Kinda funny where this started and where it went…
Two questions, please:
What is “base bleed”?
What does “IVF” stand for?
This sounds like something I should know, but…
Base bleed is not unlike a tracer. A pyrotechnic mixture burns and creates gases ejected at the bottom of the projectile. These gases reduce the atmospheric base drag that acts on the projectile.
Compared to tracers, base bleed elements are not for visibility of the trajectory, but are optimized for gas production and thereby reducing air drag and extending the range.
On the other side, the base bleed element takes up space that would otherwise be filled with explosive. And it increases dispersion, due to little differences in burning from shot to shot.
Edit: Tracer bullets also have increased dispersion for the same reason.
IFV - Infantry fighting vehicle
Base bleed - a specially designed projectile to include in its rear part a cavity, similar to that of a tracer, that includes a slow burning compound intended to project some gas outward, enough to reduce the drag created at the back of the projectile, due to the low pressure area.
While IFV should be quite a frequent acronym on the internet and wherever, base bleed is quite a niche thing for artillery geeks, so you don`t need to worry.
Yup, IVF, should’a known that, but when I was in service, we just called them ‘death traps’…
In my view a very good thread!!!
Not being a big bore military collector & having only served in the USAF I can use some help with “OTO”.
This is OTO Melara, the Italian company that designed the 76mm auto gun (mainly for naval use).
The US Navy is using it too.
The company today is the Leonard Holding:
An extract from my forthcoming book: Autocannon: the History of Automatic Cannon and their Ammunition
The 60mm system was developed as a result of an agreement between Israeli Military Industries (IMI) and OTO Melara of Italy, now part of Leonardo- Finmeccanica’s Defence Systems Division.
This project started in the late 1970s for a new kind of gun for light or medium AFVs, primarily designed around a high performance APFSDS round intended to penetrate earlier generations of main battle tanks and the side armour of contemporary ones. It was proposed for rearming older tanks as well as equipping new vehicles. IMI referred to the gun as the Hypervelocity Medium Support Weapon (HVMS 60) while OTO Melara, who had been thinking along similar lines, called it the High Velocity Gun System (60 HVGS). Initially, IMI were expected to develop the gun and ammunition, and OTO Melara the turret and autoloader. However, in the event both companies went their own way in developing the systems, although they retained the same cartridge case dimensions.
The IMI HVMS 60 has a vertical breech-block, electrical firing and a hydrospring recoil system. The gun weighs 700kg of which 500kg is the recoiling mass (recoil distance 27cm). The barrel is L/70, the overall gun length including autoloader is 510cm. Two types of loading system were originally being developed for this system, one recoil powered and the other hydraulically power-assisted. The recoil-powered system has two three-round magazines mounted on the gun, permitting firing of a three-round burst in three seconds or semi-automatic fire. IMI also developed a prototype two- person turret for this weapon, weighing about 2,200kg, which for trials purposes was installed on an M113 APC.
The OTO Melara 60 HVGS also uses a vertical sliding breech block, an elec- trically actuated firing system and a hydrospring recoil system with a 27cm recoil movement. The barrel length is the same, but the gun weighs 1,000kg. It is fitted with a dual automatic loading system capable of loading and firing at any gun elevation with a rate of one round every two seconds. The electrically-operated loading system uses twin magazines holding 32 rounds in total, with reloading possible from inside the vehicle. OTO Melara developed the T 60/70 two-person turret, which can be installed on a wide range of tracked and wheeled vehicles. In mid-2000 the OTO Melara T 60/70 turret was shown fitted to the IVECO/OTO Melara VCI (8 × 8) being developed to meet the operational requirements of the Italian Army.
Incidentally, the 60 × 410R ammunition was developed from the 76.2 × 580R round for the US Army’s post-World War II M32 gun, used in the M41 light tank.
After all of this work, the only customer for the system was Chile, which bought a manually-loaded version of the IMI gun for rearming its (ex-Israeli) M50 Sherman tanks (sometimes designated M60), and a version firing a three-round burst to their M24 Chaffee light tanks, which were in service for the last decade of the 20th century. Subsequently, the Chaffee gun was installed in a Chilean-built Piranha 6x6 light AFV, but it is unclear whether or not this saw service.
(and some further info on OTO from the book):
Concerning the origin of the names OTO Breda and OTO Melara: OTO (the name dates from 1929) stands for Odero Terni Orlando, Odero and Orlando being two of the founders of the company, and Terni being the location of the original factory. Breda and Melara are the names of other factories, located in Brescia and La Spezia respectively. In 1992 the company became part of Finmeccanica S.p.A., and in 2001 the naval gun division of OTO Melara merged with Breda Meccanica Bresciana to form Otobreda. In 2016, the company became a part of Leonardo-Finmeccanica’s Defence Systems Division; the company is now known as Leonardo S.p.A…
Tony, thanks again!
Do you have a publication date for your new book?
It’s supposed to be published sometime next month, although that’s looking optimistic…
Very good to hear!!!
Basically it is close so 1-2 months more will not make a big difference I guess.
Sounds like an interesting read… I might be interested in a copy, (but only if it is autographed ).
Sadly, autographing copies isn’t really feasible. I don’t sell or post my books, except potentially in person at British ECRA meetings, but the publishers (The Crowood Press) might offer a discount for direct sales.
I just received this response about the book from your publisher, but they did not tell me where it would be available:
AUTOCANNON 9781785009204 will be available in the USA In October 2021. Sterling price is £50.00
The Crowood Press”
Just keep saving the extracts that Tony posts
That’ll keep you busy… 200 different cartridges and 400 guns described, plus c. 500 pictures.
Got this info from publishers today:
" Good morning Jack
Our USA distributors Motorbooks International/Quarto have only received information about this book this week. They will not be announcing this book until December 2021 at the earliest.
Once they have stock I will forward your enquiry on to them.
The Crowood Press"