30x173mm and 35x228mm projectile dimensions

Newbie here,

This forum seemed like the best place where I might get help on information I’m trying to get, but I didn’t had any luck yet. I’d like to know if it’s possible to get the dimensions or technical drawings for the 30x173mm and 35x228mm calibers. I have the shell casings in my collection since a long time, and I’d like to 3d print some fake projectiles to make the round complete. Searched on the internet and could’nt get what I was looking for.

Any help given will be greatly appreciated !

Thanks in advance.

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I have examples of these cartridges but no drawings or means of producing any. I can take photos but that’s the best I can manage.

Thanks for your reply;

Pictures with a ruler next to it would be great.

I’ve found this topic : 50 mm Oerlikon which has some nice drawings at the end, that would be perfect if I could get my hands on the same drawings but for the calibers I’m looking for.

Here a 35x228 HEI.

35x228_HEI_Mi%20Br%20G%20MZ%20Flab%20Kan%2063

Excellent ! Exactly what I was looking, for ! Thank you very much ! Ill try to post pictures here of my project.

OOOPS! My mistake.

Alex is correct, wrong 30mm cartridge/projectile.
That’s what happens when I get in a hurry. Images deleted so as not to confuse the focus of this thread.

Brian

Brian, interesting! I was not aware that Amron made 30x170.
Do you happen to know the case material of their rounds?

Two questions regarding the drawings :

For the 35mm projectile, the diameters are showing only negative tolerence differences, how come ?

And does the 30mm drawing is valid for a projectile that’d be fired from the gau-8 canon ? My casing comes from an A-10.

Thank you again.

Somehow I initially read you were looking for a 30x170 and for some reason Brian did too.

For the 30x173 GAU-8 you will need a different drawing.

When you are living in the US it should be very easy to find such a projectile in online sales.

Negative tolerance only means the number listed is the absolute upper maximum and you can vary smaller by the amount listed.

It’s a different way to say a number plus or minus, but giving preference to the upper bound because in the end you still have a range that’s acceptable

Upper bound is important for projectiles because you don’t want them bigger then that number at all

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I believe you need to know the ogive radius to create the correct head and fuze shape.
If I got my math right, the ogive radius in EOD’s drawing for a 110 mm high tangent ogive with a 4.8 mm meplat would be 408.47 mm.

Thanks for all the useful answers. It’s a project that popped in my mind as the casings were sitting on my shelf since a long time. The 30mm one I can get from some stores (thx for the advice by the way) but the 35mm I wanted to get it machined. On a side note, I don’t know fully understand what the ogive radius is ? I am new to this kind of science to say the least. I’d need to know the rotation band height also…

Thanks !

If you look at EOD’s drawing, you see that the middle section of the projectile body is practically cylindrical with 34.98 mm diameter at the front (110 mm below the nose) and 34.94 mm at the beginning of the boattail (the rear part).
The part in front of the cylindrical section shows a shrinking diameter until it reaches the flat nose (called meplat) of only 4.8 mm diameter. At first sight it looks like a truncated cone, but it really isn’t. If you put a ruler alongside the outer shape of the projectile (110 mm line to meplat) you see that its not straight but curved. As a matter of fact, it is a segment of an ordinary circle. It is the dominating element in projectile design.
In this case, the circle has a radius of 408.47 mm. The center of the circle is located 110 mm below the meplat and 390.98 mm to the right/left of the center line of the projectile (408.47 mm minus 17.49 mm projectile radius).
As soon as you start to model the projectile shape for printing it in 3D (or make a drawing for a machinist), you will see the above numbers falling into place.
The name “ogive” actually come from architecture. If you look at a gothic cathedral, for example, the typical windows of that style have a pointed top. The window top shapes are also created by using circular lines as construction elements.

P.S. Writing this response I noted that the end diameter of the boattail is also missing from the drawing. It seems to be about 30.9 mm, comparing it to the 34.94 mm line. (Interpolating dimensions from drawings this way should never been done in serious work, by the way.)

Ogive:

Radius:

Thanks to you all for the quick answers ! I now have the tools in hand to start my project !

Hello ! Here is the completed projectile thanks to one of my friend talents in cad drawing and 3d printing. The tolerences are perfect and it sits tightly on the casing. I’d like to do the same for my 30mm casing, if anyone has the drawings on hand… I can’t ship projectiles to my country unfortunately…

Very smooth surface! Must have been a good printer I assume.