50 BMG Multi Ball?

Picked up what is reported to be a 5-projectile encased in plastic 12.7x99mm cartridge. There’s some sort of pin sticking out the tip and what appears to be two projectiles inside the plastic. Is this legit? Any guess on value?

These are legit. I’ve seen a guy at the local gun show with a bunch in the past. My understanding is that they are from the Vietnam era, and cartridges for the SALVO Squeezebore.
Other IAA members can no doubt add some useful info

Legit, very common.

Salvo Squeezebore design had two sources, the original RICA and later Colt, as Colt bought the design and hired the developer to work for them.

Many variations of the SSB design, no one seems to know just how many, but 4 designs are very common, $5 level, with two that are very difficult to find, $25-$50 level, another design that’s in the $100-$150 range, and even a tracer variant (which, unfortunately, isn’t marked in any fashion, so you can’t tell it from the “ball” variant without an Xray).

For the .50 cal, it’s 5 cones per cartridge, but the concept exists in 30-06, .308/7.62 Nato, .45 ACP, .38 Spcl and 9mm. Those are 3 cones per cartridge.

Design is intended to provide multiple projectiles onto target, but with a taper bore application, .50 at the chamber, .30 at the muzzle for instance to create dispersion. Some tests during the VN war, Riverine Warfare boats using the design as a counter-ambush defense weapon, really mows down vegetation in the jungle river bank.

Check the archives here, been discussed several times, photos of the variants posted, even a cross-section photo.

Gunbroker has many variants for sale most all the time, various .50 designs and various calibers.

Lots of things to read after searching more appropriately.Thanks for the insight!

My 2¢:

Here some more pictures…

So there are no external clues to determine of an example is ball or tracer?

Jon as far as I understand no external markings. As some of you most likely know these were all loaded on WW II vintage brass, so the headstamp is not very important in some respects.
The two photos are bullet bases showing wall-thickness (the O.D. is the same in all three just the photo that makes one look smaller) & the other of the bullets with what I was told was the tracer ‘chamber’ for these on the right.

edited to add; The tinned style bullets Manuel shows but with a magnetic bullet is thought to be the 1st type