Grenade, Rifle, Fragmentation, Impact, M17



The development item for this grenade was the T2.  The M17 was adopted in 1941-42 around the same time as the M9A1 grenade.  It was declared limited standard and manufacture stopped by 1 May 1944 (OCM 23594 and 24015) at the same time as the loading of the Mk. II grenade was changed from EC Blankfire powder to TNT.


The main body was that of the Mk. II fragmentation grenade.  The stabilizer and fuze are the same as used on the M9A1 AT grenade and consists of the stabilizer tube, fins, and fuze mechanism.  The stabilizer tube has an internal diameter of 22 mm.  The fin assembly is made of three pieces of sheet steel bent into a “Z” shape with one long arm and then spot welded together to form the fin assembly.  The fin assembly is spot welded to the bottom end of the stabilizer tube.  The fuze mechanism is an impact fuze consisting of the fuze body, striker, creep spring, and safety pin.  The striker fits into the body and is held back from the primer by the creep spring and safety pin.  The fuze body has a reduced diameter at the bottom to fit into the top of the stabilizer tube and is retained in position by four small round headed bolts.  The upper end is threaded to screw into the thread reducing adapter.  The adapter screws onto the top of the fuze and is threaded at the other end to fit the body of the grenade.  The adapter contains the primer and booster charge.  The main grenade body is filled with 0.77 ounces of EC blankfire powder. 


The grenade was initially painted yellow with markings in black (this may have been the T2 version on trials).  After  October 1942 they were painted olive green with markings in black.  Later issues had the marking colour changed to yellow.  There was a yellow band around the top of the grenade head just in front of the tail assembly.


When the grenade is to be fired, it is loaded onto the launcher attachment and the rifle loaded with a launching cartridge.  The safety pin is then removed and the grenade fired.  The setback caused by firing along with the creep spring in the fuze keeps the firing pin from hitting the primer.  When the grenade strikes the target the firing pin overcomes the resistance of the creep spring and strikes the primer.  The primer fires into the booster which initiates the main filling.  The fuze would function on any impact which is sufficient to sharply retard its flight.  It might not function if it strikes with a glancing blow or on impact with water.


After May 1 1944, a project was initiated to change the loading of the M17 from 0.77 oz of EC powder to 2 oz. of TNT.  This required a modification to the fuze.  The booster was removed and replaced with a 13.5 grain PETN blasting cap that extended up into the grenade body.  Several TNT loaded grenades designated M17E1 were tested but the project was dropped in favour of the M1 adapter and grenade combination.

rifle grenade