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Field
Results
 Case
#1: Finding that Optimum Load
The challenge was to find
the optimum load for a .30-30 Winchester rifle using the 150 gr. Sierra
Spitzer bullet.
We first needed to measure
the barrel length and the case capacity of the cartridge. The full case
capacity was determined by subtracting the weight of an empty case from
the weight of a case filled with water. Using "Load From A Disk"
we could determine the effective case capacity (case volume with seated
bullet) by providing the bullet data and the full case capacity. The
software also determined the effective barrel length (actual distance
traveled by the bullet). The effective case capacity was 38.1 gr. of
water and the effective barrel length was 20.49 inches.
Next, "Load From A
Disk" developed the cartridge load. What's great was it required
only one click of the mouse to get the load data. It remembered the
original data inputs and used the information it had already calculated
to come up with the final results. Below is a summary of outputs.
| Summary
of Outputs |
| Powder
Class: |
Medium
Fast Powders (Class 11) |
| Powder
Type: |
IMR
3031, RL-12, H335, AA2230, WW748, N-201, AR2206 |
| Charge/Bullet
Weight: |
0.22 |
| Calculated
Powder Charge: |
32.8
gr. |
| Load
Density: |
86% |
| Estimated
Chamber Pressure: |
42,390
psi |
| Estimated
Muzzle Velocity: |
2,310
ft/sec |
Then we loaded several
rounds using 32.8 grains of selected powders suggested by Load From
A Disk. We then chronographed the actual muzzle velocities using a Remington
model 788 rifle. Below are the field results for each of the selected
powders.
| Field
Results |
| IMR
3031: |
2,332
ft/sec |
| Hercules
RL-12: |
2,372
ft/sec |
| Hodgdon
H335: |
2,359
ft/sec |
| Winchester
748: |
2,107
ft/sec |
Note the velocities from
each powder (except Winchester 748) were within 3 percent of Load From
A Disk's predicted velocity of 2310 ft/sec. The Winchester 748 powder
was 9 percent lower.
ICase
#2: Wildcat Cartridge
Several years ago I developed
a cartridge dubbed the 6.35X47. Essentially, it was a .222 Remington
Magnum case necked-out to hold a 0.25 caliber bullet. Since data was
not available for this cartridge I had to develop the load based on
the 0.222 Remington Magnum parent cartridge. Let's see what Load
From A Disk would do with it.
A 75 gr. Sierra bullet
was seated in several reformed cases and these cases filled with water
to determine its capacity. These cases were found to hold an average
of 29.4 gr. of water. The cartridge was chambered in a rebarreled Remington
700 BDL rifle and the effective barrel length was found to be 20.51
inches. This information was entered into Load From A Disk. The
following output was obtained.
| Summary
of Outputs |
| Powder
Class: |
Medium
Fast Powders (Class 11) |
| Powder
Type: |
IMR
3031, RL-12, H335, AA2230, WW748, N-201, AR2206 |
| Charge/Bullet
Weight: |
0.34 |
| Calculated
Powder Charge: |
25.3
gr. |
| Load
Density: |
86% |
| Estimated
Chamber Pressure: |
42,324
psi |
| Estimated
Muzzle Velocity: |
2,774
ft/sec |
The actual chronographed
velocity for the calculated powder charge was 2,823 ft/sec, only 1.7
percent higher than the calculated velocity. For those interested
in further details on this cartridge they can be found in the February
1977 edition of Shooting Times.
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