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American 76mm but what type? Why the Hemi back end?
- Thread starter Kilroy
- Start date
Yes, it is a 75mm Skysweeper projectile with PD fuze. There are a number of postings here on BOCN about it.
In fact, you made a posting about the gun with photos of the ammunition in August a year ago. I'm confused as to why you are asking about it now.
http://www.bocn.co.uk/vbforum/threa...ith-the-round-nosed-base?highlight=Skysweeper
In fact, you made a posting about the gun with photos of the ammunition in August a year ago. I'm confused as to why you are asking about it now.
http://www.bocn.co.uk/vbforum/threa...ith-the-round-nosed-base?highlight=Skysweeper
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I have seen 30 mm ADEN Practice shells with a similar rear shape. Perhaps it is to reduce drag and give a more aerodynamic shape to the projectile.
"This may be an appropriate place to discuss hemispherical bases, their reasons, and faults. The Germans utilized them extensively in their high capacity "mine"-type HE and incendiary for two reasons (1) they were an easy configuration to make with drawn steel shell bodies, and (2) they provided maximum strength to resist chamber pressure in thin wall configuration. More recently we have used hemispherical bases to enhance fragmentation control and coverage from the shell base. So we have at least three good reasons for round bases. However, there is an overwhelming negative factor. Round base shells are far less stable than square base shells. A round base does not provide a clearly defined flow separation point. Given any degree of yaw, as the base of the projectile swings outward, the flow tends to adhere to the surface around the spherical base generating additional outward lift on the base which tends to increase yaw. Any shell designed today with a spherical base should have a skirt or trip ring to assure flow separation at the same point around the circumference of the base regardless of yaw."
Historical Development Summary of Automatic Cannon Caliber Ammunition.: 20-30 Millimeter - Dale M Davis
Historical Development Summary of Automatic Cannon Caliber Ammunition.: 20-30 Millimeter - Dale M Davis
I see your point...At various times I have been playing catch-up with the authenticity of things I had
sometimes purchased much earlier.
At the time I purchased the Skysweeper projectile, I was going on the veracity of the dealer. I had no
idea if it were truly a Skysweeper or not except the dealer said it was, and he was a reputable seller.
Over time, and with membership here and on other forums where there are people of superb knowledge
about virtually all aspects of ordnance, it has occurred to me ( sometimes years later ) on certain aspects
of rare or unusual ordnance to ask certain more specific or deeper questions.
As it happens at the moment, a steel lacquered case is for sale on Gunbroker, and I was wondering to myself
how, from a few alpha-numeric designations it can be determined that this was a Skysweeper case?
On that question, I am in contact with the owner of the case to see how he knows. Turns out, he does not know!
He is going on what somebody told him, but I am sure it will pan out.
The case number he gave is as follows: T6E3B1
This is what I have on my case I have here, and it was sold to me by a friend who did not know if it was a Skysweeper or not!
My endless obsession with this does not limit itself to the ammunition. I built the model, produced by Renwal, in the 60's
when the golden age of all types of military models was upon us. The Skysweeper captured my imagination, as it was
the only one of it's type and design, and I was utterly fascinated by it.
So much so that 35+ years later I had to go on a truly fascinating and years long trek to uncover and acquire this personal
Maltese Falcon type obsession.
The enjoyment was very absorbing to be on the trail of something you can look for over years and finally find it! The trip
takes you all over and you meet all kinds of people. It is the most exciting part of collecting!
If these numbers on the case sound correct, please explain if you can their meaning? I will save this info on T6E3B1
Danke,
Walt
It's too bad that there isn't a simple Rosetta stone for cartridge case markings, but all nations and eras have their policies on case marking.
First of all, if you go to this posting:
http://www.bocn.co.uk/vbforum/threads/41836-37-X-219SR-T68-Vigilante?highlight=skysweeper
I show two Skysweeper rounds, one each of steel and brass case. You can see the same model/part number on my cases as the one you mention. It has been explained a few times here on BOCN as to the method that the U.S. has used for marking artillery cases.
This posting was a reply to you as to the meaning of the B1 on the case to designate that it is steel.
http://www.bocn.co.uk/vbforum/threads/81255-Is-this-case-76mm-3-inch-or-what-!-!-!?highlight=model
The "T6E3" is the model design number that they assigned to the 76mm Skysweeper case, which was originally made by necking down a 76mm tank gun case. They evidently had a lot of the 76mm cases left over from the end of WWII and decided to pattern the chamber after that case.
The U.S. gives design numbers to everything including component parts. Up to WWII cases were marked "Model of XXXX, which was the year the gun was adopted that the case was intended for. When they started to experiment with new calibers, they adopted the "T" numbering system. T stood for "Test". Once a cartridge was tested and was adopted for Service, it received an "M" or model number. If the production quantity never exceeded a certain size, the "T" designation stayed and "M" numbers were never produced.
In the 1960's, the "T" system was replaced by "XM" which stood for experimental. The current method is to assign an XM number to experimental ammo, and assign an "M" number if the case is accepted for service and quantity production.
First of all, if you go to this posting:
http://www.bocn.co.uk/vbforum/threads/41836-37-X-219SR-T68-Vigilante?highlight=skysweeper
I show two Skysweeper rounds, one each of steel and brass case. You can see the same model/part number on my cases as the one you mention. It has been explained a few times here on BOCN as to the method that the U.S. has used for marking artillery cases.
This posting was a reply to you as to the meaning of the B1 on the case to designate that it is steel.
http://www.bocn.co.uk/vbforum/threads/81255-Is-this-case-76mm-3-inch-or-what-!-!-!?highlight=model
The "T6E3" is the model design number that they assigned to the 76mm Skysweeper case, which was originally made by necking down a 76mm tank gun case. They evidently had a lot of the 76mm cases left over from the end of WWII and decided to pattern the chamber after that case.
The U.S. gives design numbers to everything including component parts. Up to WWII cases were marked "Model of XXXX, which was the year the gun was adopted that the case was intended for. When they started to experiment with new calibers, they adopted the "T" numbering system. T stood for "Test". Once a cartridge was tested and was adopted for Service, it received an "M" or model number. If the production quantity never exceeded a certain size, the "T" designation stayed and "M" numbers were never produced.
In the 1960's, the "T" system was replaced by "XM" which stood for experimental. The current method is to assign an XM number to experimental ammo, and assign an "M" number if the case is accepted for service and quantity production.
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