Ballistic gelatin test results : 12 gauge Sabot Designs Flechette Sabot cartridge

[Brass Fetcher]

Cartridge : 12 gauge Sabot Designs Flechette Sabot (19 flechette cartridge)

Firearm : 12 gauge 3.5" magnum shotgun with 24" barrel length and cylinder choke

Block calibration : All depths corrected (Block was within calibration tolerance 7.8cm @ 575 ft/sec)

Single shot fired at 7 feet distance. Average impact velocity was 1931 ft/sec. Of the 19 flechettes that impacted the block - 3 experienced severe yawing and exited the sides of the block within 6" of penetration, 9 penetrated 15.8" of ballistic gelatin then 12" of polyester bullet arresting box (which in my experience is roughly equal to 16" of ballistic gelatin). These 9 flechettes traveled with sufficient velocity to utilize the stabilizing fins as wounding structures until an average 11.1" penetration depth. This cracking should be evident in the second photo below.

The remaining 7 flechettes exited the sides of the block sometime between 6" and 12.0" penetration depth.

 

[Gordon]

Looks like something that if you shot a dog with it at say 20', it more than likely would yelp and howl until you shot it with buck or a slug!

 

[GTSteve03]

9 penetrated 15.8" of ballistic gelatin then 12" of polyester bullet arresting box (which in my experience is roughly equal to 16" of ballistic gelatin). These 9 flechettes traveled with sufficient velocity to utilize the stabilizing fins as wounding structures until an average 11.1" penetration depth. This cracking should be evident in the second photo below.

Interesting, never would have thought flechettes would penetrate so deeply. However, it seems way too much penetration for home defense use, and what else would you really use these for? Do they have any accuracy at all past a few yards?

 

[highorder]

Interesting, never would have thought flechettes would penetrate so deeply.

that's their only purpose.

 

[GTSteve03]

that's their only purpose.

True, but I was assuming such small flechettes being kicked out of a shotgun weren't going to fly very true and actually hit at the right angle to penetrate.

Also, while ballistic gelatin simulates soft tissue well enough, I'm sure these will be easily deflected by any bones, and I wonder how heavy clothing affects them?

 

[highorder]

you make a good point about the shotgun. I wonder what percentage usually flies true, and what type of wad/load makes for the best pattern...

 

[Brass Fetcher]

Attached are two photos of targets that I shot once each, one at 10 feet and the other at 21 feet, to get an idea of the spread (and where I should aim at the gelatin block most importantly!).

I think that the flechettes (as tested) have a good potential for hard armor penetration. Bone yields at 16000 psi... a flechette traveling at 2000 ft/sec (as in this case) provides a 'stagnation pressure' of 26900 psi. So, at that speed, it will go through bone without slowing down much.

When I look at the spread at ten feet, two things jump out - the first is that the gelatin block may have been missed by some of the flechettes from the shot taken at 7 feet. The other is that, if the extreme yaw/pitch angles depicted in the 10ft. shot and less so in the 21ft. shot were indicative of what happened during the shot that was fired at the gelatin, many of the darts that hit the block hit sideways. Due to the more resistive nature of the gelatin, the darts were 'forced' to right themselves and travel in a point-forward fashion.

Those darts that were yawing too much, likely were bent by the pressure exerted by the gelatin and quickly curved off of the line of action and out of the side of the block.

 

[the naked prophet]

Keep in mind that half the darts are loaded backwards in the shell. It takes several feet for the darts to straighten out and fly, well, like a dart. If you were to pattern them at, say 15 yards, I'll bet they would just about all hit straight on, and the pattern wouldn't open up any more from that point on.

 

[Shadowangel]

I'd think these would be an excellent counter to soft body armor. Very good penetration on target, without the extreme penetration of a slug.

 

[Zoogster]

Great test.

I had not thought about lots of yawing. A flechete designed for yaw by having a weak point mid shaft designed to bend might dramaticly increase thier potential tissue damage.

Also flechettes are designed for hard target penetration, flesh penetration is entirely different. Thin hard barriers are penetrated more by the shape, and hardness of the projectile while the distance traveled in the target or tissue has a lot to due with mass and drag.

Both contribute to penetration overall, but one has more impact in an area than the other.

This is because in tissue the round has force exerted not just by what is in front of it, but along the sides as things flow around it. However in penetrating a hard barrier most of the effort is in forward penetration of a thin object and once that is achieved less significant resistance on the sides.
This means a steel flechette has better penetration against hard thin objects than it does in tissue.

I can actualy see some potential for modified flechettes intentionaly designed to yaw after several inches of penetration. Along the lines of the PDW ammunition designed to make up for its lack of tissue damage through yaw and tumbling after soft armor penetration.

Without reliable yaw flechettes still do far too little tissue damage.

A test that would be nice is one with flechettes penetrating some barrier prior to tissue.
Maybe file a little cut in the metal on the shaft toward the rear of each flechette (a little less than half way through, and you could fill it with soft solder to keep the same profile if desired), just enough to create a path of least resistance and encourage bending and subsequent yaw and tumbling after penetration rather than just slightly deviation. Then rather than exiting the sides or flying straight they should tumble end over end similar to how the military FN 5.7 ammunition is designed to perform.

 

[Matt304]

I think a big problem with the design is due to the way in which they are assembled. That 10 foot target gives a very good idea as to what is happening. The backwards flechettes are still trying to become aerodynamically stable. Because half are unstable when they fire, their first part of flight is very erratic until they do become stable. I have reason to believe that this will cause them to finally stabilize headed off course. They just can't retain all of the forward inertia, the air will deflect them some. Also, some of the backwards flechettes may actually disrupt the stable ones they are next to when they leave the barrel, further disrupting flight patterns. All in all, it's a very ineffective design if you ask me. You have something which may penetrate armor at 25 feet, but not at 10 feet or less. And at 25 feet, only half may even potentially strike. What good is that?

I think these could be designed a bit more effectively. As in, all are stable from the git go.

I can envision the design in my head which may work. You have a sabot holding the darts. All of the darts are facing forward. Half of the darts sit on the sabot bottom, the other half are spaced the height of the fins off the bottom. This allows them to fit without fins getting in the way, and all facing forward. Now the sabot is filled with shot filler, and the design is locked up tight when it is loaded, so all the flechettes are gripped in position firmly. When the sabot opens, I think the flight characteristic would be many times better than the original design.

 

[RyanM]

Problem is, flechettes are crap at wounding, even with the fins. Puncturing armor is no good if it doesn't do much on the other side. I imagine a 12 gauge slug, even if it doesn't actually penetrate soft armor, would still put someone in a world of hurt, and probably be more reliable at incapacitating.

 

[4thPointOfContact]

I know; it's like kicking a dead horse to resurrect this but - - there has recently been some activity on Georgia Packing with regards to flechette rounds.

The experience matches everyone elses, flechette's are not the choice for serious shotgunnery.

 

[kBob]

The Veitnam era 12 gauge Flechette rounds were made to give shot gun armed troops a weapon in hand that could reach out to targets at the ranges 00 Buck would be purely hit or miss.

Having a 1.5 mm diameter nail fly through you at 125 meters would be much worse than 8 or 9 .33 caliber Buck shot missing you entirely.

The Army was flechette happy at the time. The 105 howitzer had a very effective "behive" round that used flechetts of about this size and even the 90mm Recoiless had a round using this sized flechette.

Such a round was also develped for the 155mm gun system.

The 2.75 inch Folding fin free flight rocket used on helo gunships had a flechette round that used longer flechettes of about the same diameter and they were well thought of.

The rockets and artillery rounds used a time fuze to despense the flechettes as they approached the target.

THe Recoiless rifle used basically a big honking shotgun round. The slow twist of the gun did tend to cause more spread, but not as much as one might think. Supposedly the patern remained thick enough to practacally gaurantee a hit on a kneeling man with in ten meters of the point of aim at 300 meters.

In the 12 gauge flechette rounds would work much like anything else in a shotgun inside 10 meters, and hold tighter patterns with the vast majority of the flechettes than other shot loads to 125 meters.

The rounds may be a bit hard to explain to a grand jury or a trial jury by a home owner with a bloody hallway and close up against un armored targets buck does work just as well.

The flechettes were made by a nail making firm. I visited a plant that made nails and wire mesh for indsustrial use once (looking for a job)and there were drums of finished flechettes stacked along the side of the loading dock. The drum that was open and three quarters full was interesting.

When I was an Artillery Officer in the early 1980's my boss would occassionally wear a ditty hat in the field that included a pair of flechettes stuck through band of the hat. I later noticed other artillery VN vets doing the same. Think knotches in a gunfighter's pistol grips. A most intersting use of the flechette.

-Bob Hollingsworth