I personally think the current open fire range is reasonable considering its a game average, has historical precedence and IMO is somewhat in the realistic ball park. Why not just arbitrarily make the open fire range 300 yards? 500 yards? 1000 yards?...based on what 'some' CW units might have done during the war?
As i said earlier, in the hands of a competent marksman with the right rifle, the right ammo, the right weather conditions and with no life-threatening stresses, a good Enfield or Springfield is certainly capable of reasonable accuracies at 200 and slightly above yards from the bench. Offhand is another thing.
After firing hundreds of minie balls out of my 3-band Enfield on a good day shooting offhand i can get a two inch or so center to center group. I once tried the local 200 yard range one day also offhand, and after a couple hours, 50 or so balls, and a 1/2 pound of powder later, the best i could do was a 12 inch center to center group with a couple flyers and that was after a whole bunch of trial 'n error sight adjustments to even get on the 3 foot by 3 foot target. With more practice...who knows?
Why the big difference from 100 yard to 200 yard accuracy discrepency?
I didn't want to get into ballistic physics but plain and simple the CW minie ball propelled by BP in a CW era rifled musket while it is superior to a smooth bore musket is not the best choice for extreme long range accuracy. In a loose sense analogy these muskets can be thought of obeying the inverse square law, that is the further the ball travels the accuracy drops much greater than as a linear function.
Why is this?
-The CW minie ball although there were variances typically has a large diameter to length ratio...its stubby compared to modern bullets! Right off the bat this means the rifling twist (revolutions/foot) cannot be too aggressive or it would strip the lead right off the ball causing accuracies worse than a smooth bore. Because of this the rifling effect of spinning the bullet like a spirralled football to gain stability is not the best. The official Enfields imported from England used progressive rifling to somewhat compenstate for this.
The famous sniper rifle of the CW was the Whitworth capable of long range accuracy primarily because of its lower dia. to length ratio which made it more stable in flight. If i remember correctly it used a long solid .45 caliber bullet and also hexagonal rifling to help combat poor accuracy due to BP fouling.
-The minie ball has a relatively poor ballistic coefficient compared to modern bullets. This basically means it presents more drag due to air resistance which helps the poor trajectory path. Even if it were possible, minie's would be extremely unstable at supersonic velocities especially considering the relatively slow rifling twist rate it requires.
-Because of its heavy weight, relatively poor ballistic coefficient and slow velocity of under 1000 fps, the CW minie propelled with only the typical charge of 60 grains of 2F BP has an extreme trajectory arc as compared to modern high-power rifles. Think of McDonalds Golden arches. This makes adjusting the elevation setting on the rear sight absolutely critical for any kind of reasonable accuracy at extreme long ranges. I just don't see a CW grunt starting to shoot at an assaulting enemy at 250 yards and finaggling with the rear sight adjustment as the enemy line draws closer. Maybe many did but i'll bet most didn't.
-For all the reasons mentioned above, accuracy is also negatively affected by cross winds. There are no easily adjustable windage settings on the rear sights of those old muskets. 'Kentucky windage' has to be used in the heat of battle. They just were not intended for long range sniper type accuracy. I don't have the ballistic tables in front of my right now but a heavy cross wind can throw one of those minie's off the sight picture by a few feet at those long distances.
-gyroscopic precession also has to be compenstated for at longer ranges. Basically what this means is that the rotating bullet will drift to the right or left depending on how the rifling twist direction was machined. From my experiences shooting my Sharps 45-70's, this effect is just about negligable under 100 yards but it definitely has to be compenstated for beyond a 100 yards by rear sight windage adustments.
-at some point the rotational inertial energy component of the bullet's total energy approaches zero causing it to become unstable and possibly even tumble end over end causing whats known as a 'keyhole' in a paper target. Been there, done and seen that unfortunately. Modern high powered rifles with fast aggressive twist rates, high ballistic coefficient copper jacketed bullets, supersonic velocities and no BP fouling are for the most part immune to this effect.
In the end, Norb is gonna do what Norb is gonna do. I suppose if there's enough pressure it'll be increased. Maybe a compromise would be to increase the distance a little under certain battle conditions.
As for me personally, i'd be content if its left alone.
