View Full Version : .357 sig with spitzer-bullet in a carbine/smg barrel.

March 20, 2005, 08:30 PM
Okay, I first posted this in the Full auto-forum, but didn't get any response. Seems the full-auto guys are more interested in gun-**** (Nothing wrong with that offcourse :rolleyes: ), the real world and legal issues, than this kind of stuff. So I repost my post here as this forum, in retrosight, seems far more suitable.

I have seen a move towards armor piercing rounds in SMG's recently(H&K MP7 PDW and FN P90, as well as the recent sweedish PDW), but I have also read a lot of articles by gunwriters questioning the stoppingpower of the 4.6mm HK round, and the 5.7mm FN round, because of low energy/low diameter(The FN p90-round has about as much energy from the P90 as a 9mm+p from a pistol. The H&K round even less).

The problem with the .223 compact carbines(I'm not neccesarly thinking of the M4, but the even shorter barreled supercompact XM-8, or HK G36C) is lack of velocity, and as a result the bullets don't fragment, and this hurts stoppingpower(ice-pick like performance). The problem with the 9mm, .40s&W and .45acp guns, is the lack of armor piercing abillity, and lack of effective range due to more rainbow-like trajectory and faster loss of velocity.

This got me thinking. What if you put a somewhat longer .355 diameter spitzer-bullet in .357 SIG brass, with a steel or tungsten tip, and a small circular cavity around the steel/tungsten tip, like a conventional hollowpoint just smaller, so that it would both penetrate soft body-armor, and expand if hitting an un-armored enemy. Also, in the longer barrel of an SMG, the high pressure of the .357 sig would result in a larger gain in velocity(as with the .357 magnum, which practically doubles it's energy from revolver to carbine because of the longer barrel), and thereby more energy than any conventional SMG, or even the fine-caliber HK(4.6mm) and FN(5.7mm) guns. Also, a longer spitzer-bullet might also result in better ballistics and better sectional density. At least, that's the theory.

So, what I'm wondering about is if this, in theory, would be plausible for use in either a slightly modified(rechambered and new magazine) conventional SMG like the H&K UMP, or in a (theoretical) SMG designed around this round, and with a Calico or PP-90M1-like helical magazine. A helical magazine would give the gun even more ammo per magazine than the FN P90. I am not thinking of this round for use in pistols, only in SMG's and PDW's.

So, give me input people. Inform me of anything I have overseen, anything that speaks against this solution, or anything you think could improve upon this. Also, if you think this is a good solution, I want to hear it too. :)

August 31, 2009, 08:56 PM
I'm bringing this back from the dead b/c I find the topic intresting. I am also curiuos about the .357 sig in a carbine application. Anyone care to discuss?

September 1, 2009, 07:54 AM
The premise is questionable for two reasons:
The small rounds don't need to fragment or expand, they work via large hydrodynamic shock. Have a look at temporary cavity in a soap block fired on with a small high velocity round, and tell me that's an ice pick wound.
The second, and we're discussing military rounds, is logistics; armies switch to lighter rounds not because they have better wound ballistics, but because it's easier to get a lot of them to the soldier. Don't forget, the military does NOT shoot to kill in conventional warfare. A dead enemy is good, but a wounded enemy needing 2 guys carrying him of the field, and 10 guys to put him back together over the next 6 months is better.
If you want to make a 357 sig people killer, go for a copper solid with tungsten core. You get both high velocity armor piercing and predictable expansion/fragmentation. Biggest issue is that you will exceed maximum length due to the spitzer bullet, so you need massive redesign of your gun. Maybe start with something like a rebarreled .30 carbine M1, those rounds arre half an inch longer than a 357, so you got plenty of room in the action to play with your new design.

September 1, 2009, 10:09 AM
There was something sort of similar to this offered a while ago in the form of the .224 BOZ, but I haven't seen any follow-up to it; the idea was, you could use AP or semi-AP 5.56 bullets when you desired additional penetration, or soft-point or FMJ bullets when you wanted more target effect, etc. You're really walking a pressure tightrope when you try to put heavy bullets into a pistol-sized case, since a hot day can turn a relatively safe load into an over-pressure situation.

James K
September 1, 2009, 01:06 PM
First, the idea that "military does NOT shoot to kill" is nonsense. If it were true, the army would issue rifles in .22 LR. And troops don't stop fighting to carry off the wounded, they leave that to the medics and keep on with the mission. (Only in movies does all the action stop and all the soldiers gather around the wounded soldier to hear his dying words and witness his dramatic passing.)

Second, the idea of combining an expanding bullet with a penetrating one is not new but dates back to the bronze tips used in hunting ammo decades ago.

Third, true "armor piercing" bullets (black tip GI ammo) does not penetrate from force but from heat, which melts or softens the armor so the core can penetrate. No pistol-type ammo has enough energy to do that.


September 1, 2009, 10:32 PM
Sorry to be a killjoy, but there is lots of bad info here.

The small rounds don't need to fragment or expand, they work via large hydrodynamic shock
The speed of sound in soft tissue is about 3620 fps. Very few rounds can produce this velocity. If a round impacts below this velocity, there is no hydrodynamic shockwave. Just like a plane traveling at Mach .7 produces no sonic boom.

Have a look at temporary cavity in a soap block fired on with a small high velocity round, and tell me that's an ice pick wound.
It's an ice pick wound.

Temporary wound cavity has been debunked several times over as a wounding mechanism. Living tissue is soft and springy. It stretches and then returns to it's original shape. Even the Liver, a rather rigid tissue, resists the affects of the temporary wound channel very well.

It is PERMANENT wound cavity that is important. A .308 FMJ bullet will make a nasty temporary cavity in soap, but have you ever wondered why FMJ ammo is explicitly banned for hunting anything larger than a coyote? A deer is not a block of soap. It is a living animal and tissue is not soap.

Don't forget, the military does NOT shoot to kill in conventional warfare.
Already dealt with. Look at Blackhawk down, how many soldiers were wounded, some seriously, that KEPT FIGHTING. A dead solider can't shoot back, a live one can.

Now, back to the OP.

The reason why there is no interest in a 357 sig AP load for SMGs is that 9mm AP is already readily available that will penetrate. Some of these 9mm projectiles have been loaded into .357 sig ammunition, though it is for use in handguns.

Information on 9mm AP ammunition is rather scarce as it's manufacture and sale is strictly controlled for obvious reasons so there is really no motivation to provide the public with information.

VBR-Belgium 9mm Armor Piercing bullets (http://www.youtube.com/watch?v=ZyKMz3tYx-M)

This is one of the best 9mm AP designs that I have been able to find information on. It will defeat any III-A or lower body armor.

Rumor mill time:

According to internet rumor, there are some loadings that can defeat some, but not all, Level III armor. The ceramic based hard plates seem to be the vulnerable types, as the first round fractures the plate, but generally does not penetrate. (Supposedly it is possible in very rare cases.) The second round to impact can penetrate the compromised ceramic plate, again, this is not guaranteed. I have no idea if any of the info in this paragraph is true or just rumor.

Most of these 9mm AP rounds will deliver superior terminal performance to the 5.7 rounds.