Hey guys, thanks for tuning in to another video on Forgotten Weapons dot com
I'm Ian McCollum
and today's video is a correction
so a couple of weeks ago I did a video on a Confederate Whitworth rifle
and one of the things I point out in that video
was the extreme accuracy of the Whitworth at the time
now the Whitworth was an extremely accurate rifle for its time
however, it wasn't quite as accurate as I said it was
so, I had a number of people, three in particular
point this out to me after that video published
those people being, uh
John Simpson, who is the author of a couple of books on sniping
David Minshall, who runs a website called Research Press
in the UK on long-range shooting
and Rob from the YouTube channel BritishMuzzelLoaders
now, these guys all were telling me the same thing and that is
what I read off as, what I identified as minute of angle groups
as in the size of an entire group
on paper for the Whitworth rifle
were in fact not measurements of group size
but measurements of something called "Figure of Merit"
and Figure of Merit was how the British military measured its rifle accuracy
at this time period
and this trial that I was referencing here took place in 1857
now to make things a little bit more complicated
there's an American term Figure of Merit
and there's also a British term for Figure of Merit. Now in American parlance
Figure of Merit means taking the extreme
horizontal spread and the extreme vertical spread of the group
and averaging them. But,
we're not even going to bother talking about that
because that has nothing to do with our story about the Whitworth
The British version of the Figure of Merit is what we would call
"Mean Radius" or "Mean Radial Dispersion"
and what that means is that you would fire a group, and in this case the British standardized
on a twenty shot group. You then mathmatically
find the center point of the group. Then...
you measure the distance from that center point to each individual
bullet hole. You add all of those up
and you average them. And the average of
distance from the center of the group to the bullet hits
is your Figure of Merit in British terminology.
Now what this does is actually give you a very valuable measure of
how well a rifle shoots.
Because it's going to assess the overall size of the group.
or rather, the consistency of the group.
If you have an extremely tight group with one weird flier
measuring it in this way minimizes the impact of that flier
in a way that
simply measuring group size simply doesn't.
So for example, if we had twenty shots,
and let's say nineteen of them are in a one inch circle
right smack in the middle
And you've got one flier out here a foot away
That's called a twelve inch group. If you have
ten fliers, all about twelve inches away
you still have a twelve inch group.
However, we know that a group with nineteen shots in the circle
and one flier is better than one with
this random dispersion of twenty shots
through a twelve inch group. And the British Figure of Merit terminology
does a much better job of assessing
that sort of comparative quality.
So at any rate, this is how the British were measuring accuracy.
And in this rifle trial, for example,
at 500 yards - and by the way, this is yards
because the British at this time were using yards
the Whitworth rifle had a Figure of Merit
of .37 feet which is about four and a half inches.
So what that tells us
is that the average distance from the center point of the group
not the aiming point, the center point of where all the shots hit
The average distance from the center to each shot
was about four and a half inches.
Now, I wanted to figure out how to convert this in to something like
Minute of Angle, total group size
to give you guys, and myself for that matter
a way of understanding this group that makes sense
to what we're used to, so
Mr Simpson, John Simpson, was thoughtfully able to
provide me with the mathematical numbers to do that
in order to go from Figure of Merit to group size
you basically are doing statistical
... sort of statistical analysis.
You can never tell the actual size of the original group
from a Figure of Merit number, but you can tell statistically
what it probably was, and so
with a twenty shot group we're going to multiply our Figure of Merit
by... 3.643
and that will give us statistically the overall
size of the group. We're then of course going to divide
by 5.235 which will convert
a group size in inches at 500 yards
to a Minute of Angle measurement
and using this, what we actually see for the Whitworth's accuracy
at 500 yards is 3.1 Minute of Angle
that is still a really remarkably impressively
accurate rifle for 1857.
It shouldn't be downplayed.
Obviously I should have done my own due diligence better.
I should have realized a sub Minute of Angle muzzle loader
really doesn't pass the "smell test".
But I didn't and that's on me, certainly.
So what we actually have with the Whitworth
at 500 is 3.1 Minute of Angle
for sake of comparison if we do the same conversion
to the Enfield musket
which was the British military long arm of the time
and it's what the Whitworth was being compared against
The Enfield had a Figure of Merit of 2.24 feet
at 500 yards, which comes out to
18.7 Minute of Angle, so
the group fired by the Whitworth was something like
one sixth the size of the group fired by the Enfield.
This should put in to perspective just how much more accurate the Whitworth was
than its competitors.
And, unfortunately, I think people may downplay how impressive that number is
because I said, originally
in the first video that it was, in fact
something much better than that.
If we go all the way out, the longest range
that they actually continued to fire the Enfield at
was eleven hundred yards. Beyond that
the Enfield wasn't making hits on target and they could do a twenty shot group
At eleven hundred, the Whitworth was still making
twenty Minute of Angle to the Enfield's
sixty one Minute of Angle. Now keep in mind that
at eleven hundred yards we are well past the distance at which both of these
rifles went from supersonic
... both the projectiles from both the rifles went from supersonic to subsonic
and when that happens accuracy tends to degrade
as the bullet passes through it's own sonic boom
and tends to destabilize.
So twenty Minute of Angle doesn't sound very good
but I tell you what - at eleven hundred yards
that is certainly no mean feat, especially for a muzzle loader
in 1857.
Anyway, this has just been a short video
to issue a formal correction. I think it's the first time
I've had to do that
And I will be more careful in the future
and try to avoid ever having to do one of these again.
But hopefully, aside from just making a correction
you learned something new today
about how accuracy has been measured in different times and places.
Thanks very much for watching and we'll be back tomorrow with another
interesting Forgotten Weapon.