Let’s play the “What is it?” game!

[GAgunLAWbooklet]

My guess:

An early 20th century military tracer cartridge,
but not for a rifle or light machinegun, but rather a heavy MG like a .50 BMG or 12.7 mm,
or even a 20mm cannon.

I have nothing to use as a size reference, but the fact that it's got a blank pistol-sized blank round INSIDE the larger case makes me think it's .50 cal or maybe 20mm x about 110 mm in size.

The bullet / projectile is extra heavy, if the core is made of lead.

Having an extra heavy projectile would explain why the propellant charge is contained in a sub-caliber blank cartridge; every heavy bullets need much smaller powder charges to avoid exceeding limits on chamber pressure. Yet if they put a small amount of gunpowder in that big fat 20mm cannon case, it would either be dangerous or have unreliable ignition, since the powder charge wouldn't necessarily be sitting atop the percussion primer.

The bullet / projectile seems to be a tracer type. It looks like it has a lot of tracer compound for a long burn time.
The bullet's large size, its blunt, round nose, and presumably heavy weight makes me think it was meant to be a slow round that needed a long-duration trace to make it to the target while burning.

SO, what was it used for?
MY GUESS: To be fired at Zepplins / airships / barrage balloons that would be filled with hydrogen.
The slow velocity of the bullet would increase the chances of the tracing compound catching the interior of the airship on fire.

 

[cmshoot]

View attachment 3702228

My guess:

An early 20th century military tracer cartridge,
but not for a rifle or light machinegun, but rather a heavy MG like a .50 BMG or 12.7 mm,
or even a 20mm cannon.

I have nothing to use as a size reference, but the fact that it's got a blank pistol-sized blank round INSIDE the larger case makes me think it's .50 cal or maybe 20mm x about 110 mm in size.

The bullet / projectile is extra heavy, if the core is made of lead.

Having an extra heavy projectile would explain why the propellant charge is contained in a sub-caliber blank cartridge; every heavy bullets need much smaller powder charges to avoid exceeding limits on chamber pressure. Yet if they put a small amount of gunpowder in that big fat 20mm cannon case, it would either be dangerous or have unreliable ignition, since the powder charge wouldn't necessarily be sitting atop the percussion primer.

The bullet / projectile seems to be a tracer type. It looks like it has a lot of tracer compound for a long burn time.
The bullet's large size, its blunt, round nose, and presumably heavy weight makes me think it was meant to be a slow round that needed a long-duration trace to make it to the target while burning.

SO, what was it used for?
MY GUESS: To be fired at Zepplins / airships / barrage balloons that would be filled with hydrogen.
The slow velocity of the bullet would increase the chances of the tracing compound catching the interior of the airship on fire.

That’s good hypothesis.

The round is modern, we used them when I was on active duty, and in the reserves. Developed overseas, for a weapon system we used in the Corps.

 

[EMC45]

.50 Caliber "spotter/tracer" round?

 

[cmshoot]

.50 Caliber "spotter/tracer" round?

You’re on the right track…….

 

[EMC45]

For the howitzer?

 

[cmshoot]

For the howitzer?

A lot smaller. Fired by a single Marine.

 

[EMC45]

AT4

 

[cmshoot]

AT4

Getting warmer.

 

[GAgunLAWbooklet]

Mk 217 spotter cartridge, 9 mm, which is used to confirm the ballistic trajectory and range to target on an anti-armor rocket launcher called the SMAW.

Or, it can be just used for training, letting soldiers (err, I mean MARINES) pop these giant tracer bullets into silhouette targets representing vehicles without letting the soldiers actually shoot real, and very expen$ive, anti-armor rockets!

 

[cmshoot]

Mk 217 spotter cartridge, 9 mm, which is used to confirm the ballistic trajectory and range to target on an anti-armor rocket launcher called the SMAW.

Or, it can be just used for training, letting soldiers (err, I mean MARINES) pop these giant tracer bullets into silhouette targets representing vehicles without letting the soldiers actually shoot real, and very expen$ive, anti-armor rockets!

View attachment 3704545View attachment 3704546

Yep. Basically, a 7.62x51mm casing, necked up to hold a 9mm bullet with an encapsulated tracer. The propellant is provided by a .22 Hornet blank shoved up the backend. This mimics the trajectory of the rocket itself. Not sure how someone came up with the particular combination of parts.

9 x 51mm SMAW (Shoulder Launched Multipurpose Assault Weapon)
Specimen and photos courtesy of Paul Smith

This is the training/spotting cartridge used with the 83 mm SMAW rocket launcher deployed by the U. S. Marine Corps beginning in 1984. The rocket launcher is based on the Israeli B-300 system. A British designed 9mm spotting rifle is mounted on the right side of the launcher.
The rocket launcher is reusable and each rocket comes in a disposable sealed tube which is affixed to the launcher. There are different 83mm high explosive rockets which include anti-armor (HEAA) and a dual purpose anti-fortification (HEDP) rounds.
The 9mm rifle is used for for spotting to increase the first round hit probability with the rocket round, and for use in training. The British origin of the spotting rifle accounts for the British headstamp (RG for Radway Green) on the round shown below. The round illustrated is only a tracer loading. A spotter-tracer loading is also made.
The round consists of a necked-up 7.62 x 51 case fitted with a lead projectile, gilding metal cap and a trace cannister at the rear. The parent case has been modified to accept a .22 Hornet case which holds the powder charge and is crimped and sealed..
The only headstamp which is legible is the one on the .22 Hornet case which is: RG 83.

Paul added the following information and photos, thanks to an anonymous source:

"The Shoulder-fired Multipurpose Assault Weapon (SMAW) system was managed by the Navy lab at Dahlgren, VA (NSWC Dahlgren Div) for the Marine Corps at Quantico, VA. The cartridge was therefore assigned nomenclature in accordance with Navy practices and bears the official designation of Mark 217 Mod 0.

Quite interesting about this cartridge is the fact that the 9mm spotting rifle operates semi automatically by means of primer actuation. In this concept the primer sets back rearward upon firing to unlock the breech bolt. Fired 9mm spotting cases look rather peculiar because the 22 Hornet case backs out about 1/4 inch. This idea of primer actuation was conceived by John Garand (who was a notable Canadian by birth). Garand experimented with several prototype semi automatic rifles using primer actuation in the early 1920s while at Springfield Armory. Some specially primed cartridges were loaded by Frankford Arsenal for Garand's experiments but he abandoned the idea in 1926 when he learned that the Ordnance Corps had decided to secure primers in the case as a general practice by means of mechanical crimping, such primer crimping being required by machine guns.

Engineering for the SMAW and its 9mm spotting rifle was performed by Royal Ordnance people in UK. They deserve a word of recognition for having successfully fielded a primer actuated small arms weapon in US military service. John Garand would be proud to know that his idea had sufficient merit to eventually be fielded.

Here are photos of the MK 217 cartridge carton and a photo of the fired case showing the primer set back about 1/4 inch, enough to unlock the spotting rifle's breech."