12.7mm does it deserve the range?

[chuckfourth]

Hi All
I have been interested in the anomalous range given to the 12.7mm calibre. AFAIK all weapons in the game of this calibre have a range of 2000 meters, whereas machine guns in the 7.62 have ranges of 1500 metres. When we move up to 20mm calibres these weapons ranges drop back down to 1500 m. At 37mm calibre the range has only just managed to return to 2000m. So I ask myself why does the 12.7mm calibre have such an extraordinary range?
Well a lot of people will tell you that the 12.7mm calibre has the perfect Ballistic Coefficient (BC) giving it great stability out to 2000m and further, however even the 7.62mm round remains stable at this range so actually the BC is irrelevant when considering ranges under 2000m.
But if you are interested in these things then then we can compare the 7.62mm, 50 cal and the 20mm Hispano cannon rounds using information from
http://www.quarry.nildram.co.uk/ballistics.htm
to calculate BC we use BC = sectional density(SD) * Form Factor(FF)
we can use the supplied FF
"Pointed full jacket: FF = 1.5-1.8"
lets use an average value of 1.65

we get,

7.92______SD of .27____* by 1.65 gives .45
50 cal____SD of .37___ * by 1.65 gives .61
20mm______SD of .47____* by 1.65 gives .78
Im no expert on ballistics and FF's vary but it looks like the bigger the calibre the better the range. which is why I an curious as to why the 12.7s out-range the 20mm cannon and equal the 37mm cannon, especially as the 12.7's are firing over open sights whereas the 20mm and 37mm cannon usually have an optical sight.

You can easily find references quoting 2000m as the range for the 50 cal (12.7mm). However if one looks a little closer one finds that the 50 cal has two ranges 2000m for "area targets" and 1500m for point targets. see

http://www.geocities.com/Pentagon/Qu...83/page30.html amongst many others. Actually this site gives 1830m rather than 2000m for "area shot"
As the game does not model area fire I dont see that the 2000m "area fire" range is appropriate.
For the calibre in russian hands there is this for BTR-60 from

http://warfare.ru/?linkid=2296&catid=245

"Maximum Aimed Range (m) 1,500"

This is interesting as 1500 is the maximum "aimed range" ie this is as far as the simple "open" sights can be used. Note that the 7.62mm Machine guns also have 1500 as maximum range. As the 7.62mm rounds travel further than 1500m It looks as though 1500m has been chosen as this is the maximum range at which the sights can be used. If this is the case then as the sights on 12.7mm calibre weapons and 7.62mm weapons are the same they should both have the same range, 1500m.
Bottom line, I think the sights on the 12.7mm weapons limit their effective range to 1500m

The 15mm Besa and Italian 13.2mm calibres also have the 2000m range.
Best Regards Chuck.