MK318 Mod 0 SOST Terminal Performance

[357SIGFAN]

So far, there has been very little information released regarding the ammunition that I can find. From what I have been able to gather:

-III Soft body-armor does nothing to stop or slow it.
-It is not yaw-dependant.
-The front portion of the projectile from the top-band up fragments, and the copper "shank" continues to penetrate.
-The "neck" of the wound-tract is extremely short, reminiscent of Hornady T2 or MK262.
-Accuracy is equal or better than M855.
-Actual tested velocity is roughly 2900fps from a 14.5" carbine.

Here is a picture of a block of gel:

http://i573.photobucket.com/albums/s...6/DSCF4393.jpg

If anyone has any more information regarding this ammo, I am curious to hear it. Just ordered a case. Please be gentle if you think it sucks. I have an emotional investment now

Curious:

-Minimum terminal velocity for reliable fragmentation?
-Performance comparison to M855 on homogeneous hard-targets at distance?
-Field use impressions?

[godson]

I believe that this round should suffice. Regarding to that of which your are to just gauge the velocity and performance of ballistics. We try things we change things. We get insight and we try those things no one should negatively comment on what your trying to achieve.

[357SIGFAN]

My SOST ammunition has arrived. I am going to shoot it into a water-logged phone book and compare it to a round of M855. Yay for scientific method

[357SIGFAN]

My ammo finally arrived. The testing consisted of wet phone books and water in foam icechests. Whether book or water, the front half of the sost disintegrated at 50 yards from a 16" ar. It performed just like a nosler ballistic tip while the rear was like a solid copper wadcutter from the first "band" back.http://i54.tinypic.com/2rfrmtk.jpg It was not at all yaw dependent and fragmented nearly immediately. I do not know if the front crushed and shattered, or violently over expanded. It left a lead and copper snowstorm in whatever it hit while the copper rear punched onward. It went through about 10" of soaked book and 20" of water. The fragmentation was in the first 1-6" of books. M855 I tested left a bigger hole in the soggy books, but was 100% yaw dependent. Consider the front 1/2 to be equal to a slightly sturdier speer TNT projectile and the back half a solid copper slug with a flat meplat. A real "do it all" round that frags violently and still easily penetrates 14"+.

http://i54.tinypic.com/287jbqp.jpg
(ignore the bit of jaggedness near the front band, it is where I gripped the round with pliers to cross-section it.

Compared to a .277cal 90gr Speer TNT round (sourced from the internet).
http://i56.tinypic.com/2zrgoqt.jpg
The SOST does not appear to be fluted like the TNT, but I have no way of measuring the "hardness" of its core, the ductility of the jacket, etc. All I know is that it performs IDENTICAL to a Winchester BST when fired into foam ice-chests full of water. The first ice-chest (about 10" deep) has a flurry of sand-sized lead and copper, but unlike the BST, the SOST round's "shank" continues through the first, second, and third ice-chests, and fell to the ground after bouncing off the exterior of the fourth. It also penetrated 2 ice-chests and about 10" of waterlogged (only soaked for 20 minutes) phonebooks. That little rear-half has some serious penetration, and the front half just seems to disintegrate.

[Buffalobob]

You might want to consider that lead is a lot denser than copper and that momentum is the product of mass and velocity.


This then leads to the interesting possibility that a Nosler partition that has expanded down to the partition is heavier than a piece of solid copper and will penetrate further. Of course there is the energy of deformation loss and then there is the question of frontal area of a Nosler so it might not work out so simply.

[357SIGFAN]

Originally Posted by Buffalobob

You might want to consider that lead is a lot denser than copper and that momentum is the product of mass and velocity.


This then leads to the interesting possibility that a Nosler partition that has expanded down to the partition is heavier than a piece of solid copper and will penetrate further. Of course there is the energy of deformation loss and then there is the question of frontal area of a Nosler so it might not work out so simply.

The SOST ammunition is made to fragment for the first half. Partitions are meant to mushroom.30gr is 30gr whether its solid copper or jacket lead. The base of each weigh about the same, the sost round is just larger. I like fragmentation more than expansion regarding terminal performance.