Jawasinger
Well-Known Member
Help trying to determine between a 40mm M81 and a 37mm M56 any extra photos will help
British Ordnance Collectors Network
This is a sample guest message. Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!
40mm M81 APC
- Thread starter Jawasinger
- Start date
The M54 37mm projo is a nose-fuzed HE boat-tail shaped projo, the M59 37mm projo is capped with no windscreen. The 37mm M51 series projectiles are APC style.
The M81 40mm AP-T without windscreen is 4-1/8" long, but the diameter doesn't look to be as reduced as much as on your projectile. The windscreen is very thin, and that is all that is turned off of the slug for the windscreen to be crimped on. None of the 37mm projos have a long reduced body section for a windscreen. Yours looks closest to the 40mm M81.
The M81 40mm AP-T without windscreen is 4-1/8" long, but the diameter doesn't look to be as reduced as much as on your projectile. The windscreen is very thin, and that is all that is turned off of the slug for the windscreen to be crimped on. None of the 37mm projos have a long reduced body section for a windscreen. Yours looks closest to the 40mm M81.
Last edited:
Jawasinger
Well-Known Member
Thanks Hazord the real argument between another fellow and I is I say 40mm and hes says 37mm I didnt have any pubs over a M56 I personally have 2 40mm's with windshields and one projo without like this but he wont just take my word
Jawasinger
Well-Known Member
yes you would think this would be a simple solution.... the projo body is 37mm but the diameter of the rotating band is 40mm
Chris 42 RQ
Well-Known Member
As Chris says !
The actual calibre of a weapon is usually measured from the smallest diameter across the "lands" (the rifling) so the driving band will need to be larger in diameter than the steel shot/shell in order to impart rotation and effect an efficient seal.
For an absolute measurement you can take a measurement across two opposing flats on the band making sure you have an "even" number of flats engraved thus ensureing an accurate reading.
The actual calibre of a weapon is usually measured from the smallest diameter across the "lands" (the rifling) so the driving band will need to be larger in diameter than the steel shot/shell in order to impart rotation and effect an efficient seal.
For an absolute measurement you can take a measurement across two opposing flats on the band making sure you have an "even" number of flats engraved thus ensureing an accurate reading.