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Posted: 11/6/2003 1:15:39 PM EDT
[#1]
Don't know the answer to your question, but welcome to the forum! Don't know if you've been browsing the site for long, but there's lots of good info here. Have fun!
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Posted: 11/6/2003 2:10:37 PM EDT
[#2]
Welcome to the forum!
Straight off the label of my 8 pounds of WCC-844: 5.56mm M855 62 grain Green Tip - 26.1 gr. Out of Military Manual available online for the M193: 5.56mm Ball M193 WCC-844 - 28.5 gr. Now, these loads must be reduced and worked up to. *Normally* powder mfgs. recommend 10%. Let your concience be your guide. I use 27.5 grains of WCC-844 with the Win. 55 gr. FMJ bullet. Posted for informational purposes only! Danny |
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Posted: 11/6/2003 2:12:43 PM EDT
[#3]
The US Military specification for M193 calls for either 28.5gr of WC-844, or 26.5gr CMR-170. M855 ammunition is supposed to have 26.1gr WC-844. Quality control tolerances allow for a slight variance above or below the stated powder charge, but I can't seem to find the numbers at the moment as to how much variance is allowed before it is considered to be out of spec.
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Posted: 11/6/2003 2:27:36 PM EDT
[#4]
Military powder DOES have variation in it that can be much larger that would "be allowed" in commercial cannister powder. When you go buy a can of WW748, you can use the same load as the last can, because the powder is very consistant. Not true with military powder, so each new lot must have the load worked up for it.
Thus, no measurement you see is going to be totally accurate, because the load will change depending on powder lot. However, given that both M193 and M855 can be loaded with the same powder, it will generally be true that the lighter bullet will use slightly more powder, and will have a higher muzzle velocity. -Troy |
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Posted: 11/6/2003 3:13:54 PM EDT
[#5]
Neither M193 nor M855 Ball is loaded to a spec for powder weight, nor is any US military ammunition.
They're all loaded to a [b]velocity standard[/b]. The Army Ammunition Sheets list the [i]nominal[/i] powder charge needed to achieve the velocity spec; the ammunition is [i]test fired[/i] several times during production to ensure it meets this spec. Actual powder charge is varied to maintain velocity standard. -- Chuck |
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Posted: 11/6/2003 4:03:33 PM EDT
[#6]
hi all ' and 10x 4 the warm greetings.
also i would like to thank u for the help... another question - if the M855 velocity is higher , how come there seems to be less propellant , let alone that the bullet is heavier and the pressure in the barrel is higher. p.s - excuse me for any typing error , i'm from israel. |
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Posted: 11/6/2003 6:35:01 PM EDT
[#7]
M855 velocity (62gr and ~3120fps [i]at the muzzle[/i]) is lower than M193 (55gr ~3265fps). There's more room in the case for more powder with the shorter M193 bullet and the projectile is lighter.
Note the milspec calls for velocity measurement of 3025fps @ 78' and 3250 @ 15' respectively, so it's hard to make direct comparisons of the [i]muzzle velocity[/i] without some ballistics software. -- Chuck |
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Posted: 11/7/2003 1:51:04 AM EDT
[#8]
indeed , now that i have checked , the muzzle
velocity of the m855 is lower. but according to what i know after about 200 yards the M855 starts to preform better then the M193 , is it due to bigger leak of speed of the M193? |
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Posted: 11/7/2003 3:30:15 AM EDT
[#9]
At 200 and 300 meters M193 Ball is still faster than M855. [From the M4 Carbine.] [s]I'm not sure what data your're reading which indicates otherwise.[/s]
Reliable fragmentation range of M193 is longer than M855 as fragmentation potential is linked to velocity. The window opens about 2500 fps. -- Chuck Edited for too many years shooting the M4! [;)] |
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Posted: 11/7/2003 8:38:26 AM EDT
[#10]
its written in the ammo oracle FAQ
http://www.ammo-oracle.com/#m855vm193 that the crossover point of the M855 speed over M193 is at 200 yards. |
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Posted: 11/7/2003 3:11:07 PM EDT
[#11]
I typed too fast:
You're right on the 20" 2500fps crossovers with 20" bbls. The 2700fps window in the M4 Carbine closes at 100 yards with M193 and at 75 with M855 Ball. They both run out of the 2500fps window right aroung 150 yards. -- Chuck |
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Posted: 11/7/2003 9:58:44 PM EDT
[#12]
Quoted: M855 velocity (62gr and ~3120fps [i]at the muzzle[/i]) is lower than M193 (55gr ~3265fps). There's more room in the case for more powder with the shorter M193 bullet and the projectile is lighter. Note the milspec calls for velocity measurement of 3025fps @ 78' and 3250 @ 15' respectively, so it's hard to make direct comparisons of the [i]muzzle velocity[/i] without some ballistics software. -- Chuck The reason for the difference in powder quantity between the two is not directly related to the volume in the case due to bullet seating depth. Everything revolves around pressure. I don't remember the exact number right now, but the pressure limit for .223 is over 50,000 psi. (It may be more for 5.56.) They drive both kinds of ammo as fast as they can without breaking that pressure limit. That is what the amount of powder is based on. The reason the lighter bullet gets more powder is because it will accelerate quicker down the barrel and pressure won't build as much. |
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