DTIC ADB190438: Experiments to Determine the Effects of Different Flash Suppressor Designs on Accuracy of an F89 Light Machine Gun

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ADB190438
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DSTO notice, R9607/7/9 ptl,20 Apr 1999
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AD-B190 438
I*T. CU_
Experiments to Determine the
Effects of Different Flash Suppressor
Designs on Accuracy of an F89
Light Machine Gun
C. Wachsberger
"te " Distribution authorized to Don Components only
iibe refers to
Embassy of Australia
Attn: 4oap Bliss
Head. Pub, Sec. -Def/Sci.
1601 Massacvusets Ave N
Washington, DC 20036
H~,q/ (,'N :(cid:127) JJlFL, ';II (cid:127)I" /)~l '
A'(N.111 Jd1 1I 4 Y' I-A R AlI
A6 94-32089
1!ll ii ý iI R T HUTii ' li
D E P ARTMENT o IF D E r E N C E
DEFENCE SCIENCE AND TECIHNOLOGY ORGANISNAION
Experiments to Determine the Effects of Different (4
Flash Suppressor Designs on Accuracy of an F89
Light Machine Gun
C. Wachsberger
Aeronautical and Maritime Research Laboratory
ABSTRACT
General Document
*
Tests were performed to determine the accuracy of an Australian 1:89l ight machine gun
having barrels fitted with or without flash suppressors. The results of these experimnents
are presented irs this report. It was observed that tie addition of a flastt suppressor fromn
a MAG 58 macline gun can reduce the size of mean radius dispersion by as much as
41% over an original Mirinri flash suppressor and 35% over none being fitted. It
appears that when using standard taper-ended Mininri barrels 19% of this improveerent
can be attributed directly to the mass of the MAG 58 flash suppressor but that this mass
has no apparent effect on accuracy wher using heavier P89 barrels.
It was concluded that gasdynamic effects due to flash suppressor sesign may have a
significant role, in weapon accuracy and merit further study.
RELEASE LIMITATION
Distribution additiorul to the initial list is lisrited to qualified officerso f tire Defence Departrsert
and theD efence Forceo f Australia, UK, USA,C anada aordN ew Zealand. Other requests shhtat
be referred toC hief, Explosives Ordnance Division AMRL.
DSTO-GD-0003
Df1PAHT MENT or DC1:ENCE
DEFENCSEC IENCAEN I TECiNOLOOGRyG ANiSA[iON
DTIe QUALITYh i:m:L-
'Cr•
R0
Published by
DSTO Aeronautical and Maritime Research Laboratory
GPO Box 4331
Melbourne Victoria 3001 Australia
Telephone: [phone]
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© Commonwealth of Austratia 1994
AR No. 008-607
June 1994
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Aeronautical and MaritimeR esearch Laboratory. 0
Contents [
1. INTRODUCTION S
2. EXPERIMENTAL 6
3. RESULTS 8
3.1 F89 barrel 8
3.2 Minini barrel 11
3.3 Thick walled prooft ype barrel 20
3.4 New F89 barrel 20
4. DISCUSSION 22
5. CONCLUSIONS AND RECOMMENDATIONS 25
I
6. ACKNOWLEDGEMENTS 25
7. REFERENCES 25
APPENDIX I Oplical Proximity Swilch -OperatingP rinciples 26
0
* 0
Experiments to Determine the Effects of
Different Flash Suppressor Designs on Accuracy
of an F89 Light Machine Gun
1. Introduction
In 1989 the Engineering Development Establishment conducted, on behalf of the
Small Arms Replacement Project (SARP), an evaluation of the PN Minlnd (now
referred to in tfIe Australian inventory as the F89) light machine gun to ascertain
its level of acceptance into Australian service. In an isolated test in March 1989 it
was found that significant reductions in the dispersion size of 5-round bursts were
achieved when the -. ginal Minini flash suppressor was replaced with a flash 0
suppressor from eitner the 1:88r ifle jr from a MAC 58 general purpose machine
gun I 11. It was not knownr whether tie improvement in burst dispersion was due
to the increase in mass thereby reducing vibration to the barrel assembly, an
increase in the gas dynamic erficiency associated with the flash suppressar vent
design, or a combination of both.
Army subsequently tasked MRL to conduct experiments on an F89 light
machine gun to determine target dispersion when titled with either IN Ilelgiani
Miniini Iv.rr,.:s or Australian barrels built at the ADI facility at Lithgoiw. Tests
were zivy,(cid:127),td to determine the effect of different flash suppressors (FS) on
accuracy, and this included the standard pattern Minimii S, a MAG 58 lS, or no
IS at all. tphotographs showing these two PS designs are given in figures I and 2.
Figure 1: Standard Minimi fladi suppressornr
1S
* 0
~Figure
* 2: AilACS Sflasfsi uppressor
2. Experimental
~A ~spaecni~rylte t fixture wasc onstructed to rigidly support the A7tw ea'ion such that
* movement detecteda t them uzzle could only be associatewd itthi 'ratioiss si
barrel position andr iot of tie whole gun Itigure, 3).
0
Whenw iirk conmmenciends threp roject,i t was decidedi tl iszmcl ssitorniisisn,
could heg ained it, fore achr iiuindt ired friimt he weaysis..ic rs.i.......Issbled
drawin hetwecii [lie mosvenient if Csieg iuni riuzzle aiid [lit, lositisoso h
inipact at the target.T o iteterinre ttsis.a ii iiptical pro-iiis y wilidhw csi
co Arcweh iche nabledu miuezdi eflection to hve aui enisi iii bllui tif,,ols
~an~dh ~oi~rizponritaipln lanceisp( figlueres 4 1.A complete description oh ti nivl-ictimig
* sit the taiiinil ihxic cziliounclid Appeii0,is1I si11io-11x, is,
0
threp roximity switches were ted into a 2-c~hannedli gital transient recoeder
(Le Cray type 9410). A hardcopy ot tire barrel motion traces coutd be obtoined
frons a graphics plotter coninected ts the recorder. A pesbe which detects the
- ionised propelling gases was used to determine tire precise moment the projectile
tell the barr.el.
Pigire. 4: Ita-r0 rot-ize.sho optical troatotttp xreitclrc.
~~I ceox.ipr ernioidetiut c'tlirseigditi Iii test thre peratiot i tttI, re tr.In..o iitsvitIi vior
- rising antsx SARI' triallsil M minliingh rtn ralirrits gunx( receivertno
FN tXtlttbb held at tWOt. As Iris Pilirw astin a very worirs tate ,i weal ..r. ...
siuited lto( liret ask (receiver to. )IIN8 309)) along with a new Minims barrel (trart
oni9. .348420),.wa orn hut sopprisedlymsill usable F89b arrel (part nor.A M tilI(533.2
prirsuced at API l~hgowl atid several hundred moondso ft Australian miade
5-%o,t o s-I5toni IIIb all anmounilitin (dated API 5-12-88)w ere ribtained] fni
All tests sworet perfrormeda t the 601to indroir grin tiring rouge tacility lrcarted at
li01) Salisbury. IThei ndootr tacility, despite being somnewhtaltm itest Ili ranrge, sditd
rave bhea dvanitage oft protvidinig art enreironmtuent where thret liglrtpattr Ii tsre
projectliles was tttt altecrert byc ross wvinids.I thel orcatiotnat id tdetrtittcattt -f
rouirds as they impacted Itot arget area was perforrmedss ting.a gri1t praterrr artuti
videoscamoerast.i re grid pattern consistedt if a series tnfs qoare seguiretutcsa cti
ItDOm intw ide by I111m) itt high. liacli target was 6.00m ix ill wirtti by 8t0t Minii ni
height. A video camera arid light usourcew ere positioned Ili such a way that thre
target coulrt ho viewed with,m ininual dislotritii hmorto tfv tire litre If tIre. Asai
24
0
additional precaution the video camera was protected by an aluminium box fitted
with a polycarbonate viewing window to prevent damage from wood and metal
splintoeresm anating fromnth e project ile catchrerT. hoc ameraw as connectedto a
VHS video recorder (VCR) and monitor. The VCR was set to record during a
filing. On single-frame playback the location and order of impacts could be
simply visualised, and the approximate positions noted. Measurements were
later taken with a ruler and the coordinates of each shot in a series thusu
determined. The target was repaired with paper adhesive tape before the next
firing.
The tabling of bullet dispersion results easulated the procedure used at EDE [ 1 .
The impact position of each 5-round group was noted and the mean coordinate
position calculated (herein known as its mean point of impact or MPil). Thre
maximum spread in both horizontal (X) and vertical (Y) planes and the extreme
spread (the distance between the two furthermost impacts) were also determined
and standard deviations (SD) calculated. The spread provides a guide to the
overall shape of the distribution. Morn helpful however to the measurement of
dispersion is the calculation of mean radius (MR) which is defined as the average
radial distance of the impacts relative to the MPi is a given burst. Tihe standard
deviation is a guide to the consistency with which the MR is maintained. Finally
the average, standard deviation, minimum and maximum figures would be
calculated for each firing serial (repeated bursts of a given test configuration).
The gun support rig was adjusted in such a manner that when the Minixi barrel
was used without any flash suppressor devices fitted, the mean distributin of a
5-round burst would be about the centre of the grid pattern.
Early esperianeots were performed by firing belts containiag 5-rounds of tinketd
ammunition. tI sublsaaquent testhag an M 16-type magazine loaded with 5-rounds
w"eaffse cutsse d as it simplified the firing procedure and appeared to have no adrvesse
a run lesarties rr accuracy. All testing was performed with tIre .orrne
gas part configutrert iil tire "normat l" , ie msaximum, vented position
3. Results
3.1 F89 barrel
tests mere l rrinedaa slt11 flit' 1310w eapon (feceaver no 1; 0109t 11. l1 1 .ta.r.. .a.
Australian stte f1F9b trret (parot is AM fl(i33-2). Tbis barrel las s.,rare ,oavlc.oa-
visual atittercirces larirn ateI k-gnasa (Miaanafl caauasfeirpar. 1 tar PitSt arsal as ahh]
sids'd lbrougltoaut ifs lagtlh whIen-as thr FN bartel taier.rs towards the aantrl
froam about 21/rsfs tal Irta bIrrea ta-gta Irali r'tlc 'arianr is hrs-radtid (tight-htaa
thread) ta accept the direr t tittiag ar a MAt(; Si fltatfiuppreer, t fer'.afst ' I;N
barrel has a lefl-haua thread wintlt, siautlie diameter thao flat 1:895 threadt assi t a
da-signed to cc'a l lhtt. a.t .a .i..lly ebaife atiri flash safa inr flaI r I,, s.grtlh t-
aima d;ffer ard aliasw ould lresuanably ee ffhcvt aarftlhaet' tiarrl aaa'aaas
charaartermstics. 'agauta5 hoiw%t he diitrenrt barril and f1ias..u(cid:127) flfaae'
a-a ambisnaasIiaan
80
[0
*
Figure 5: Mininda ad F:89b arrels
When fired this combinatiotn produced th~e large( impact distribution is shown in
Table 1:
TAULE 1. Target dispersion at 60 faelres itsing a woarAnD I-L barrel
(5-roal bursts)
ARRANGEMENT SPREADr aDIISPEIMION (am
X Y Extre, SID, SDy K4 RS
NO FLAS;I IIIne P'La"l () D-iveaallotl n U(cid:127)ha.iu It(cid:127)t'a"Id
SUPl I. FSSOR - D111htl-a
A...v.. c 178 5.7. 6... 102 ... .1821 u2"
_SWdD eviation_ 5 8(. 152 25 7 12 0
Minimtum 350 38tU M1 136 135 171 91
MaxuL .475 5 754 192 212 _126 180
MINIMFI ILAS11
SUIPPRIESRS.O
Ave-a e 301 7 574 124 230 201 130
St.Deviatn 122 --- 07- 107 (cid:127)38 5 49 25
Mlitlnla. 200 435 442 93 ]58 1.42 93
WMaxiun 475 60 767 175 273 26 17
MSUAIG,[5, R8 FFLrSAOSI-II
4 13URSTS
Std D~evwia 1ion Z241 -145 62 102I
Mnmm 23N56 il1u l 71.315 488131 214071 2590- 6 3168p -711