- Some projectiles have a few circular deep grooves machined between the copper driving band and the steel [or aluminum] ballistic cap. A projectile like this is the one made after 1945 and used for the Russian 37X252R round. — My questions are: A] Do those circular grooves have a specific name?? B] What is the purpose of those circular grooves?? Do they prevent the AP-T projectile to get deformed after hitting the target?? Thanks in advance for any help, Liviu 06/19/07
I can’t comment specifically on the Russian projectiles and I may be totally off base here, but a reduction in the diameter of a projectile forward of the rotating band is often done to reduce the area of contact between the bore and the projectile. This reduces bore wear.
- Thanks for your reply. The area of the projectile where those deep circular grooves are machined will never get in contact with the bore. I’m pretty sure the reason why those grooves were made is quite different. Thanks anyway, Liviu 06/19/07
The AP shell has pronounced grooves that help to control the compression of the shell on impact on hard armor.
- @ Rien: This is the answer I was waiting for. Do they have a specific name, I mean those grooves??? More pictures of those projectiles can be seen here at geocities.com/Pentagon/Base/1852/index2.html and click on “37mm Russian M1939 AAA” at 37X252SR and see the photo of the 5 rounds 37X252R. Both 37mm projectiles from right [green & black] have those deep circular grooves I was asking about. Liviu 06/19/07
these grooves are called “localizers” in Russian.
They serve the same purpose as the mild steel breaker-cap on APCBC (AP capped, ballistic capped) projectiles.
During armour penetration, the grooves act as a designated break area and limit the destruction of the projectile body in case the projectile encounters an armour plate close to, or in excess of its penetration capability.
The info from my webpage as stated above is a bit outdated, I am sorry for not being able to correct all those errors because of missing time.
- @ Rien & Chris: Thanks very much for the good info. Liviu 06/20/07
Really fascinating design engineering. Physics rule! Fantastic information.
- It was obvious that those deep circular grooves have a precise and important purpose, not only to make the projectile to look nice. Liviu 06/20/07