Below are 3 photos of sectioned 37x137mmR cartridges and headstamps from the 1916 dated Russian manual for the McClean gun.
PE&MCo. = Poole Engineering & Machine Co, the cartridge case is dated June, 1916
U.M.C.Co. = Union Metallic Cartridge Company, the cartridge case appears to be dated June, 1914
Another U.M.C.Co. headstamped cartridge case, dated November, 1915
One very obvious difference in the sectioned rounds is the variations in the primers.
Below is the complete manual, unfortunately divided into 4 PDFs in order to be able to load it here on the forum:
R37a1.pdf (4.8 MB)
R37a2.pdf (4.2 MB)
R37a3.pdf (3.8 MB)
R37a4.pdf (4.8 MB)
PS: Forum member SKSVLAD when asked to try to translate the ammunition section, pages 24-26, of the above posted manual he graciously accepted the challenge. Because the text is an old style of Russian Cyrillic Vlad soon realized it was going to be an arduous task but he persevered and was finally able to complete the task at hand. So, thanks to Vlad, we now have the translation of the Russian text describing the 37mm ammunition for the McClean gun shown at the end of the manual and the same pictures are posted above:
37mm Auto Cannon System McClean
Chapter V - Ammunition
McClean 37mm cannon was assigned one round with a steel grenade. The cartridge consisted of: grenade projectile with a detonator, the shell (cartridge), the charge (propellent) and the primer.
1. Grenade (warhead)
The grenade consists of outer shell (body) (1) with threaded bottom (2) into which the detonator screws in. The body of the grenade is made out of steel and it has a continuous copper rotating band. The main charge (3) consists of 3 1/2 zolotnikov of coarse rifle black powder load. The un-armed grenade without detonator tube is approximately 94 3/4 zolotnikov. The weight of fully armed grenade with detonator is approximately 1 pound 16 1/2 zolotnikov.
2. Detonator tube
The bottom thread installed detonator consists of: brass body (A), brass bushing (Б) with an anvil and a primer, striker (B) with a firing pin and a safety sleeve (Г). Brass bushing has a steel spring loaded safety device, two fingers of which hold the neck of the striker to keep it in place. During firing the two safety fingers break due to the centrifugal force of rotation, and this frees striker’s neck so it hits primer with its firing pin during projectile’s impact. When the primer explodes, the flame tongues exit through 2 flash holes towards the main explosion charge (3).
Cartridge: brass, drawn from one piece. Its weight: about 37 zolotnikov. Length: 5,36 inch. The projectile is inserted into the cartridge’s mouth contacts the rotating band of projectile. At the bottom of the cartridge there is a well for eitheer primer or and ignition fuse.
4. Primer and ignition fuse primer.
There are three types of fire delivery to the main propelling charge in McClean cannon cartridges.
1. Primer with anvil within a brass sheath (a) which is inserted into the well of the cartridge (Plate XIV picture 1). To enhance fire projection of such a primer, an igniter (б) of 1 zolotnik 15 doli weight of rifle black powder is placed at the bottom of the cartridge, poured between two paper material discs of 1 1/2 inch diameter, stiched along the circumference.
2. Into the primer well installed a small ignition fuse (a) with the length of 1.05 inch, and this fuse’s bottom has a primer with an anvil, and from the other side (top) a fine black powder rifle charge (б) is placed in the amount of 24 doli (Plate XIV picture 2). The black powder is covered with a carton disc and the top edge is crimped. With this type of ignition no additional ignition charge is required.
3. Bottom ignition fuse (a)
The same construction as in above discussed #2, but the greater length is 2.05 inch this longer fuse takes 63 doli of the same fine rifle black powder (б) (Plate XIV picture 3). Again, no additional ignition charge is required.
5. Main propellent charge.
Propellent charge is made of smokeless gun powder molded as a tube with a single central channel, it comes in two types…
1. Propellent charge of 20 zlotnikov
Outer diameter of gun powder is 1.57mm
Inner diameter is 0.56mm
Thickness of the wall 0.55mm
Length of gun powder grain is 7.0mm
With this charge a No.1 primer is installed into the well and a separate ignition fuse is placed at the bottom of the cartridge (Plate XIV picture 1)
2.Propellent charge of 16 zolotnikov 72 doli.
Outer diameter is 1.25mm
Central channel diameter 0.33mm
Thickness of the wall is 0.47mm
Length of gun powder grain is 6.0mm
With this type of gun powder a primer with ignition fuse is installed (Plate XIV pictures 2 and 3). No additional ignition charge is needed.
The main ignition charge, after being poured into the cartridge, is covered on top with a felt disc (M) (Diameter 1.4 inch, thickness 0.25 inch) with paper liner glued to the both sides of the felt disc.