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To: sci-military-moderated@moderators.isc.org
From: psl@interchange.ubc.ca (Paul Lakowski)
Newsgroups: sci.military.moderated
Subject: Re: RHA penetration of 25mm M919 from M242 Bushmaster?
Date: 29 Mar 2002 17:19:53 -0800
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TTK Ciar wrote in message
news:...
> Hello,
> I was wondering if anyone knew what the penetration capability was,
> in RHA equivalence, of the 25mm M919 APFSDS when fired from the M242
> Bushmaster chain gun.American 25mm M919 DU APDSFS-T.
THese are estiamtes based on formula from my files
JANE's AFV Retrofit systems 94-95 reports the projectile mass at 132g
and the muzzle velocity at 1385m/s . JANES Ammunition Handbook
2000-2001 adds: Penetrator mass 96g DU with MV@1420m/s , with a time
of flight to 2000m at 1.56s remaining velocity 1149m/s .The muzzle
velocity was initially 1420m/s, then lowered (different prop) to
1385m/s due to barrel wear issues. Its believe they are introducing
new (German?) propellant to bring it back up to 1420m/s. PRIMEX makes
a similar round with a tungsten carbide penetrator, listed weight as
138g, MV 1420m/s. velocity drop listed as 130mps/km. The cutaway pic
when measured resulted in a penetrator diameter in the 7-8mm range &
approx 100mm long [L/d 13:1]. The volume should be 3.85cc and the
penetrator mass about 71gm suggesting the fins and cap are only about
25gm. The penetrator nose is frustum shaped with a small spike for
attaching the windscreen and the semi infinite conversion should be
+1d@ 0° & +2d @ 60° or + 0.7cm /+ 1.5cm due to the frustum nose shape
The Andersons inputs should be 1.044V[km/s] – 0.71 [L/d] x
1.01[scaling] x 1.24 [subscale DU] and the 60° penetration is a line
of sight penetration.
Muzzle 1385m/s = 0.91 x 10cm + 0.7/1.5cm = 9.8cm ± 1.5cm @ 0° & 10.5cm
± 1.6cm @ 60°
1000m 1255m/s = 0.71 x 10cm + 0.7/1.5cm = 7.8cm± 1.3cm @ 0° &
8.6cm±1.3cm @ 60°
2000m 1125m/s = 0.58 x 10cm + 0.7/1.5cm = 6.5cm± 1cm @ 0° &
7.3cm±1cm @ 60°
3000m 995m/s = 0.41x 10cm + 0.7/1.5cm = 4.8cm± 1cm @ 0° &
5.6cm±1cm @ 60°
Zaloga reports 75mm @ 0° at 1000m, while the above estimate is 78mm @
0° at 1000m , suggesting the above estimates are close .
Also, PRIMEX makes a similar round with a tungsten penetrator and a
projectile mass of 138g, MV 1420m/s and the velocity drop listed as
130mps/km.The volume should work out to 71/17.4 [X27X] = 4cc and given
a 7mm rod diameter I get approximately 105 x 7mm rod or 15:1 L/d .I
assume the rest is the same . The penetrator nose is frustum shaped
with a small spike for attaching the windscreen and the semi infinite
conversion should be +1d@ 0° & +2d @ 60° or + 0.7cm /+ 1.5cm . The
Andersons inputs should be 1.044V – 0.738 [L/d] + 0.05 [ X27X
alloy] x 1.01[scaling] and the 60° penetration is a line of sight
penetration.
Muzzle 1420m/s = 0.80 x 10.5cm + 0.7/1.5cm = 9.1cm ± 2cm @ 0° & 9.9cm
± 2cm @ 60°
1000m 1290m/s = 0.665 x 10.5cm + 0.7/1.5cm = 7.7cm± 2cm @ 0° &
8.5cm±2cm @ 60°
2000m 1160m/s = 0.53 x 10.5cm + 0.7/1.5cm = 6.2cm± 1cm @ 0° &
7cm±1cm @ 60°
3000m 1030m/s = 0.39 x 10.5cm + 0.7/1.5cm = 4.8cm± 1cm @ 0° &
5.6cm±1cm @ 60°
Should offer the same performance as DU M919 APFSDS-T round.