Calculated "base" dispersion of guns based on energy delivered

[HoHun]

Hi Rshubert,

>The browning short recoil system has been used for highly accurate premium grade hunting rifles, many of which are capable of 1 MOA or less accuracy.

I don't really see a contradiction here as the single-shot accuracy of a weapon is way better than rapid fire accuracy of the same weapon.

The effects you're describing seem to confirm our idea that mounting weapons in aircraft is not good for their accuracy ;-)

>As has been said, there are MANY factors.

No doubt about that :-)

Regards,

Henning (HoHun)

[Tony Williams]

Originally posted by rshubert
For once, I disagree with you Tony.  Carlos Hathcock, a famous Vietnam era Marine Sniper, once made a one-shot 2500 yard (measured) kill with a scope mounted M2 HB machine gun using standard military issue ball ammo.  It's documented in the book, Marine Sniper.  I don't have the ISBN or author handy--I'm at work right now.  The browning short recoil system has been used for highly accurate premium grade hunting rifles, many of which are capable of 1 MOA or less accuracy.

First, I entirely agree that accuracy is a complex issue and is affected by many elements. The key point is consistency: the ammunition has to perform in exactly the same way from shot to shot, so does the gun, so does the mounting. Precision in manufacture of the gun and ammunition is a vital element.

I doi not doubt that the Browning short-recoil action can be made to perform well, if made very carefully with precision in mind. But precision means extremely tight tolerances, which is just what you don't need in a military weapon, since that reduces reliability and very likely also (in a machine gun) rate of fire. The well-known facts that the Kalashnikov is more reliable than the M16, but less accurate, are not unconnected.

I believe that Hathcock's gun was modified in more ways than just having a scope added, although I've never been able to discover the details. But I do know that Hathcock himself admitted that a fair amount of luck was involved with that kill. Even if the gun was perfectly accurate and precisely aimed, the accuracy standard of the military grade .50 ammo was such that most shots would have missed such a small target at such a long range. The accuracy standard of the ammo fired in modern .50 cal rifles is much higher.

Tony Williams: Military gun and ammunition website and Discussion forum

[GRUNHERZ]

Guys please stop trying to argue that the accuracy of single,  expertly aimed, carefully crafted, high power scope assisted 50 caliber shots from highly modified long/heavy barell weapons fired from stable positions and conditions on the ground has any bearing or relevancy on the accuracy of rapid fire, short/light barrel, 50 cals aimed by unmagnified sights and fired from the rather flexible wings of vibrating, turning, accelkeratin flying airplanes in a very high drag high airspeed enviorment...

OK?

Please....

[JB73]

i have NO knowledge whatsoever on this topic but a few thing have stood out.. first this:

Originally posted by Wotan
Take the tail turret on the b17, 45ft dispersion at 600yrds. You can't really believe that would help determine the dispersion of the p51.

there is NO way we have this "model" in AH. not even close. if that is RL then we have "lazer guns" as many times said on bombers.

i KNOW this has been brought up as a gameplay discussion, the bombers fire more accuratly than RL because of thies vulnerabliity in the game withough giant formations like RL. problem is now a formation now fires on you with the accuracy of the "gameplay" consideration.


also

Originally posted by HoHun

The formula matches the following historical dispersion values:

MG FF/M - 1.0 mil
MG 151/20 - 1.9 mil
MK 108 - 1.5 mil
MK 103 - 2.0 mil

It extrapolates the following dispersions:

Browning 12.7 mm - 2.1 mil
Browning 7.7 mm - 3.3 mil
Hispano II - 2.5 mil

if these calculations are correct, then whay are the hispanos with the highest "dispersion" more a stable and accurate platform in AH than the 30mm which this data shows to be much more "accurate"

if i am reading this data correctly.

thank you for your time

[Tony Williams]

I think that Henning maybe needs to look at that formula. We've seen info from RL earlier in the thread which shows that the Hisso was more accurate than the .5 Browning (4 mils v 5 mils, IIRC)

TW

[Wotan]

Originally posted by JB73
i have NO knowledge whatsoever on this topic but a few thing have stood out.. first this:

 there is NO way we have this "model" in AH. not even close. if that is RL then we have "lazer guns" as many times said on bombers.

i KNOW this has been brought up as a gameplay discussion, the bombers fire more accuratly than RL because of thies vulnerabliity in the game withough giant formations like RL. problem is now a formation now fires on you with the accuracy of the "gameplay" consideration.


also
 if these calculations are correct, then whay are the hispanos with the highest "dispersion" more a stable and accurate platform in AH than the 30mm which this data shows to be much more "accurate"

if i am reading this data correctly.

thank you for your time

Pyro has or has the book where that data comes from.  These were ground tests btw. I would imagine (could be wrong) that dispersion was worse in flight (air stream, aircraft vibration etc...)

[HoHun]

Hi Tony,

>I think that Henning maybe needs to look at that formula.

JB was quoting the old results which I provided without the additional data points for Hispano II and Browning M2 :-)

The new formula gives more accurate results.

Regards,

Henning (HoHun)

[HoHun]

Hi again,

While I'm at it:

Firepower per barrel in MW:
MK 108:          5,03 MW
MK 103:          4,08 MW
NS-37:           2,17 MW
MG 151/20:       1,27 MW
Hispano V:       1,23 MW
VYa-23:          1,20 MW
Hispano II:      1,06 MW
37mm M4:         0,91 MW
20mm Ho-5:       0,71 MW
20mm Type 99-2:  0,63 MW
20mm Type 99-1:  0,52 MW
MG-FF:           0,78 MW
Berezin B-20:    0,64 MW
Ho-1 / Ho-2:     0,64 MW
20mm ShVAK:      0,64 MW
MG 151:          0,44 MW
12,7mm UB:       0,37 MW
,50 Browning M2: 0,28 MW
MG 131:          0,21 MW
Ho-103:          0,18 MW
12,7mm Scotti:   0,14 MW
Breda-SAFAT:     0,14 MW
Browning ,303:   0,09 MW
MG 17:           0,09 MW

Regards,

Henning (HoHun)

[GRUNHERZ]

And that chart is meaningless since the hispano is obviously the far suerior weapon to MG151/20 in AH.  Not to mention that VYa-23 is vasty better than both. Also the AH Shvak is equal to MG151/20..  

[HoHun]

Hi Grünherz,

>And that chart is meaningless since the hispano is obviously the far suerior weapon to MG151/20 in AH.  Not to mention that VYa-23 is vasty better than both.

Well, the AH team pointed out they're open for suggestions :-)

Here's another interesting chart, showing energy density for fighter batteries based on the dispersion values I posted:

MK 108          ( 1 barrel,  5029 kW): 300 m - 5929/494 kW/m^2; 600 m - 1482/124 kW/m^2; 900 m - 659/55 kW/m^2
MK 103          ( 1 barrel,  4080 kW): 300 m - 2706/225 kW/m^2; 600 m -  676/ 56 kW/m^2; 900 m - 301/25 kW/m^2
MG 151/20       ( 2 barrels, 2536 kW): 300 m - 1864/155 kW/m^2; 600 m -  466/ 39 kW/m^2; 900 m - 207/17 kW/m^2
Hispano II      ( 2 barrels, 2123 kW): 300 m -  901/ 75 kW/m^2; 600 m -  225/ 19 kW/m^2; 900 m - 100/ 8 kW/m^2
MG-FF           ( 3 barrels, 2339 kW): 300 m - 6204/517 kW/m^2; 600 m - 1551/129 kW/m^2; 900 m - 689/57 kW/m^2
,50 Browning M2 ( 8 barrels, 2271 kW): 300 m -  376/ 31 kW/m^2; 600 m -   94/  8 kW/m^2; 900 m -  42/ 3 kW/m^2
Browning ,303   (25 barrels, 2188 kW): 300 m -  232/ 19 kW/m^2; 600 m -   58/  5 kW/m^2; 900 m -  26/ 2 kW/m^2

As a guide to this chart: These values are absolut power density so that they can be easily compared. For example, it's evident that at each range, the MK108 is more lethal at the rim of its pattern than the 12.7 mm Browning M2 eight-gun battery is in the centre of its pattern.

Regards,

Henning (HoHun)

[HoHun]

Hi again,

Here the results of my calculations.

I didn't have a barrel length for the MG17 or the Berezin B-20, so they're not included in the list.

In general, I've got to say that there were few surprises in the list.

It's worth noting that the MG FF/M and the Browning .303 did indeed define the opposite ends of the scale and all additional guns came in between 1,5 and 3,4 mil dispersion.

MG-FF:             1,0
MK 108:            1,5
20mm Type 99-1:    1,5
20mm Type 99-2:    1,5
Ho-1 / Ho-2:       1,5
12,7mm Scotti:     1,6
Breda-SAFAT:       1,7
MG 131:            1,7
20mm Ho-5:         1,9
MG 151/20:         1,9
MK 103:            2,0
20mm ShVAK:        2,0
Hispano V:         2,1
37mm M4:           2,1
Ho-103:            2,2
VYa-23:            2,5
12,7mm UB:         2,7
Hispano II:        3,0
NS-37:             3,3
MG 151:            3,4
,50 Browning M2:   4,0
Browning ,303:     4,2

Regards,

Henning (HoHun)

[Tony Williams]

Why the difference between the MG-FF and the Type 99-1? They were very similar versions of the Oerlikon FF.

Tony Williams

[HoHun]

Hi Tony,

>Why the difference between the MG-FF and the Type 99-1? They were very similar versions of the Oerlikon FF.

Oops. I mistook the total length of the gun for the barrel length :-)

So it is:

20mm Type 99-1:    1,0

Regards,

Henning (HoHun)

[HoHun]

Hi again,

I just found an interesting comment on the effectiveness of 0.303" guns:

"Three Fulmars of 809 Squadron expended 18,000 rounds on a BV 138 without inflicting any obvious damage." =8-O

(David Brown, Profile Aircraft 254, "Fairey Fulmar Mks I & II")

Regards,

Henning (HoHun)

[Crumpp]

Here is some food for thought.

Enjoy.







Crumpp