Post on 23-Apr-2020
Available
Medium Caliber
Barrel life improvementsNDIA Guns & Ammo
Panama City FL
15-18 April 2002
Presented by: Bob Waterfield
• M242 barrel life history• Barrel life comparison test data
• MK44 • M242 • 27mm
• Test result summary• Comments• Availability status
Outline
M242 25mm Automatic Gun
05000
1000015000200002500030000
M79
2
3HE
to
1AP
3AP
to
1HE
M91
9
M79
1
M91
0
Old
M91
9(H
ES
9053
)
Ammo Types
Ro
un
ds
of
Bar
rel L
ife
NitridedChrome Plated Future High
Performance Ammo
2600KFlame Temp
3000KFlame Temp
3600 + KFlame Temp
^ REQUIREMENT ^
MK44 test schedule
A mixture of SS, 3 round & 5 rounds bursttotaling 198 rounds in 27.5 minutes
and cool to ambient
• 66 rounds in 2.5 minutes• 10 minute cool
• 66 rounds in 2.5 minutes• 10 minutes cool
• 66 rounds in 2.5 minutes
30mm MK44 barrel BG-10 results
Nitride bore at 5,000 rounds
Wearout Curve
Chrome bore at 21,000 rounds
30.0
30.1
30.2
30.3
30.4
30.5
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
BG-10 Position
Bo
re D
iam
eter
(mm
)
Forcing Cone Erosion vs. Rounds Fired
204.0 mm wearout limit
5,500 round lifeMK44 Nitride
21,000 rounds firedMK44 chrome
25,000 + round lifeMK44 chrome
projected
190
195
200
205
046
113
1321
6630
7839
3047
1155
358,0
218,9
039,7
5510
,607
11,45
912
,311
13,16
314
,015
14,86
715
,949
16,80
117
,65318
,505
19,35
720
,209
21,04
222
,000
23,00
024
000
2500
0
Rounds Fired
Dis
ttan
ce t
o 3
0.37
5mm
dia
met
er
M242 test schedule
A mixture of SS, & 10 rounds bursttotaling 300 rounds in 34 minutes
and cool to ambient
• 150 rounds in 2 minutes• 30 minute cool
• 150 rounds in 2 minutes
24.8
24.9
25
25.1
25.2
25.3
25.4
25.5
25.6
25.7
25.8
25.9
26
26.1
26.2
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
BG-10 Position
Bo
re D
ia. (
mm
)25mm M242 barrel BG-10 results
4,500 round life Nitride bore
6,500 round life US Army Chrome
Wearout Curve
Boeing Chrome at 6,500 rounds
Boeing Chrome at 14,000 rounds
25
25.2
25.4
25.6
25.8
26
26.20
774
2173
3416
4659
6045
7328
8591
9834
1111
7
1238
0
1334
3
1391
6
1480
0
1620
0
1760
0
1880
0
2000
0
Rounds Fired
Bo
re D
iam
eter
(m
m)
Position 1 Ø (@158mm) vs. Rounds Fired
Wearout limit for position one4,500 round lifeNitride bore
6,500 round lifeUS Army chrome
14,000 rounds firedBoeing chrome
20,000 + round lifeBoeing chrome
projected
140
145
150
155
1600
774
2173
3416
4659
6045
7328
8591
9834
1111
7
1238
0
1334
3
1391
6
1480
0
1620
0
1760
0
1880
0
2000
0
Rounds Fired
Dis
tan
ce to
25.
99m
m d
iam
eter
Forcing Cone Erosion vs. Rounds Fired
156.5 mm wearout limit 4,500 round lifeNitride bore
6,500 round lifeUS Army chrome
14,000 rounds firedBoeing chrome
20,000 + round lifeBoeing chrome
projected
BK27 test scheduleFour (4) one second bursts of 30 rounds each
totaling 120 rounds in 7.5 minutesand cool to ambient
• 30 round burst in one second• 2.5 minute cool
• 30 round burst in one second• 2.5 minute cool
• 30 round burst in one second• 2.5 minute cool
• 30 round burst in one second
Wearout Curve
Existing Production Barrel at 461 rounds
Boeing Chrome at 941 rounds
Boeing Chrome at 461 rounds
27mm Preliminary test results
M242 25mm Automatic Gun
05000
1000015000200002500030000
M79
2
3HE
to
1AP
3AP
to
1HE
M91
9
M79
1
M91
0
Old
M91
9(H
ES
9053
)
Ammo Types
Ro
un
ds
of
Bar
rel L
ife
NitrideUS Army ChromeBoeing Chrome
Future HighPerformance Ammo
2600KFlame Temp
3000KFlame Temp
3600 + KFlame Temp
^ REQUIREMENT ^
Boeing’s chrome process increases life• Greater than 4x compared to our baseline
nitride.– 30mm MK44 barrels– 25mm M242 barrels
• Greater than 3x compared to existing M242fielded barrels
• Greater than 4x Compared to existingBK27 fielded barrels
Test result summary
• Current fielded M242 barrel does notmeet Bradley MN barrel liferequirement with present ammo mix.
• Boeing manufactured chrome barrels– Exceed MN requirement– Will reduce life cycle cost & logistical burden–Allows for increased performance
(higher flame temp.) propellants.
M242 Comments
MK44 Chrome barrelsAvailability status
MK 44 barrels in production withdeliveries on going for
US NavyUS Marines
Norwegian ArmySwiss Army
Finnish Army
M242 & 27mm AircraftChrome barrels Availability status
MK 242 barrelsProcess established
Awaiting kick off customer
Advanced 27mm Aircraft barrelsProcess established
Ready & waiting for JSFor
Any other Kick off customer