    1323   62731   8527     96.8    0.957  !DANGEROUS LOAD-DO NOT USE!
-00.9  112    23.89   2794    1335   63708   8559     96.9    0.951  !DANGEROUS LOAD-DO NOT USE!
-00.4  112    23.99   2807    1347   64702   8591     97.1    0.944  !DANGEROUS LOAD-DO NOT USE!
+00.0  113    24.10   2819    1359   65714   8622     97.2    0.938  !DANGEROUS LOAD-DO NOT USE!
+00.4  113    24.21   2832    1371   66744   8652     97.4    0.932  !DANGEROUS LOAD-DO NOT USE!
+00.9  114    24.31   2845    1384   67792   8682     97.5    0.926  !DANGEROUS LOAD-DO NOT USE!
+01.3  114    24.42   2857    1396   68858   8711     97.7    0.920  !DANGEROUS LOAD-DO NOT USE!
+01.8  115    24.53   2870    1408   69944   8740     97.8    0.914  !DANGEROUS LOAD-DO NOT USE!
+02.2  115    24.64   2883    1421   71049   8768     97.9    0.908  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 5% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 5% relative to nominal value:
+Ba    113    24.10   2887    1425   71678   8631     99.0    0.905  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 5% relative to nominal value:
-Ba    113    24.10   2742    1285   59793   8516     94.6    0.976  ! Near Maximum !

Dwh7271 · Jan 2, 2018

The ones you want are at the +00.0 on each run

Polaris · Jan 2, 2018

So, looks like 23fps predicted. Now I will crunch some more numbers and see what happens.

Polaris · Jan 2, 2018

Interesting, .2 grain variation in this scenario works out to aprox. .2" at 300 yards using Nosler published G1 and Hornady's ballistic calculator, zero set at 200. Perhaps enough to split a line or not, but not a very significant difference. Velocity spread is probably within that obtainable with the fictional perfect charge weight. My internet is slow right now, so didn't attempt to plug in wind, but assume the results would be similarly unspectacular.

Seems to put the weighed vs thrown charge debate to bed, at least to 300 yards. At 600, the spread increased to 1.4", definitely significant. Still small compared to environmentals at that distance, but variables seem to multiply more than they randomly cancel, so I'll be sticking to weighed for long line.

Would be interesting to see Hornady, Nosler, or one of the other interested concerns do a more controlled study on this with real rounds downrange in as controlled an environment as possible.