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Discussion Starter · #1 · (Edited)
I am Trying to Interpret data from a series of USMC 1940 Firing Trials. This is test data for trials for a variety of rifles to include: M1 Garand, Sprinfield 03 Bolt Action, Johnson Semi-Automatic Rifle, and the Winchester .30 Caliber Semi-automatic.
See the following URL for the info I am talking about.

http://yfrog.com/jk54165984jx

I was hoping for some help in interpreting some of the tabulated data resulting from these tests. I know what a figure of merit is and I know how it is determined, but that’s about the extent of what is recognizable to me.

My questions are:

1) What do the various targets look like? Are the A, B, C, and D targets they refer to some sort of standard Marine Corps targets – see Table-II? If yes does someone know what they look like – how big – are they bullseye targets; or are these man shaped slihouette targets or what?
2) How are the shooting scores determined in Table-III. Is it safe to assume that a higher score means better shooting or what? How are points being awarded?
3) Do the MV and MH numbers shown in Table IV refer to “Mean Vertical Radius” and “Mean Horizontal Radius”?

See the following URL for the info I am talking about.
http://yfrog.com/jk54165984jx

Thanks a bunch for any help.
 

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Based on the scores, the targets are the old National Match standard V-ring targets. These were targets with a series of concentric rings with the largest being the lowest score and the next-to smallest being a maximum score of 5 points possible for a shot, so 50 was a perfect score for a string of 10. A final smaller ring was inside the 5 ring at the center to serve as the tie-breaker, and was labeled with the Roman numeral V (to distinguish it from the larger ring that scored Arabic numeral 5). The V-ring is where the series of targets got its name.

As rifles and shooters got better over time, too many “possibles” (all V-ring hits) were being fired on these targets, resulting in lots of ties despite the small V-ring, and shoot-off targets had to be fired after regular match time to break ties. Some of those went on for some time. As a result, the targets were finally revised to the current targets that have smaller inner rings and score a maximum of 10 points per shot, and which have a smaller center tie-breaking ring inside the 10-ring that is labeled with the Roman numeral X. These are collectively called X-ring targets.

Like the current X-ring targets, the old V-ring series consisted of separate targets for slow fire (smaller rings) and rapid fire (bigger rings) and scaled versions use at different target ranges. The scaling is done in particular because most ranges don't have 600 yard firing points, many don't have 300 yard firing points, and others don't have 200 yard firing points available. So targets are scaled as small as 100 yards. It looks like they used slow fire targets scaled to 200,300, and 600 yards in the tests.

The tests were looking two separate things: Shooter score achieved on those targets, and group size. The latter is a separate matter for two reasons. One is that the ammo doesn’t know where the sights are set, so group size better reflects mechanical accuracy of the gun and ammunition without regard for the sights or where the shooter’s eye sees the bullseye located, which shifts up and down over iron sights as the brightness of ambient light conditions change during the shooting day.

The second, and more important reason is that a score might be the same if the ammo consistently grouped about the ten ring size for one batch of ammo, and grouped tighter 9 times out of 10 for another, with every tenth shot being a flier two rings out. The first ammo would be better for match shooting as the latter would randomly produce some boxes of ammo that were all tight center shooters and others that were all flier rounds, and that would make a competition unfair.

MV and MH are the mean deviation (average deviation for all the test groups fired at each target type and range). These days the initials are MHD and VHD. From Geoffry Kolbe's, A Ballistic Handbook:

"The Mean Horizontal Deviation or MHD is defined as the average of the absolute or unsigned deviations from the sample mean of the x components. This is also known as the Mean Absolute Deviation and the Mean Deviation From The Mean. . .
The typeface doesn't make the formula easy to type here in the quotation, but it isn't at all hard to work out. You pick some point to be 0,0, the origin point on the target, giving it the coordinates, H,V. I just use the lower left corner of the target so the left edge of the paper is zero for the horizontal measurements and the bottom edge is zero for the vertical measurements. Locate each hole's horizontal and vertical distance from that origin point and record them. Average the horizontal values and average vertical values. These two averages constitute the horizontal and vertical position of the center of the group.

For the MHD, you need to find every hole's horizontal distance from the horizontal average result you got above, then average them. This is just a distance magnitude and has no sign, so it is simply the difference between the average horizontal group center value found earlier and the horizontal value for each individual hole, removing any - sign that turns up when you do the subtraction so you have all positive numbers. Add them up and divide them by the number of holes in the group. That's the MHD. Repeat with the vertical values to find MVD.

You should be able to take the target numbers given on those tables and find the scoring ring diameters for the three full-range V-ring targets somewhere? The current X-ring target scoring ring sizes are in the rule book for highpower rifle matches, and are available for free PDF viewing at the NRA site. See section 4 here to get an example of the format. What you need is one that precedes the target change. I don't happen to know them offhand. Can't recall if Hatcher's Notebook listed them? You might call the National Target Company and ask if they still know?
 

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Discussion Starter · #3 ·
Excellent reply. Thanks very much Nick.

I looked through Hatcher's Notebook, but nothing jumped right out at me regarding what the A,B,C and D targets looked like, or how scoring was determined. Probably an old Marine Corps Field Manual might do the trick.

Can I PM you with an additional question regarding interpretation of the test data?

Thanks again
Marty
 

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Discussion Starter · #4 ·
Sorry -- I forgot to cite the original source of the USMC test data I posted above.

J. Hatcher's "Hatcher's Book of the Garand, Development of Semiautomatic Rifles", The Gun Room Press, 1948. See pages 141 - 150.
 

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Sionaprhys,

Thanks for posting that PDF. It's now in my data file.


Marty,

You might see if you can get a copy of the Kolbe book on inter-library loan? It's really meant to be a small handbook for people familiar with the math of ballistics, having lots of shortcut equations, but also a few spots where you need to be familiar with the terminology and standard symbol usage. There is, however, a chapter (seven) with just five short pages of stats for evaluation of ammo, describing the industry standard methods. ISBN 0-9537537-0-0.

Feel free to PM, but post anything you think the response to may be of interest others?


P.S., Hatcher's Book of the Garand is one of my favorites. Chock full of information. Anyone who owns a Garand should have a copy.
 
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