US Artillery Fuze Sizes


This post is to clarify some questions brought up in the 155mm discussion. The fuze sizes for MOST of the US Artillery from 75mm on up for the treaded portion were about 2" measured from the tops of the pitch and with 12 threads per inch. There were exceptions to this rule when dealing with the WP rounds of 75mm, 90mm and 4.2". They were 1.7"x14 . For PD these would have been the M48 Series. Now, take that same fuze and add a booster adapter M21 series that has an arming delay and a healthy booster (gaine) on it and has the 2"x12 thread pitch, and you have the M51 series PD fuze. The Navy even used it in the Mod 3 version for 5" 38 Cal. All of this was to make things as standard as possible so we could mass produce as much as possible and get it to the front. If you look in the NAVSEAOP 1666/TM 9-1985-3 you’ll see what a headache the Germans had when dealing with fuzes and rounds. We kept with this standardization as much as possible till even now, with the M577/M582 series MTSQ and the M739/M739A1 PD fuzes.

 The M577 and M582 are almost identical but the M577 is used for "payload" rounds that have an ejection charge and the M582 has a booster screwed to the base so it can be used for HE and WP rounds.  This helps simplify production and procurement. 

 That's a starter to get discussion going.


Bruce is correct that modern fuze sizes have been standardized to a certain extent. But if you are collecting any of the older projectiles and wish to find a fuze to fit, it is extremely important to take careful measurements of the projectile and/or adaptor. There are at least 3 different sizes that fit most USN projectiles from the WW II years up until 1960 or so. Base fuzes require the same attention to detail, and maybe even more so, since many have left-hand threads.




Ahhhh. The old left-hand(LH) thread trick. Messed me up a couple of times. On a historical note, and waaaaaayyyyy off into foreign ord, the Japanese(WW2) were as apt to use RH threads on base fuzes and then just stake them on. Clever rascals. Saved on all that LH machine tool requirement, I suppose. Luckily, a couple of reference items on such make note of all those tidbits of detail. And, they didn’t bother with any sort of standardization to speak of.


Right hand base threads are perfectly OK if the ammunition is used south of the equator. :) :)


I KNEW I should have specified US Ground artillery. Just thinking of all of the different fuzes that the Navy used, what size rounds they went in, the difference in CAL, and what time of day or month you could shoot it in just gives me NIGHTMARES!! Indian Head in '83 was bad enough, but having to face an RSP test in Ground Ordnance and finding a 5" 38 Cal covered in mud with not only a nose but a tail fuze as well and then having to figure out what MK THEN the Mod got to be daunting. We Jarheads came up with a solution in the field. If it was Naval origin, cover it in fluid and call the Navy }:-)