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. 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"+.
(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).
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.
Thanks. To me, it seems like it performs like a cross between the TBBC and a 40gr Nosler BT. Basically, as close to “do-it-all” as it gets.
I have 500 rounds of the stuff and am glad I bought.
Earlier you indicated that it did well out to 100m from a 10.5" barrel. That equates to about 2350fps. Am I to take this to mean that the front half fragments violently enough to sheer off as I pictured, down to @2350fps?
I’ve been looking around for a good general purpose duty load that I can buy in bulk. I’ve been debating getting this load as I’ve been seeing it more and more on the commercial market.
I 2nd his findings as that is exactly what the ones I shot did. The Mk319 did infact look like a traditional hunting bullet when fired into water from a 13" SCAR. The Mk318 I shot did identical to his from a 10" barrel. When time allows, I plan to play with this stuff some more through a test sheetrock wall, glass, & metal.
I think it’s a good round, the only thing that bothers me is the fliers with these rounds. I have shot this stuff from a SCAR & AR with similar results, 7-8 nice & tight, then 2-3 fliers. The Mk319 did the exact same thing from my SCAR 17 & a Remington M700 Vss. Now I did shoot 10 rounds of Mk319 through a KAC SR25 EM & for whatever reason (5R rifling), it grouped markedly better. There were no fliers. This puzzled me, & I want to get some more Mk319 to see what’s up.
The 318 I have is the brown box stuff from Palmetto State Armory. It came in a sealed LC can. The 319 is the white box stuff, again from Palmetto State
Get some windshields from your local junkyard to set up in front of your impact material, and hit it again, if you’re of a mind to. The barrier performance on that little beauty is definitely something to see.
Im general, larger groups are more likely to “fill” out the beaten zone of a given gun/ammo combo, so doing 10s/20s are more likely to give a more complete picture of what you’re dealing with. Those fliers could simply be at or near the outer edge of what that lot is capable of printing in that gun.
Also bear in mind that what you’re buying is what failed to pass some spec or another, and was made available for commercial purchase; that adds some intangibles that may or may not be seen in the stuff that does pass all tests and gets accepted by the contract holder, and may or may not be something one can analyze from what’s printed on target. That’s kinda boilerplate, and maybe I’m being pedantic typing that out…
Impossible to say what that might be unless somebody at the plant is willing/able to tell you why XX lot# was sold to Palmetto instead of going to the original customer.
I have yet been able to ascertain whether this sentiment is factually correct or simply an internet rumor. This is not the first time I have seen it. Does anyone have official confirmation from Federal which they can cite or link or post which confirms this? I.e., does anyone have proof of the above statement? The burden of proof is on the party making the assertion and I’ve seen no proof.
When we pay nearly a dollar a round, whether it is a “first” or a “reject” might possibly be important, depending, of course, on why something is rejected. The color of the box may be unimportant, although I have noticed that what is printed on the box does differ whether it is white or brown.
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"+.
