5.56mm MK318 mod 0

[General Lee]

Originally Posted by Irenaeus

Just since I recently finished Scahill's book: The ammo in question is RBCD's Armor Piercing Limited Penetration rounds, distributed by Le Mas.

Thank you. I couldn`t find my book to check it out.

Originally Posted by Sam Cade

Oh my.

Its pretty much all B.S. I mean, like CRAZY B.S.

I already suspect that.

[General Lee]

I came up with a funny thing. Mk262 Mod 0/1 is a 5.56x45mm 77-grain Open-Tipped Match/Hollow-Point Boat-Tail cartridge. A Sierra Matchking bullet.

So, it is HP-BB round? Or a Solid-BB? Or, simply its Solid non-BB?

I know that it is Match-grade, as in p.77 (Tactical Shooting ).

And, what is the difference between this round (Mk262) and Mk318?

[General Lee]

I read that Mk318 also is not yaw dependant.

http://www.dtic.mil/ndia/2009infantr...ioniii8524.pdf

What this means? Sam Cade seemingly make an answear below, but what else. This means that actually Mk318 Mod 0 is HP in GURPS parlance? Real world and legal issues apart.

Originally Posted by Sam Cade

With no yaw, you depend on fragmentation to wound.

[DouglasCole]

Originally Posted by General Lee

I read that Mk318 also is not yaw dependant.

http://www.dtic.mil/ndia/2009infantr...ioniii8524.pdf

What this means? Sam Cade seemingly make an answear below, but what else. This means that actually Mk318 Mod 0 is HP in GURPS parlance? Real world and legal issues apart.

A .22 caliber round (like the 5.56x45mm) that doesn't yaw will tend to have a pi- wound modifier in GURPS. The reason that the high velocity rifle rounds get a step up on the wounding modifier . . . IIRC, the dividing line for pi- for pistol rounds is about 8mm . . . is a combination of yaw and energy, due to compound effects from the temporary wound cavity and fragmentation.

So the .223 gets the pi instead of pi-, the .308 same way (though the .308 is more of an edge case for pi --> pi+ without actually getting there).

For the Mk318 mod 0, not being yaw dependent, based on the PPT, probably means you get enhanced wounding due to the separation of jacket, steel penetrator, and solid copper ballast material behind the penetrator. By splitting into three pieces even on normal impact, you get the same kind of outsized wound multiplier that the standard .223 gets on the account of bullet tumble and yaw in flesh.

[DouglasCole]

Originally Posted by General Lee

This means that actually Mk318 Mod 0 is HP in GURPS parlance? Real world and legal issues apart.

This is a bit odd. Consider a rifle bullet in 6mm caliber and with a 4:1 aspect ratio. The frontal cross section will be about 28mm^2. The sideways cross section will be 6mm x 6mm x 4 = 144 mm^2.

Most successful hollow/soft point (expanding) bullets in rifle designs manage to munch down to about double the diameter of the impacting round, increasing frontal area by 4 . . . about 112 mm^2.

If the yawing bullet also fragments, then, well, it gets even worse.

So why do snipers and hunters use hollow point, when clearly the solid fragmenting bullet is more devastating?

Well, hollow points tend to mushroom very quickly on impact, and when they do, the wound profile is quite reliable. Yaw is a somewhat random phenomenon, and happens differently in every wound. sometimes you get tumble right away, sometimes you don't ever tumble. Sometimes fragmenting destroys a perfectly good meal, or spreads internal nasty viscera into your meat.

Hollow points are predictable and reliable in how they work. Relying on bullet yaw depends on a lot of things that the shooter can't control.

In terms of wounding, then, hollow point probably doesn't add much in reality over yaw in terms of average effects. But yaw and fragmentation isn't reliable.

If you want to be fiddly, for small caliber high velocity rounds (less than, say 8mm), use a wound channel modifier of 0.5+ (1d6-1)/5. Hollow point always gets the step up from pi- to pi.

[ronom]

I believe Douglas Cole is right on that. The M855A1 is a steel penetrator,copper wire alloy core and copper jacket that yaws after penetration. this is generally implied in the request that procurement puts out.

[Anthony]

Originally Posted by Irenaeus

I have no idea to what degree the above information is exagerrated (if at all).

It seems to impute magical 'detect living flesh' properties to inert bullets.

Originally Posted by DouglasCole

In terms of wounding, then, hollow point probably doesn't add much in reality over yaw in terms of average effects. But yaw and fragmentation isn't reliable.

And doesn't happen much at all for lower velocities, including longer range hits with rifle rounds.

[DouglasCole]

Originally Posted by Anthony

And doesn't happen much at all for lower velocities, including longer range hits with rifle rounds.

Yaw will always be "attempted" in flesh for spitzer/ogive bullets, assuming exit doesn't occur first. The first thing that goes for smaller rounds is the fragmentation, though the bullet will often break in two at the cannelure if it has one. Then, at still lower velocities, that stops happening too, and you're only left with the yaw effect. The most common occurence of apparent failure to yaw is when the initial tipping of the bullet just changes the bullet's course, resulting in no effective yaw, but a really funky wound. The bullet tries to yaw, but can't/doesn't cut through flesh sideways like what happens at higher velocities.

From highest to lowest V, then:

yaw and fragment into many bitty bits
yaw and fragment into a few pieces, often two at the ridge used to seal the case to the bullet (cannelure)
yaw and eventually assume base-first orientation, no fragmentation
yaw, but change course and continue point forward in some oddball pattern
Doesn't even yaw

Hollow points/soft points more or less go like this:

Hit, expand and punch through the wound. Maybe the base of the bullet breaks off as a secondary fragment, but usually not.

Hit, fail to expand, and maybe continue in oddball pattern. Usually just hit fail to flatten and go right through.

Obviously, manufacturers spend (successfully) a lot of effort to make the expansion happen reliably. Plastic points, exposed lead, and hollow points all designed to do the trick.

[Sam Cade]

Originally Posted by Anthony

It seems to impute magical 'detect living flesh' properties to inert bullets.

....still less breathless than "eXtreme shock" add copy.


http://www.extremeshockusa.com/

E-Shock rounds are engineered to expend maximum energy into soft targets, turning the density mass into an expanding rotational cone of NyTrilium matrix particles, causing neurological collapse to the central nervous system.

Gotta watch out for the "density mass" LOL!

[General Lee]

Originally Posted by DouglasCole

A .22 caliber round (like the 5.56x45mm) that doesn't yaw will tend to have a pi- wound modifier in GURPS.

The reason that the high velocity rifle rounds get a step up on the wounding modifier . . . IIRC, the dividing line for pi- for pistol rounds is about 8mm . . . is a combination of yaw and energy, due to compound effects from the temporary wound cavity and fragmentation.

So the .223 gets the pi instead of pi-, the .308 same way (though the .308 is more of an edge case for pi --> pi+ without actually getting there).

For the Mk318 mod 0, not being yaw dependent, based on the PPT, probably means you get enhanced wounding due to the separation of jacket, steel penetrator, and solid copper ballast material behind the penetrator. By splitting into three pieces even on normal impact, you get the same kind of outsized wound multiplier that the standard .223 gets on the account of bullet tumble and yaw in flesh.

So one compesates the other. Still, Mk318 not being yaw dependant, have more chances to achieve results. That argument that corroborates my feeling that Mk318 is BB ( the PPT say Barrier, also), because you withdraw randomness, exchanging 2d for +7. Don`t know if it is Match, because IRC this bullect was projected to be used in CQB, not for precision shots. But, I don`t have authority to rule that, only guess.

Originally Posted by DouglasCole

So why do snipers and hunters use hollow point, when clearly the solid fragmenting bullet is more devastating?

Well, hollow points tend to mushroom very quickly on impact, and when they do, the wound profile is quite reliable. Yaw is a somewhat random phenomenon, and happens differently in every wound. sometimes you get tumble right away, sometimes you don't ever tumble. Sometimes fragmenting destroys a perfectly good meal, or spreads internal nasty viscera into your meat.

Hollow points are predictable and reliable in how they work. Relying on bullet yaw depends on a lot of things that the shooter can't control.

In terms of wounding, then, hollow point probably doesn't add much in reality over yaw in terms of average effects. But yaw and fragmentation isn't reliable.

If you want to be fiddly, for small caliber high velocity rounds (less than, say 8mm), use a wound channel modifier of 0.5+ (1d6-1)/5. Hollow point always gets the step up from pi- to pi.

Hollow Point have drawbacks, like (0.5) armor divisor. With this in mind, and with the benefit of hindsight, I don`t think that Mk318 Mod 0/1 is Hollow Point (in Gurps), either.

But, I think that somehow it have more capability to wound. Maybe not a full fledged Pi --> Pi+ (1.5), but a 1.25 wound modifier, round down. I`m still thinking.

It also would apply for M885A1, that have AP behavior combined with HP properties, accordingly with the respective PPT. I would stick with the solid with more "punch".

Sort of OFF-TOPIC: Douglas, you could tell me what you (TS playtesters, editors) have in mind with government issued HP-BB rounds for RRA LAR-15 and M-16 rifles in p.79 (Tactical Shooting)?