Is is 75mm, 76mm or 3 inch?

[DEADLINE222]

For the life of me folks, I cannot figure this (what I assume to be common) projectile out.

I have conflicting information comming from various pictured projectiles on BOCN, various other sites, ORDATA and TM-1901.

First, note that the ROTATING BAND IS NOT ORIGINAL, as I placed it there several years ago. (I plan to machine it to the proper specifications whenever I acquire a bigger lathe.)

The projectile is 13.22 inches long and my seemingly inaccurate scale puts it's weight at 12-13 pounds.

I see pictures of projectiles painted as either 75mm, 76mm and 3", yet none of their rotating band's size matches my example.

The projectile's rotating band is .750" (3/4")wide, and fits perfectly in the recessed area machined for it.

The base fuze threading is 1.500" wide.

Using TM-1901, I had thought I had found a match, but it states that the rotating band for APC M61 is only .49" wide.

Please, do help me!

 

[raymeketa]

Looks like a 3" AP.

Ray

 

[ordman]

p { margin-bottom: 0.08in; }
My opinion it's a 3 APC but could be a 76MM
The rotating band is someones attempt at reproducing it
May be just sleeved on there
The band is to thick
Does it come off?
If so it's a re-pro of some type
Check on the body for stamps

 

[DEADLINE222]

Based on the rotating band size on the pictured 3" AP MK29; you could fit 11 3/4 of the above pictured projectile, across the pictured projectile.

Once again, my projectile is just over 13" long, and the rotating band is .750" or 3/4" wide.

That means you could fit 15 1/2 of the .750" rotating bands on my projectile, across my projectile. (Unless the rotating band overlaps onto the body of the projectile.)

Also, from the base of my projectile to the bottom of the rotating band is also .750" or 3/4".

Did they make varied sizes of rotating bands for the 3" AP MK29?

 

[DEADLINE222]

p { margin-bottom: 0.08in; }
My opinion it's a 3” APC but could be a 76MM
The rotating band is someones attempt at reproducing it
May be just sleeved on there
The band is to thick
Does it come off?
If so it's a re-pro of some type
Check on the body for stamps

See line #3 in my initial post:

"First, note that the ROTATING BAND IS NOT ORIGINAL, as I placed it there several years ago. (I plan to machine it to the proper specifications whenever I acquire a bigger lathe.)"

And no, it does not come off.

I made the band to fit perfectly into the cut where the original was placed. It is a piece of machined steel I wrapped around, and welded the ends together.

And yes, I know the rotating band is too thick. I acquired this projectile in my early days of collecting.

There are no markings or stampings.

 

[HAZORD]

It is a U.S. Army 3 inch or 76mm APCBC-T projectile. They used the same projectile for both guns since it is the same diameter. Was used in the 3 inch M10 Tank destroyer or the 76mm super sherman. Navy APCBC-T projos are shorter. They used them in the Battle of the Bulge and in the Pacific, specifically to shoot above the mouths of caves used by the Japanese, to close the caves.

 

[raymeketa]

Deadline222

You indicated you were planning to shape that rotating band after you get a lathe big enough to handle the projectile. May I make a suggestion? Why not go all the way and replace the steel with a copper ring? I have done this on a couple of fired projectiles and when you are done you cannot tell the difference from an original. It takes a little more time and the expense of a piece of copper big enough to work, but it's well worth it, IMHO. It involves turning the base of the projectile and installing a sleeve but it's really not very complicated once you figure out how to do it. I'd be happy to tell you how I did mine. Email me if interested.

Ray

 

[HAZORD]

Another option that doesn't involve turning the steel off the tail end of your projo, is to go to the scrap yard and get a piece of copper strip thick and wide enough to be the rotating band. Use a band saw, and cut the strip into the width of the rotating band. Wrap the strip around the projo (takes a vise and a hammer. Bring the ends together and have someone Tig weld the ends of the strip into a complete band (will take a lot of preheat because the copper pulls the heat away), and then turn the finished piece on a lathe.

An alternative method, is to wrap a strip around the projo, filling the rotating band groove up to the diameter of the projo body. Make up a copper sleeve the outside diameter of a completed rotaing band, and heat shrink it over the strip you used to fill the groove in the body, or solder it to that strip. Then turn the OD.

 

[raymeketa]

If you decide to go the TiG weld method, make sure you use pure copper. Most of the copper alloys do not weld well, although they can be soldered or brazed. But then you end up with a joint that is visible.

Ray

 

[DEADLINE222]

It is a U.S. Army 3 inch or 76mm APCBC-T projectile.

Copy the advice on the rotating band guys, I will refer here when I get a bigger lathe. That could be a bit down the road.

What I would reallly like to know is what model this projectile is?

The first thing I have to ask: Is ORDATA or the TMs always accurate?

TM 9-1901 says that the diameter rotating band for the 76MM M62 is 1.02". My rotating band is .750". So how can my projectile be the M62?

All 3" rounds detailed in TM 9-1901 also have 1.02" diameter rotating bands. Once again, my rotating band's groove is .750".

DO THE ROTATING BANDS EVER OVERLAP OUT OF THE MACHINED GROOES ONTO THE BODY OF THE PROJECTILE?

In TM 9-1901 all 75MM projectiles described in detail have .49" rotating bands; specifically the M61.***

Furthermore, here are some pictures from various BOCN threads that have identified models in which the rotating bands are too big; the 3" being stamped on the rotatig band per the owner.

***The picture contaning the multiple cartridges with the 75MM M61 looks to have a .49" band -making mine too big to fit.

If I am overlooking something simple; bare with me. I am still digesting dinner, and the kids are acting like monkeys.

 

[DEADLINE222]

If I am overlooking something simple; bare with me. I am still digesting dinner, and the kids are acting like monkeys.

Ok.

My bad.

I purchased this projectile in the few first weeks of my inert ordnance collecting, which was 7 years ago. It was also my first attempt at "restoring" a rotating band.

I did not know what I was doing, and I was foaming at the mouth for complete cartridges. Since then, this projectile sat atop a 3" /50 caliber casing until a few days ago.

Today, I started to closely inspect my rotating band and found that it does indeed overlap onto the body of the projectile; making the grove .49", and not .750".

Once again -my bad.

Earlier today I purchased the better part of a genuine, factory stamped M61; which I think my projectile is because of the sizes of rotating bands per TM 9-1901.

However, I noticed that all of the pictures I can find of the M61 have different numbers of ballistic cap crimps than mine, which is 6 crimps/indentations. My genuine M61 has only 3 indentations, as do all of the others I have seen thus far.

So, I am wondering. If my projectile is an M61, what modification number it is? -Assuming this applies.

The reason I am bent on the this projectile being a M61 (not the possible 76mm or 3 inch) is because of the picture of the gentleman holding the fired projectile. (You will need to save the image and zoom in really close to see.) If you look at the one in his hand you can see that it would have only 3 indentations on the projectile, whereas the multiple projectiles on the table clearly have 6.

What gives?

Genuine projectile is base marked: 1942 B.S.CO. 75MM A.P. M61 LOT 8869-10 *Manufactured by Bethlehem Steel Corporation as pictured in the right image*

 

[DEADLINE222]

Since I now have an M-61, we will make it an M-61A1 and call it a day.

Apparently my lathe will handle a 75mm projectile after all. The rotating band is steel with copper paint.

On to the next one....

 

[US-Subs]

The first thing I have to ask: Is ORDATA or the TMs always accurate?

DO THE ROTATING BANDS EVER OVERLAP OUT OF THE MACHINED GROOES ONTO THE BODY OF THE PROJECTILE?

View attachment 53942View attachment 53943

ORDATA is the Wikipedia of the ordnance world. It is put together with information collected from technical documents in order to disseminate minimal information rather than give out full pubs to contractors, etc. It is not a reference by iteslf, and is not used as one by the professional community. It is a decent source if it is all you have, but generally you let it lead you to an ID, then get a real publication. Even TMs have errors, but they are normally a primary source of data and are much more accurate than collections developed for general purposes.

In regard to rotating band overlap, no, not in my experience. What would be the point? The RB seals the gasses and transfers the rotation from the barrel to the projectile, via the point where the band meets the body (RB Seat). Anything beyond this is extra and I would imagine wasteful.