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357SIGFAN
08-02-2011, 05:37
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/ss174/amw4896/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 :boohoo

Curious:

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

godson
08-02-2011, 06:08
I believe that this round should suffice. Regarding to that of which your are to just gauge the velocity and performance of ballistics. :lifter 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
08-07-2011, 09:29
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 :rolleyes:

357SIGFAN
08-09-2011, 03:16
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
08-10-2011, 11:54
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
08-13-2011, 00:34
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.

Buffalobob
08-13-2011, 06:37
30gr is 30gr whether its solid copper or jacket lead.

Wrong!

An object will tend to achieve a minimum energy configuration. A partition achieves that through the deformation process as is shown in the picture. How your bullet does it I do not know but I doubt that it is consistent. The reason long VLD bullets require fast twist barrels is that flying point first is not a minimum energy configuration therefore energy must be added to prevent it from achieving such a configuration. The bottom line is what does one wish for the bullet to do once it has expanded.

I personally do not mind tumbling bullets because that is what we used and that makes a non-expanding bullet cause a larger wound channel (with less penetration). However one simply should know what a bullet is going to do before using it for serious work. Having been down the road with semi wet newspaper I don't do that anymore being as the result can be very misleading.

357SIGFAN
08-13-2011, 10:03
Doubletap

357SIGFAN
08-13-2011, 10:06
Wrong!

An object will tend to achieve a minimum energy configuration. A partition achieves that through the deformation process as is shown in the picture. How your bullet does it I do not know but I doubt that it is consistent. The reason long VLD bullets require fast twist barrels is that flying point first is not a minimum energy configuration therefore energy must be added to prevent it from achieving such a configuration. The bottom line is what does one wish for the bullet to do once it has expanded.

I personally do not mind tumbling bullets because that is what we used and that makes a non-expanding bullet cause a larger wound channel (with less penetration). However one simply should know what a bullet is going to do before using it for serious work. Having been down the road with semi wet newspaper I don't do that anymore being as the result can be very misleading.

Both in wet news-paper, water-jugs, and correctly calibrated gel, the MK318 MOD0 SOST ammunition will fragment very shortly after impact. The front half of the bullet will become a snow-storm of lead and copper, and the back half (solid copper) will continue forward with minimal radial expansion (more or less, depending either on flesh or wood or whatever it hits) like the solid copper wad-cutter it has become. Not enough people have yet been shot with it to say what it does to people, at least, enough people to get back to me.

The MK318 MOD 0 SOST is not dependent upon yaw to fragment. It performs reliably out to 100m from a 10.5" barrel. Its performance is much more predictable than M855, which it was designed to replace.

I do not understand what you are trying to say when you indicate to me that a 30gr copper projectile will penetrate a shallower distance than a 30gr copper-jacketed projectile (meaning, the base of the SOST vs. the base of a Nosler Partition.)

Their meplat diameter is assumed the same, and their weight is the same. Penetration should be identical.

However, your Nosler partition is a hunting bullet, so instead of fragmenting (one hopes...) it will expand. It is not like the SOST at all, in this regard, which is designed to rapidly fragment, shearing at the first band as I have pictured. Every single bullet I have recovered from every medium I have shot, as well as every picture of every single bullet recovered that I have seen, shears at this point. Looking at the cross-section I took of the bullet, this is easily explained.

The SOST does what it was meant to do: Rapidly fragment WITHOUT having to first yaw, and yet provide good penetration afterward, and against barriers such as glass, car-bodies, and the like.

If it helps, think of a Speer TNT 30gr Varmint bullet stacked on-top of a 30gr solid-copper wad-cutter. That is how the SOST performs, in the simplest of terms.

wolfganggross
09-25-2011, 08:53
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