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Subject:
What does the US Army need in a next generation machine gun?
Herald12345
2/20/2008 5:04:22 PM
Or for that matter, what do the experts hewre consider would be achievable improvements in the general purpose machine gun? Since I am not an expert on this subject I'm here to learn. I will ask questions though. Its part of the educating Herald series. Herald
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Herald12345
2/26/2008 5:27:49 PM
A reinforcement-or skeletal ceramic lattice material is formed by forming tubes or layers of the reinforcement material throughout a melt of a bulk-solidifying amorphous metal and solidifying the mixture at a sufficiently high rate that the solid metal matrix is amorphous. Intermixing the seramioc is typically accomplished either by melting the metal and mixing the pieces of reinforcement material into the melt, or by providing a skeleton or sheet of the reinforcement material and infiltration of the molten amorphous metal into the mass. The metal preferably has a composition of about that of a eutectic composition, and most preferably has a composition, in atomic percent, of from about 45 to about 67 percent total. An example of this zirconium plus titanium, from about 10 to about 35 percent beryllium, and from about 10 to about 38 percent total of copper plus nickel using either carbon or silicon or aluminum as a binder.
The skeleton is a specialized nano-structure application.
Some expected applications for the class materials are as electro-magnetic, thermal, or KINETIC
superconductors
.
Herald .
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flamingknives
2/26/2008 5:42:53 PM
What TRL is that at?
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Herald12345
2/26/2008 5:45:36 PM
Contact me at my e-mail.
Herald
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WarNerd
2/27/2008 5:10:23 AM
Multiply all
variable values by approximately 80%
.
Herald
Is that multiply the velocity by 80% (800 mps, 2400 joules/1770 footpounds @ 1500ft), or
is it multiply the energy by 80% (895 mps, 3000 joules/2213 footpounds @ 1500ft)
Also, 7.5 grams is only 115 grains, this is pretty light for a 7mm. A heavier bullet in the 140 grain to 150 grain range is generally recommended.
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Herald12345
2/27/2008 5:56:32 AM
1.
115 grains = 7.45188 g
2. 80% falloff in velocity at the given bullet aerodynamic coeff. should be 1500 METERS, not FEET.
3. Your results should be about 2400 joules @ 800 m/s or 1770 footpounds @1500 meters.
4. If you use an 8.5 gram bullet as you specify
-4250 joules @ 1000 m/s or 3129 footpounds strike after 100 meters with a barrel pressure calculated in the 70,000+ N/cm^2 range or well in excess of 100,000+ PSI.
-at 80% falloff in velocity that is 2720 joules or 2002 footpounds strike @ 1500 meters.
What kind of barrel or combustion chamber material are you going to use that can take that kind of pressure at 10 cycles per second?
Multiply all
variable values by approximately 80%
.
Herald
Is that multiply the velocity by 80% (800 mps, 2400 joules/1770 footpounds @ 1500ft), or
is it multiply the energy by 80% (895 mps, 3000 joules/2213 footpounds @ 1500ft)
Also, 7.5 grams is only 115 grains, this is pretty light for a 7mm. A heavier bullet in the 140 grain to 150 grain range is generally recommended.
???????????????????????????????
Herald
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RockyMTNClimber
That's allot of energy Herald...
2/27/2008 12:52:21 PM
-at 80% falloff in velocity that is 2720 joules or
2002 footpounds strike @ 1500 meters
.<Herald
I'd review those numbers for a light weapon. Even off of a bipod. A 140-150gr bullet is about right for a 7mm infantry rifle so we must have too much juice in the calculus to get 2002 ft.lb. of energy hanging still hanging around at 4500+ feet down range. I do allot of work with 7mm's.
Check Six
Rocky
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Herald12345
2/27/2008 1:17:04 PM
-at 80% falloff in velocity that is 2720 joules or
2002 footpounds strike @ 1500 meters
.<Herald
I'd review those numbers for a light weapon. Even off of a bipod. A 140-150gr bullet is about right for a 7mm infantry rifle so we must have too much juice in the calculus to get 2002 ft.lb. of energy hanging still hanging around at 4500+ feet down range. I do allot of work with 7mm's.
Check Six
Rocky
8.5 grams is approximately 131 grains. Bullet is a pointed [as in sharp-nose] boattail [rearmass concentrated] with a fairly sharp ogive to reduce drag. I'm confident, Rocky. 20% velocity falloff at 1500 meters is based on this data;
Ogive radius 1.5
Sectional density >.2610-.2630<
Form factor 1.10
Bal coeff 0.239-0.240
Herald
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RockyMTNClimber
Fuzzy numbers.... cowboy needs help.
2/27/2008 3:03:12 PM
This is a squad gun we are talking about? Shooting a 7mm dia. bullet (.284 inch) of appox. 131 gr. weight. Designed as a fire support arm to be fired off of a bipod, spindol, or even off hand sometimes? At what muzzle velicity will this be launched to maintain 2,000+ ft.lb.s of punch at 1,500 yards +/-?
My 7mm STW (a 8mm Rem. Mag. round necked down to accomodate a 7mm bullet) will drive a 140gr. Spitzer at a tad over 3400 fps.at the muzzle (1036 mps). This produces a whopping 1,819 ft.lb.s of energy at
500
yards. It makes a hell of an Antelope round I assure you!
What have I been missing? Where can I sign up to drive a 131 grain 7mm fmj out 1500 yards and have 10% more retained energy with a small arms cartridge? What round is this? I have a rifle action in my safe I could have worked up in this new uber magnum before hunting season.
Check Six
Rocky
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RockyMTNClimber
Rocky's coyote & antelope plinker
2/27/2008 5:21:13 PM
http://www.rifleshootermag.com/ammunition/RS7mmstw_071207I.jpg" width=420>
ht***tp://www.rifleshootermag.com/ammunition/7mmstw_071207/
It makes a dandy Elk rifle as well. The point is however this is about as high as 7mm performance gets (the Rem. Ultra Mag should get honorable mention also). After that you start seeing all kinds of problems with jacket seperation and you need to start using exotic materials for the projectile. This is not suitable as a automatic weapon because of the massive heat buildups when firing most of a hundred grains of propellent at a shot (need a slow cooker to build up that pressure, and a long barrel too).
7mm STW LOAD DATA
BULLET
POWDER
VELOCITY
DATA SOURCE
(Type)
(Grs.)
(Highest Velocity Loads Listed)
Hornady 100-gr. HP
RL-22
83.6
3,800
Hornady
Barnes 100-gr. XBT
RL-22
81.0
3,634
Barnes
Sierra 120-gr. SPT
V-N 160
78.0
3,600
Sierra
Barnes 130-gr. XBT
H4831
79.0
3,523
Barnes
Sierra 130-gr. MK
RL-22
80.0
3,600
Sierra
Barnes 140-gr. XFB
IMR-7828
80.0
3,473
Barnes
Nosler 140-gr. Part
RL-22
82.0
3,382
Lyman
Nosler 140-gr. B-Tip
RL-22
79.0
3,410
A-Square
Sierra 140-gr. SPT
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Herald12345
2/27/2008 5:42:42 PM
http://www.rifleshootermag.com/ammunition/RS7mmstw_071207I.jpg" height="197" width="420">
ht***tp://www.rifleshootermag.com/ammunition/7mmstw_071207/
It makes a dandy Elk rifle as well. The point is however this is about as high as 7mm performance gets (the Rem. Ultra Mag should get honorable mention also). After that you start seeing all kinds of problems with jacket seperation and you need to start using exotic materials for the projectile. This is not suitable as a automatic weapon because of the massive heat buildups when firing most of a hundred grains of propellent at a shot (need a slow cooker to build up that pressure, and a long barrel too).
7mm STW LOAD DATA
BULLET
POWDER
VELOCITY
DATA SOURCE
(Type)
(Grs.)
(Highest Velocity Loads Listed)
Hornady 100-gr. HP
RL-22
83.6
3,800
Hornady
Barnes 100-gr. XBT
RL-22
81.0
3,634
Barnes
Sierra 120-gr. SPT
V-N 160
78.0
3,600
Sierra
Barnes 130-gr. XBT
H4831
79.0
3,523
Barnes
Sierra 130-gr. MK
RL-22
80.0
3,600
Sierra
Barnes 140-gr. XFB
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