20x110 Hispano "BBC 1941 20mm"


#1

I think this is a 20x110 Hispano. What is BBC (outside of radio circles)?


#2

BBC = Bridgeport Brass Co. Bridgeport, CT (1941-1942)
M21 (20x110 Hispano)


#3

[quote=“sksvlad”]I think this is a 20x110 Hispano. What is BBC (outside of radio circles)?
[/quote]

  • @ sksvlad: To me it looks like a 20X110RB Oerlikon “S” shell case, not a 20X110 rimless Hispano. Please measure de head diameter: 22.1mm for 20X110RB Oerlikon “S” and 24.7mm for 20X110 rimless Hispano. Let me know what exactly you have. Liviu 04/11/11

#4

Diametre is 24.5mm, my manual calipres, I guess it is 24.7mm with better measurement. Here is a side scan.
image


#5

Not sure why this post is now revived but the Hispano is a semi-rimmed case and the Oerlikin has a rebated rim

Sort of the biggest sub-machine gun as it fires from an open bolt


#6

Sorry, Pete, I am going through my old posts and removing the links to Photobucket. It is simple to do but can ONLY be done to your own posts, not to someone else’s. One just copies a photo (even if it is distorted), goes to “edit” button which looks like a pencil, erases the old photobucket link and pastes in the copied image. The picture now comes from IAA storage server, not photobucket’s.
Every time you perform this, the system thinks it is a new post and puts it on top.
So when I kick the photobucket, my pictures will still be here with you.


#7

Pete, there were much larger calibers using the API blowback breech system.


#8

Pete, there were much larger calibers using the API blowback breech system.

The biggest I know of was the 57 mm T78 low-velocity aircraft cannon, a slightly modified US version of the 55 mm Rheinmetall-Borsig MK 112.

The biggest to see service was probably the same company’s 30 mm MK 108. The IJN also tried in combat the 30 mm Type 2, using ammo very similar in appearance to the MK 108, but this was never officially adopted.


#9

Tony, I think the Russians had 57mm types also (experimental).
And about the 76mm NS-76 I am not sure now. Would have to digg docs to check but that will take too long.


#10

Why has the rim on the cartridge case, shown above, been completely removed?

Sksvlad do you remember at what location on the cartridge you took the measurement?

Brian


#11

Brian,
I’ll find it and re-measure it when I get home. I posted this a long time ago. I don’t remember what I’ve done.


#12

Mystery solved, the above whole round image was a scan, and it did not pick up the rim. Here are photo shots. Notice no flash holes.


#13

No case mouth crimps, so the bullet has probably been put into an unfinished case. Dummies almost always have case holes.
And I think a wrong bullet.