Us prototype roller ball fuzes


Small collection of fuzes from the estate of an ordnance worker. Roller ball safety type for 20,37 and 57mm shells. Unmarked. No further info. Mellichamp says the 37mm looks like a project from the 30s. It is in a 1945 M16 AT gun case. Who knows ? There is a current US 20mm fuze which is similar. 37mm type is steel. All others are aluminum.


That aluminum one cutaway on the black pedestal/57mm shell is the M86E1. Formerly designated as T86.


Yes,thank you, you are correct. Do you think that the 37mm version could be a step in developing something for the Vigilante system like the T231E3 for example ?


Entirely possible but unless the documents show up we are guessing. The “rotor” design was used in many US fuzes as you already know. There were nose fuzes with two of these rotors and also base fuzes existed which were using this system.
It was even tested with cal .50 fuzes (T253) where the rotor held no detonator but served just as a valve in the flash channel.

Check on “MIL-HDBK-137” Fuze Catalog, Vol 2 Obsolete and Terminated Fuzes, 1970


Thank you, I have done that. I have never seen any of the .50 fuzes . What is your idea for a time period for these fuzes ?


The M86E1 was likely a late WWII development or short after so I assume an investigation on the earlierst adopted fuze using this system will give us a lead on the adoption period.

Checking on patents will certainly bring more details but this will be very time consuming since it might be hard to search for this detail.


There are 3 variations of the 57mm fuze including the T86 in this lot. Although type classified I have never seen the M86E1.


The M86 Fuze can be found in TM9-1901 Artillery Ammunition, 1950, pages 318-320. I tried to do a copy and paste, but it wouldn’t work for some reason. As can be seen by the Doctor’s pictures, it’s for the M303 57mm HE-T round that is on pages 107-108 of the same pub. It’s interesting to note that the fuze before it and used in the same 57mm round, the M85, is a take off of the M56 fuze used in the 37mm M54 HE-T Projectile, just as this fuze is a take off of a 37mm fuze.


Thanks. Do you see the difference between the M86 and the M86E1 ?


Dr., The only difference I can see between the fuze you have pictured and the M86 drawing in the pub is that the cavity holding the Spring Lock Wire is shallower and the wire is shorter, causing the booster cavity to be squared off (full bore) whereas yours is in the form of a truncated cone (to add more structural strength for the deeper cavity). Incidentally, the fuze drawn in TM 9-1901 (1950) is stenciled “FUZE PD M86, 46-P-45”, which I assume means a 1945 lot number, which may answer the fielding question. I have the “T” version of the 57mm at home and I seem to remember that the lot stamped on the rotating band is mid '44.


Thank you for the analysis. I will post all 3 types later when I get a chance to take more photos.