OT- Mystery cartridge ID

In a box of non-firearm-related junk, I found a strange cartridge case. Not sure if all of it is actually cartridge-case, or if it has an extraneous object jammed into it.

Dimensions, rim diameter .598"
Body diam next to rim .490"
case mouth OD .447"
Overall length 1.968

(both last dims do NOT include the "teeth"

Headstamp "ST MK 15 MOD. 1
44 135 M"

Boxer primed, primer shows a small, slightly off-center hemispherical impression.

Can anyone tell me what it is?

Thanks!

Possibly a 45-70 blank perhaps for line throwing guns.

That stuff sticking out doesn't look like part of the case. Could it be part of some kind of wadding or even sticks of cordite propellent?

It's a blank.

It is a primer for a navy gun. This was used with a bag charge of powder, like the big 16" guns on the battleships. Gun was loaded with projectile, then multiple powder bags, the breach was closed and the primer was inserted into breach. We still use them for 155mm and 8" Army guns. They are based on a .45-70 case, the teeth were crimped over the primer powder charge so there was no wad to interfere with the flash.

MilGunSmith,
How much pressure is the "primer" subject to? I would have thought the "big guns" worked at enormous pressures. Maybe the primer is heavier than a standard 45/70?

WWII 16 in guns, run around 38,000 PSI, later era supercharges may have been developed .

Few WWII guns ran much over 40,000 PSI..

No enormous pressure, just enormous area for pressure to push against.

I seem to remember the Army 8 in howitzers I worked on, using a cartridge approx 38 S&W for primer.

Navy 16 in guns, would surely have used a bigger primer..

This is a M82 primer for the 155 Howitzer these cartridges are 50 mm (1.968) in length and Milgunsmith was correct.

THANKS, Paracongo and Milgunsmith! Maybe I should look in the box again and see if the rest of the 155 is down there.

magneticanomaly said:

THANKS, Paracongo and Milgunsmith! Maybe I should look in the box again and see if the rest of the 155 is down there.

Click to expand...

That's funny you mentioned that, last Thursday night at my weekly trap shoot a guy brought a 155 mm timed fuze, inert of course to see if anybody knew what it was.

Hi,

I can confirm that this is a primer for a "Breech Loading" or "BL" gun that used a bag charge and a breeech seal. In the UK these are known as "Tubes". I have come across many of this type used in the M107, M109 and M110 howitzers we used up to a few years ago.

The one in the picture looks like the electrical version because of the insulator around the central pole piece. The dent is from the connecting needle in the breech. This was common on Naval and coastal guns where fire was controlled from a central director. Land versions tended to use a percussion primer as it was more reliable in the field and the guns were fired individually.

Yes, there is a significant back pressure on Artillery primers.. they have to be designed to withstand this. Electrical primers achieve a rearward seal by having a shoulder machined on the pole piece. This is allowed to set back against the insulator under the gas pressure froming a seal.

Percussion pimers/tubes have to contain either a striker plug or a one way valve after the cap. The 105 M1 primer has a thick striker plug between the base of the primer and the cap. The striker in the breech hits the plug which is forced onto the cap. The back pressure overcomes the cap but is stopped by the thick plug which sits in a malleable sleeve. Other designs have a "ball in cone" or "cone in cone" one way valve between the primer cap and the gun chamber which allows the flash from the primer to pass, but blocks the back pressure from the chamber..

Hope this helps..