Armored 
Medical Research Laboratory 
Fopit Knox, Kentucky 
Second Partial Report 
On 
PROJECT NO. 21 - DETERMINATION OF THE SOURCES, MAGNITUDE 
AND COSTS OF GUNNERY ERRORS 
Project No* 21 
16 June 1944 ARMORED MEDICAL RESEARCH LABORATORY 
Port Knox, Kentucky 
Project NOo 21 
472c1 SPMEA 
16 June 1944 
Second Partial Report On 
1® PROJECT; Noe 21 - Determination of the Sources, Magnitude and 
Costs of Gunnery Errors„ 
a° Authority: Letter, Office of The Surgeon General, 24 March 
1944o 
b0 Purpose: To obtain further quantitative data to serve as a 
basis for critical evaluation of the capacities, limitations and expecta- 
tions in firing on the move with the gyrostabilizer0 
2« DISCUSSION: 
a0 The need for quantitative data on the effectiveness of fire 
with the ?5 mm gun that can be maintained with present gun stabilization 
equipment from the moving tank was pointed out in the First Partial Report0 
b0 The present report deals with the effectiveness of moving 
fire, using the coaxial machine gune The basic test procedures were the 
same as employed in the previous tests and, were selected for favorable 
operation of the gyrostabilizer. Only the nature of targets and tank 
speeds were varied to approximate more nearly the combat conditions for 
use of the machine gun« Comparative tests were conducted with and without 
the gyrostabilizer, at tank speeds of 2 and 10 raph and against three types 
of targets: large, exposed panels; so-called area targets of considerable 
length and limited height; and standard silhouette of head-on prone raanQ 
Co The test procedures and results are presented in the 
Appendix0 
3o CONCLUSIONS: 
a0 The effectiveness of moving fire with the coaxial machine 
gun was found to be relatively low compared with stationary fire, 
owing to the limited stabilization provided by the present equiprnento 
b« The effectiveness of moving fire with the gyrostabilizer 
was found to decrease sharply at ranges greater than 250 yds0 c0 The number of rounds required to obtain one hit on a 
silhouette target of a head-on, pron$ man, witji and without the gyro- 
stabilizef in operation, over smooth ground at two tank speeds and at 
ranges, up to 500 yards, were as follows; 
Mean 
Range 
Yds o 
With Gyro 
Without Gyro 
2 mph 
10 mph 
2 mph 
10 rnph 
100 
5.0 
l6o0 
3.6 . 
33.0 
250 
5o3 
13.0 
803 
18o0 
500 
28„5 
100.0 
19o0 
53.0 
do At a tank speed of 2 mph over smooth ground against a head-on 
prone man target no advantage was seen in moving fire with the gyrostabili- 
aer over fire from the non-stabilized gun and only limited improvement was 
observed at 10 mphQ 
e0 At a tank speed of 2 mph over smooth ground, against area 
targets, use of the stabilizer gave no improvement over the non-stabilized 
gun0 At 10 mph, the concentration of fire from the moving tank without use 
of the gyrostabilizer was reduced approximately one thirdo 
40 RECOMMENDATIONS: 
ac That the data contained in this report be considered in de- 
cisions with respect to future use of the present stabilization equipment and 
in the development of tactical plans which involve firing on the move0 
b0 That in any further development of gun-stabilizing equipment 
for moving fire, provisions be made for horizontal as well as vertical 
stabilization and that the necessary degree of stabilization be determined 
in relation to size of targets to be engaged and maximum range of fire to 
be employed so that the reaction time of the gunner will have minimum 
influence upon the precision or frequency of fire from the moving tank0 
Co That tests of any future gun-stabilizing equipment (apart from 
tests for determining mechanical reliability or problems of maintenance) be 
based upon quantitative measurements of precision of fire and rate of 
effective fire over the same courses against targets at various ranges out 
to the range of maximum employment, and that these be evaluated in relation 
to measurements of angular travel of the gun relative to the targets0 
Submitted by: 
ToF.Hatch, Lt. Col., SnC 
Glasselle S0 Lawson, 1st Lt., Info 
JoG.Daily, , FA (Armd, School) 
APPROVED 
WILLARD MACHLE 
Colonel, Medical Corps 
Commanding 
2 InclSo 
#1 - Appendix w/tables 1 thru 6 
#2 - Figures 1 thru 17 APPENDIX 
I. RELATION TO PREVIOUS REPORT; 
A previous report* dealt with the capacities and limitations of the 
gyrostabilizer employed in moving fire with the 75 mm gun in the M4 medium 
tank. The present study, whifeh is a continuation of the previous work, 
considers its operation with the coaxial machine gun. The objectives remain 
the same: to secure quantitative data on the degree of precision than can be 
expected in moving fire, in order to define and properly limit the conditions 
of use under which the gyrostabilizer can be employed with profit. Equally 
favorable circumstances of test were established,employing the same tanks and 
skilled crew, similar terrain and equivalent daily maintenance of equipment. 
The crew knew in advance the nature of targets, the exact ranges to be employed 
and the characteristics of terrain to be encountered in each test. 
2. EQUIPMENT AND PROCEDURES: 
a. Nature of Tests 
(1) The relative effectiveness was determined for stationary fire 
and for moving fir© with and without gyrostabilizer against 
the following targets: 
(a) Large, 12* x 12*, vertical panel 
(b) Silhouette of head-on, prone man 
(c) Low, area target to represent a hedge, row of bushes 
and the like. 
(2) The ranges employed were as follows: 
Moving fire at 2 and 10 mph 
with and without gyrostabilizer 
Stationary 
Mean Range 
200 yds. 
500 11 
1000 " 
100 yds, 
*200 " 
250 " 
500 »■ 
* Against large, 12' x 12*, panel only 
b. Firing from the stationary tank was done at the specified ranges. 
The moving fire tests, however, were conducted over zones centered at the 
specified distances, the zones being 50 yards for the 100 yard mean range, and 
100 yards for the others (except in the 12* x 12f panel test at 500 yards which 
employed a 200 yard zone). Tank speeds of 2 and 10 mph were employed, to repre- 
sent respectively, use of tanks with advancing infantry and on reconnaissance or 
* Project No. 21 - ■first Partial Report on Determination of the Sources, 
Magnitude and Costs of Gunnery Errors. Subject; Capacities and Limitations 
of Moving Fire with Gyrostabilizer, dated 24 May 1944. other independent operations of movement. 
(3) With only two exceptions, the unit power field of the T8 
periscopic sight was employed in these tests. 
b. Squipment and Test Facilities: 
(l) Terrain: The tests were conducted at Rolling Fork flange, 
Fort Knox, Kentucky, during April and May 1944. As in the 
previous tests, the ground was essentially flat farm land, 
moderately well drained. In general, the ground was found 
to be more favorable than was the area used in the 75 nan 
gun tests and because of the later date of these tests, 
less trouble was experienced with mud and ruts. 
(2) Targets: For the stationary fire and a limited number of 
moving fire tests, large vertical white panels, 12* x 12', 
with 3* dia.‘ black centers were employed. In the remainder 
of the moving fire runs, low contrast, 0. D. cloth panels 
1 yard high and 6 yards long were used for both the area 
fire (to simulate a hedge, etc.} and fire against the sil- 
houette of the prone man. For the last, there was placed 
in front of the cloth panel a standard composition board 
silhouette of proper dimension, as shown in the charts. 
Locations for the area and silhouette targets were chosen 
in relation to natural features of the terrain to approxi- 
mate well-hidden enemy machine gun or rifle positions. 
Thus, the targets were placed behind tall grass, lines of 
small bushes, etc. 
(3) Tanks: A"he same M4A3 tanks were employed as in the previous 
tests. They were maintained in excellent mechanical condi- 
tion throughout the tests. The coaxial machine gun was care- 
fully adjusted in advance for optimum operation and was so 
maintained during the study. Ammunition was provided with 
one-in-five tracer. 
c. Presentation and analysis of results; 
(l) The results of all tests, firing from the stationary and 
moving tank at the several ranges and against the various 
targets are shown in the form of dispersion plots in Figures 
1 thru 11 and 13 to 15 inclusive. The number of rounds fired 
which varied from 100 to 500, and the number of hits on the 
target are indicated in each case. The position of each hit 
is indicated in relation to horizontal and vertical coordi- 
nates. 
(2) The dispersion patterns were, so far as possible, subjected 
to statistical analysis, as in the previous report, and 
expressed in terms of horizontal and vertical standard devia- 
tions. Owing to the high proportion of misses in some of the 
tests, however, it was necessary in the analysis to make certain assumptions concerning the distribution of the missing 
rounds in relation to the target* This was done in such a way 
that normal probability distributions were secured* Other 
methods of analysis or means of presenting the results will be 
noted in the discussion of results* 
3* RESULTS 
a. Stationary fire: 
The relative precision of stationary fire is demonstrated by 
the plots in Figs. 1, 2 and 3 and the dispersion values in Table 1, The angular 
dispersion was approximately equal at 200 and 500 yds. but was increased some 50$ 
in each direction at 1000 yds. range. The observed values are in substantial 
agreement with firing table data for the Browning Machine Gun. The concentration 
of fire is great at 200 yds. and remains high at 500 yds. Against a rectangular 
area 26" x 19" (extreme dimensions of prone man silhouette), the probability of 
hits vary from practically 100$ at 100 yds. range to 37$ at 500 yds. 
b. Moving fire, with and without gyrostabilizer. large panel target. 
The results of moving fire with and vdthout the gyrostabilizer and with tank 
speed of 10 mph are shown for ranges of 200 and 500 yds, in Figs, 4 to 8, 
inclusive. Comparisons are made at 200 yds. with the periscopic sight M4 (M38 
telescope) and at 500 yds. with the unit power T8 sight. 
Owing to the fact that there were substantial numbers of misses, 
particularly at 500 yards, it was not possible to calculate MPI and Cfx and O'y 
directly. They were therefore determined graphically on probability paper, the 
distribution of the missing rounds being assumed so as to give a normal probability 
curve. Thus, the following assumptions were made with respect to the misses in 
each teat: 
Range, yds. Sight Gyro Assumed distribution of misses 
200 UU Yes Equally on left and above target 
200 M4 No Equally all around target 
200 T8 Yes All on left of target 
500 T8 Yes Equally all around 
500 T8 N© Equally all around 
TABLE I 
Dispersion of Hits in Stationary Fire 
Coaxial Machine Gun - Cal. 30 Ball 
Ko, Rounds 
•;s'-4 
DISFBRSIOI. 
os 
Oy 
503> Area 
90% Area 
Range 
Fired 
,0n Target 
Feet 
7* 
Feet 
rh 
Sq. Ft. 
Sq. Ft. 
200 
100 
100* 
Q.44 
q.73 
0.54 
o.?o 
1.05 
3.80 
500; 
■too 
100 
1.00 
0.56 
1.15 
0.76 
5.10 
18.4 
XGOCb 
200 
133 
4.3 
1.43 
4*6 
1.53 
87.0 
317.0 
* Target 6* x 61, number of hits 89. Estimated 100$ hits on 12* x 121 target. The resulting dispersion values, in terms of standard deviations and 50£ and 
90% areas of probability, are given in Table 2. As compared with moving 
fire with 75 mm gun, the dispersion of MG fire is greater, owing in part 
to the lower accuracy of the weapon and, in addition, to the fact that the 
gunner is less critical of his aim because of the more rapid action of the 
gun and greater quantity of ammunition which is available. Calculated pro- 
babilities of hits within a rectangular area 26° x 19" (extreme dimensions of 
prone man silhouette) are compared for stationary and moving fire, with and 
without the gyrostabilizer, in Table 3* These are for a tank speed of 10 
mph and are based upon firing against the large exposed panel. The relative 
improvement afforded by the gyrostabilizer over moving fire without the 
stabilizer is evident from the data but of greater practical interest is the 
low probability in either case as compared with that attainable from the 
stationary tank. 
c. Moving fire, with and without gyrostabilizer, prone man target. 
In contrast to the firing tests against the large exposed 
panels, the target in this case was a standard silhouette of a head-on prone 
man. It was located in each test in a selected position which provided 
partial hiding by grass or small bushes and was backed up by an O.D. Cloth 
panel one yard high and six yards long. The tests at a tank speed of 2 mph 
were designed to represent use of the vehicle with infantry and those at 10 
mph to approximate the independent operation of tanks in movement. Results 
of the firing tests, with and without the gyrostabilizer, are presented in 
Figures 9 to 11 inclusive. The number of rounds fired and the number of 
hits on the target and on the panel are given with each plot. 
TABU) 2 
COMPARATIVE DISPERSIONS OF HITS 
Moving Fire With Coaxial M.G., With and Without Gyrostabilizer 
Gyro 
i 
Range 
Sight 
No. 
Hounds 
MPI From 
Target Center, Ft. 
Dispersion 
0 
; 
50% 
Area 
ft. 
90% 
Area 
ft.^ 
Fired 
On Target 
Horiz. 
Vert. 
ft. 
mil 
ft 
mil 
With 
200 
UU 
425 
346 
-0,8 
*2.0 
3.2 
$.3 
2.7 
4.5 
38.0 
135.0 
Without 
200 
m. 
500 
37$ 
-0.7 
♦0.8 
3.7 
6.2 
4.7 
7.8 
76.0 
265/>0 
With 
200 
T8(lx) 
500 
406 
-0*8 
-1.0 
3.5 
$.8 
1.3 
2.2 
20.0 
With 
500 
T8(1jc) 
500 
226 
-0.3 
-0.3 
5.9 
3.9 
5.9 
3.9 
358.0 
Without 
500 
T8CU) 
500 
88 
-1.5 
-1.5 
8*4 
5.6 
8.4 
5.6 
3L0.0 TABLE 3 
Probabilities of Hite on Head-On Man Target 
Comparison of Moving Fire With and Without Gyrostabilizer 
And Stationary Fire. 
Coaxial Machine Gun 
Range 
Sight 
Stationary 
Fire 
Moving Fire 
With Qyro 
Without Gyro 
200 yds 
M4 
85* 
6% 
3% 
200 yds 
T 8 
85+1 
— 
12% 
500 yds 
T8 
37% 
2% 
0.9% 
It will be observed that the hits on the 6 yard panel were distri- 
buted horizontally in a normal fashion with relatively high concentration in 
the area around the silhouette target and decreasing numbers of hits laterally. 
This indicates that the misses were primarily distributed above and below the 
panel and were so assumed in the graphical analysis of the dispersions. The 
results are given in Table 4* From the standard deviations thus determined, * 
the probabilities of hits within a 26rt x 19" area (which includes the 
silhouette target) have been calculated and are presented in the table together 
with the actual percentages of hits obtained on the targets in the several tests. 
The actual percentage hits are plotted against range for moving fire, with and 
without the gyrostabilizer, at 2 and 10 mph, in Figure 12. For comparison, the 
calculated probabilities of hitting within the same target area are also pre- 
sented for stationary fire. The comparative results are striking and indicate 
the low order of relative precision of moving fire. 
4 
Since the machine gun is commonly fired in bursts of 5 to 8 rounds, 
one may, for the purpose of discussion, consider a 20* probability of hits 
(5 rounds per hit), as an acceptable precision of fire. Moving fire with the 
gyrostabilizer meets this criterion at a tank speed of 2 mph and ranges up 
to 250 yards. The standard is also approximately met at the same speed and 
ranges without the stabilizer. Beyond 250 yards range there is a rapid 
deterioration of precision. At 500 yards, the number of rounds per hit has 
increased to 20 or more and no advantage is seen in the gyrostabilizer over 
firing with the non-stabilized gun. The precision of fire was further re- 
duced with a tank speed of 10 mph, requiring 7 to 10 rounds per hit with 
the stabilizer at ranges up to 300 yards and 50 or more rounds at 500 yards. 
- 5 - TABLE 4 
Comparative Dispersions of Hits 
Moving Fire with Coaxial M*G., with and without Gyrostabilizer 
Target: Silhouette of Head-On Prone Man 
~ 
With Gyrostabilizer 
Without Gyrostabilizer 
Jiv cUl IVcuigv 
o: 
O? 
% Hits on Tfet, 
crx 
% Hits on Tgt. 
rt. 
Ft. | £ 
Obs. 
* Car 
p 1 
Ft. I i 
ObiTT“ 
'T'Cal. 
Tank S] 
peed: 2 MPH 
100 
1.7 
5.7 
1.0 
3.3 
22.0 
29.0 
1.5 
5.0 
1.2 
4.0 
28.0 
28.0 
250 
2.0 
2.7 
0.9 
1.2 
18.0 
27.0 
1.4 
1.9 
1.6 
2.1 
12.4 
23.0 
500 
- - 
4.0 
2.7 
3.0 
2.0 
2.4 
2.0 
3.5 
2.3 
3.0 
2.0 
0,6 
0.4 
Tank Speed; 10 MPH 
100 
3.1 
io.3 
1.8 
6.0 
9.0 
10.0 
2.5 
8.3 
1.0 
3.3 
6.0 
21.0 
250 
2.9 
3.9 
1.3 
1.7 
6.8 
14.0 
2,8 
3.7 
3.3 
4*4 
k.S 
6.U 
500 
7.8 
5.2 
4.0 
2.7 
loO 
1.9 
7.8 
5.2 
4.0 
2.7 
1.8 
1.9 
It may be useful to evaluate the probabilities of hits obtained in moving 
fire in relation to the rates of fire that can be maintained during an advance. 
The number of rounds fired per 100 yards travel in the present tests averages!. 
88 with and 71 without the gyrostabilizer. Using these average values, the 
number of individual prone-man targets which could be hit during a 100 yard 
advance has been calculated from the data given in Table 4 and the results are 
tabulated for each test in Table 5, ♦ 
TABLE 5 
Expected Number of Prone Man Targets Hit During 100 Yard Advance 
Moving Fire, Coaxial Machine Gun 
Mean 
Range 
Yards 
With Gyrostabilizer 
Without Gyrostabilizer 
From 
Obs. Data 
Cai^rob. 
0b£°8.ta 
Cal^rfrob. 
Tank Speed: 
2 mph 
100 
18 
25 
20 
20 
250 
17 
24 
9 
16 
500 
3 
2 
5 
0o3 
Tank Speed: 
10 mph 
100 
5 
9 
2 
15 
250 
7 
12 
4 
5 
500 
1 
2 
hi 
1.3 d. Moving fire, with and without gyrostabilizer. area targets. 
The purpose of these tests was to determine the concentration 
of fire that can be maintained from the moving tank agAinst targets of some 
length and having no specific point of aim. Cloth panels, 0, D. in color 
and 6 yards by 1 yard in dimension, were located at selected points of 
natural terrain to simulate hedges, fence lines and the like. The gunner 
was instructed to direct his fire over the entire length of the target. Again, 
tank speeds of 2 and 10 mph were employed in the tests and comparative per- 
formance with and without the stabilizer determined. The results are presented 
graphically in Figs. 13 to 15 > inclusive. Owing to the irregularity in the 
horizontal distribution of hits, no statistical analysis of results is 
attempted. In Table 6, the actual concentrations of hits are tabulated per 
foot of target length (average) for the entire panel. Concentrations for the 
same bands, based upon the vertical dispersion obtained in the stationary 
fire tests, are also given for comparison. These tabulated data are plotted 
in Figs. 16 and 1? for the 3 feet and 1 foot bands, respectively. It will be 
observed that the concentrations of hits were approximately the same in 
stabilized fire at the two tank speeds and also at 2 mph without use of the 
gyrostabilizer. At a speed of 10 mph without the stabilizer there was a loss 
of concentration of approximately one-third. 
TABLE 6 . 
Concentration of Hits on Area Target 6 Yds.Long 
Coaxial Machine Gun 
Number of Hits per Foot Length Per 100 Rds.Fired 
For Bands 1, 2 and 3 feet in Height 
Height 
©f 
TYPE OF FIRE 
Stationary 
With Gyrostabilizer 
Tank Speed 
Without Gyrostabilizer 
Tank Speed 
Band 
(calculated) 
2 mph 
10 mph 
2 mph 
10 mph 
RANGE: 100 yds. 
1 foot 
4.7 _ 
1.82 
2.10 
2.90 
1.31 
2 feet 
5.5 
3.23 
4.00 
4.44 
2.39 
3 feet 
5*55 
4.27 
4*32 
4*95 
RANGE: 250 yds. 
1 foot 
3.1Q 
1.82 
1.64 
1.60 
1.02 
2 feet 
4.95 
3.17 
2.68 
2.87 
1.71 
3 feet 
5±45 
3.93 
3.67 1 
8 
2.07 
RANGE: 500 yds. 
1 foot 
1.67 
1.05 
P.96 
0.82 
0.57 
2 feet 
3.10 
1.84 . . 
1.82 
1.44 
lo07 
3 feet 
4.28 
2.17 
2.38 
1.90 
1.46 4. DISCUSSION: 
It is recognized that the results obtained in this study do not 
represent a complete evaluation of the capacities and limitations of machine 
gun fire from the moving tank. Compared -with the wide variety of targets which 
may be encountered in combat, those employed in these tests are of limited sig- 
nificance, It is probable, however, that sufficient data are presented to show 
the order of magnitude of precision of fire which may be expected under favorable 
operating conditions, regardless of the exact nature of the target. 
In many of the tests, especially at 2 mph, the gyrostabilizer failed 
to show any advantage over the non-stabilized gun. Undoubtedly this resulted 
from operation on superior terrain and is not to be expected when moving over 
rough ground. It must be pointed out, however, that the improvement in compara- 
tive performance in the latter case would be accompanied by an absolute reduction 
in precision of fire with the gyrostabilizer as well as without. The results 
presented here suggest that no such reduction could be accepted. FIG. I 
OBSERVED DISPERSION-STATIONARY FIRE 
M4A3 MED. TANK, CAL. 30 COAXIAL M.G., M 4 SIGHT 
RANGE-200 YARDS 
ROUNDS FIRED-100 
FIG. I FIG. 2 
OBSERVED DISPERSION-STATIONARY FIRE 
M4A3 MED. TANK, CAL. 30 COAXIAL M.G., M 4 SIGHT 
RANGE-500 YARDS 
ROUNDS FIRED-100 
FIG. 2 FIG. 3 
OBSERVED DISPERSION - STATIONARY FIRE 
M4A3 MED. TANK, CAL. 30 COAXIAL M.G., M 4 SIGHT 
RANGE-1000 YARDS 
ROUNDS FIRED-200 
FIG. 3 FIG. 4 
OBSERVED DISPERSION 
MOVING FIRE WITH GYROSTABIL1ZER 
M4A3 MED. TANK, CAL. 30 COAXIAL M.G., M 4 SIGHT 
RANGE-ZOO YARDS 
ROUNDS FIRED -425 
ON TARGET - 346 
FIG. 4 FIG. 5 
OBSERVED DISPERSION 
MOVING FIRE WITHOUT GYROSTABILIZER 
M4A3 MED. TANK, CAL. 30 COAXIAL M.G., M 4 SIGHT 
RANGE-200 YARDS 
ROUNDS FIRED-500 
ON TARGET - 375 
FIG. 5 FIG. 6 
OBSERVED DISPERSION 
MOVING FIRE WITH GYROSTAB1LIZER 
M4A3 MED. TANK, CAL 30 COAXIAL M.G., T8(IX) SIGHT 
RANGE-200 YARDS 
ROUNDS FIRED-500 
ON TARGET -406 
FIG. 6 FIG. 7 
OBSERVED DISPERSION 
MOVING FIRE WITH GYROSTABILIZER 
M4A3 MED. TANK, CAL. 30 COAXIAL M.G., T8(IX) SIGHT 
RANGE-500 YARDS 
ROUNDS FIRED-500 
ON TARGET - 226 
FIG. 7 FIG. 8 
OBSERVED DISPERSION 
MOVING FIRE WITHOUT GYROSTABILIZER 
M4A3 MED. TANK, CAL. 30 COAXIAL M.G., T8(IX) SIGHT 
RANGE-500 YARDS 
ROUNDS FIRED-500 
ON TARGET - 88 
FIG. 8 FIG. 9 
OBSERVED DISPERSIONS- MOVING FIRE WITH AND WITHOUT GYROSTABILIZER 
M4A3 MED. TANK, CAL. 30 COAXIAL M.G. 
RANGE-100 YARDS 
2 MPH - WITH GYROSTABILIZER 
NO. ROUNDS: FIRED = 100, ON PANEL =90; IN TARGET =22 
2 MPH - WITHOUT GYROSTABILIZER 
NO. ROUNDS: FIRED = 100 ; ON PANEL =78; IN TARGET = 28 
PANEL HEIGHT-FEET 
10 MPH - WITH GYROSTABILIZER 
NO. ROUNDS: FIRED = 100 i ON PANEL = 71 • IN TARGET = 9 
10 MPH WITHOUT GYROSTABILIZER 
NO. ROUNDS: FIRED = 100 : ON PANEL = 64 ■ IN TARGET = 6 
PANEL LENGTH-FEET 
FIG. 9 FIG. 10 
OBSERVED DISPERSIONS - MOVING FIRE WITH AND WITHOUT GYROSTABILIZER 
M4A3 MED. TANK, CAL. 30 COAXIAL M.G. 
RANGE-250 YARDS 
2 MPH - WITH GYROSTABILIZER 
NO. ROUNDS; FIRED =250- ON PANEL = 229; IN TARGET = 45 
2 MPH - WITHOUT GYROSTABILIZER 
NO. ROUNDS: FIRED = 250 * ON PANEL = 163 • IN TARGET = 31 
PANEL HEIGHT-FEET 
10 MPH - WITH GYR0STAB1LIZER 
NO. ROUNDS: FIRED = 250 ■ ON PANEL = 182, IN TARGET = 17 
10 MPH WITHOUT GYROSTAB1L1ZER 
NO. ROUNDS: FIRED = £50; ON PANEL =87; IN TARGET =■ IE 
PANEL LENGTH-FEET 
FIG. 10 FIG. II 
OBSERVED DISPERSIONS - MOVING FIRE WITH AND WITHOUT GYROSTABILIZER 
M4A3 MED. TANK, CAL. 30 COAXIAL M.G. 
RANGE-500 YARDS 
2 MPH - WITH GYROSTABILIZER 
NO. ROUNDS: FIRED =500; ON PANEL = 207; IN TARGET = 12 
2 MPH - WITHOUT GYROSTABILIZER 
NO. ROUNDS: FIRED =500, ON PANEL = I87; IN TARGET = 3 
PANEL HEIGHT-FEET 
10 MPH - WITH GYROSTABILIZER 
NO. ROUNDS: FIRED = 500, ON PANEL= 100, IN TARGET = 5 
10 MPH WITHOUT GYROSTABILIZER 
NO. ROUNDS: FIRED = 500. ON PANEL = 89 ; IN TARGET = 9 
PANEL LENGTH-FEET 
FIG. II FIG. 12 
OBSERVED PERCENTAGE HITS ON HEAD-ON PRONE MAN TARGET 
MOVING FIRE IN RELATION TO RANGE WITH AND WITHOUT GYROSTABIL1ZER 
M4A3 MED. TANK, CAL. 30 COAXIAL M.G 
NO. RDS. NECESSARY FOR I HIT 
PERCENT HITS ON TARGET 
RANGE - YARDS 
FIG. 12 FIG. 13 
OBSERVED DISPERSIONS MOVING FIRE WITH AND WITHOUT GYROSTABILIZER 
M4A3 MED. TANK, CAL. 30 COAXIAL M.G. 
RANGE - 100 YARDS 
2 MPH - WITH GYROSTABILIZER 
NO. ROUNDS; FIRED = 150; ON PANEL = 115 
2 MPH - WITHOUT GYROSTABILIZER 
NO. ROUNDS: FIRED = 100; ON PANEL = 89 
PANEL HEIGHT-FEET 
10 MPH - WITH GYROSTABILIZER 
NO. ROUNDS: FIRED = 100; ON PANEL = 78 
10 MPH WITHOUT GYROSTABILIZER 
NO. ROUNDS: FIRED = 100; ON PANEL= 55 
PANEL LENGTH-FEET 
FIG. 13 FIG. 14 
OBSERVED DISPERSIONS MOVING FIRE WITH AND WITHOUT GYROSTABILIZER 
M4A3 MED. TANK, CAL. 30 COAXIAL. M.G. 
RANGE-250 YARDS 
2 MPH - WITH GYROSTABILIZER 
NO. ROUNDS; FIRED = 250; ON PANEL=177 
2 MPH - WITHOUT GYROSTABILIZER 
NO. ROUNDS: FIRED =250; ON PANEL = 61 
PANEL HEIGHT-FEET 
10 MPH - WITH GYR0STABIL1ZER 
NO. ROUNDS: FIRED =250, ON PANEL = 165 
10 MPH - WITHOUT GYR0STABIL1ZER 
NO. ROUNDS; FIRED = 250, ON PANEL = 93 
PANEL LENGTH-FEET 
FIG. 14 FIG. 15 
OBSERVED DISPERSIONS MOVING FIRE WITH AND WITHOUT GYROSTABILIZER 
M4A3 MED. TANK, CAL. 30 COAXIAL M.G. 
RANGE-500 YARDS 
2 MPH - WITH GYROSTABILIZER 
NO. ROUNDS: FIRED = 500; ON PANEL = 196 
2 MPH - WITHOUT GYROSTABILIZER 
NO. ROUNDS: FIRED =500; ON PANEL = 171 
PANEL HEIGHT-FEET 
10 MPH - WITH GYROSTABILIZER 
NO. ROUNDS; FIRED =500; ON PANEL = 215 
10 MPH - WITHOUT GYROSTABILIZER 
NO. ROUNDS: FIRED = 500; ON PANEL = 132 
PANEL LENGTH-FEET 
FIG. 15 FIG. 16 
CONCENTRATION OF HITS ON AREA TARGET 6 YARDS LONG 
IN RELATION TO RANGE 
COMPARISON OF STATIONARY FIRE AND MOVING FIRE WITH 
AND WITHOUT GYROSTABILIZER AT 2 MPH AND 10 MPH 
HITS IN A HORIZONTAL BAND 3 FT. HIGH 
EXPRESSED AS PERCENT POSSIBLE 
STATIONARY 
MOVING, WITH 
GYROSTABILIZER 
MOVING, WITHOUT 
GYROSTABILIZER 
RANGE -YARDS 
FIG. 16 FIG. 17 
CONCENTRATION OF HITS ON AREA TARGET 6 YARDS LONG 
IN RELATION TO RANGE 
COMPARISON OF STATIONARY FIRE AND MOVING FIRE WITH 
AND WITHOUT GYROSTABILIZER AT 2 MPH AND 10 MPH 
HITS IN A HORIZONTAL BAND I FT. HIGH 
EXPRESSED AS PERCENT POSSIBLE 
STATIONARY 
MOVING, WITH 
GYROSTABILIZER 
MOVING, WITHOUT 
GYROSTABILIZER 
RANGE - YARDS 
FIG. 17