Cold War Fletchette Rifle Concepts

[Mosin Bubba]

I got reading about some of those 1950s Project Salvo guns, where they tried building those fletchette rifles, and some of those results sound almost too good to be true. This is from Wikipedia:

"Various multiple barrel rifles entered the project. The resulting "burst simulators" were tested in 1961, and the general conclusion was that the light weight of the flechette meant that it could be fired at extremely high rates of fire, the baseline being 2300 rpm, from a weapon of only 3.5 pounds (1.6 kilograms), fully loaded with 60 rounds. Accordingly, the Army became extremely interested in the weapon.[citation needed]"

"Further development continued by adapting a Winchester Model 70 rifle with new XM110 5.6×53 mm rounds firing a single dart. The result was a weapon with somewhat less accuracy than the 7.62×51mm NATO rounds, but with equal penetration and a trajectory so flat it could be fired with no sight adjustment out to 400 yards (370 m). Better yet the rounds were very light, and had almost no recoil in comparison to even the 0.22-inch caliber weapons under development."

Now the article does mention that fletchettes were expensive and difficult to make accurate. The latter part sounds like it's kind of inherent to the darts, but I don't know if the former part could be fixed with economy of scale.

Still - a 3 pound rifle with zero recoil and no drop out to 400 yards? Why didn't these wunder-guns make it into production?

Obligatory pictures of said space age wunder-guns

 

[hdwhit]

The Special Purpose Individual Weapon (SPIW) program which included investigation of small diameter projectiles (including the flechette) went on throughout the 1950s. Depending on what you want to identify as the descendant of the flechette, it could be argued that development of the technology is still going on.

I'm sure there are a lot of perspectives that people can offer depending on when they were involved with the project and what they were doing with it. What I do know that might be relevant is that both my grandfather (a senior Infantry officer) was part of a team that evluated the technology in the earlu 1950's (probably some time shortly after the end of the Korean War). Separately, my father (a senior officer in the Transportation Corps) was part of a team that evaluated the technology sometime in the 1960's.(probably 1964 based on where we were stationed at the time). In the 1970's when flechettes once again caught people's imagination, I was treated to their "war stores".

The Infantry contingent that my grandfather was part of were horrified by the abysmal accuracy out beyond 200 or 300 yards. The use of "stacked" projectiles seemed anathema to the entire idea of marksmanship and "Hits Count". And in spite of what the test data said, nobody believed such a small projectile could actually put a man down.

The Transportation Corps contingent was horrified at the rate of fire. At 2,000 rpm, 60 rounds lasts about 1.5 seconds. Just tap the trigger a couple of times and your magazine was dry. And how did anyone expect them to find the ships, trains and trucks to get that amount of ammunition across the ocean and distributed to the men?

I'm sure you'll get a lot of other perspectives, but these are just two from guys who were there at different times.

 

[CapnMac]

There were all sorts of issues with flechettes.
Low mass projectiles have all sorts of wobbly stats--you can accelerate a 1 gram ping pong ball to pver 100m/s, but keeping that little mass supersonic is problematic.

Next, the length to width on the flechette means they actually have to be made to significantly higher standards than ordinary ball ammo. The material also has to withstand some stout stresses--so, you wind up needing a material like tungsten for the darts.

Then, there's the whole spin or don't spin the projo argument to sort out. If you use fins, they have to be quite strong, and also huely precise. Spinning projos in the 2-3mm diameter range is complicated, too.

However, there's a much larger logistical issue. One which has doomed a number of promising ammunition designs. Which is GPMG ammo (and, to some extent, SAW ammo). For suppressive use, you need to engage targets--largely by suppression--at right at three times rifle range. If your fielded rifle is good to 300m, you need your GPMG able to engage at 900m. So, with flechettes, you are going to need separate MG ammo (and, really, separate SAW ammo). Two different ammo trains is complicated. This is what doomed the .276pedersen and the Brit .280 round--the ammo was quite good for infantry rifles, but not so much for MG use.

Lastly, best way to run flechettes is to sabot them and set them in bottlenecked cartridges. Ok, for a 2-2.5mm flechette, you need about a 5.5-6mm sabot just to make manufacturing sensible. So, you have just created a 5.5mm rifle with a bottleneck chamber. Which you could load with a 50-60gr ball and get known performance versus a 10-15gr dart that might or might not be a laser beam.