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30x172
- Thread starter SG500
- Start date
Chris 42 RQ
Well-Known Member
Electric Primer.
Looks like an electric primer, so could it be for the "KBA" Oerlikon aircraft cannon ?
That is one of the few rounds that were electrically initiated I believe.
Chris :tinysmile_shy_t:
Looks like an electric primer, so could it be for the "KBA" Oerlikon aircraft cannon ?
That is one of the few rounds that were electrically initiated I believe.
Chris :tinysmile_shy_t:
pzgr40
Well-Known Member
On the WK-2 forum I got the message that I connected the wrong weapon (KCA)with this cartridge . So I looked a bit further and found the following info on Tony Williams site:
"Start Quote"
30x170
This was a Hispano-Suiza development from the 1950s, but has a connection to an earlier round as the base dimensions are exactly the same as the Hotchkiss 25x163, surely not a coincidence. The gun was originally known as the HS-831 but was renamed the Oerlikon KCB when the companies merged around 1970. It has exclusively been used in the anti-aircraft role, in both land-based and naval mountings. The cartridge cases were originally of brass but these are now rare, and steel cases are much more common.
In the late 1960s the case design was adopted for the British Army's Rarden AFV cannon, but the material reverted to brass. Rarden and KCB ammunition are not qualified as interchangeable.
30x173
Another cartridge with a complicated history, this was developed by Oerlikon in the 1950/60s for their 304 RK aircraft revolver cannon, later renamed the KCA. This only saw service in some versions of the SAAB Viggen fighter, which is no longer in use, although it was also offered in the Hughes Model 34 gunpod.
In the late 1960s the cartridge design was adopted for the American GAU-8/A 7-barrel rotary cannon, as fitted to the A-10 "tankbuster" plane and subsequently to the Goalkeeper naval CIWS. However, this differed from the KCA ammunition in three respects: the case material was changed from steel to light alloy, the priming from electric to percussion, and the driving bands from metal to plastic; as a result, the rounds are not interchangeable. Later still the GAU-8/A cartridge was adopted for the Mauser MK 30F cannon which is in wide use as an AA gun, and finally for the American Bushmaster II Chain Gun (renamed in its current, marinised, version as the MK44).
The most recent development by some manufacturers is a reversion to steel (but still percussion-primed) cases for the loadings specifically intended for AFV cannon, with the Mauser (now Rheinmetall) MK 30-2 being designed for these.
The 30x173 is now the most common Western cannon cartridge in this calibre, and is available in a wide variety of loadings, including APFSDS, from several different manufacturers. However, both the KCA and the latest AFV steel-cased rounds are hard for collectors to find, as is the GAU-8/A's notorious PGU-14/B API with a depleted uranium core (distinguished by a black and red projectile). Most cartridges available are of the alloy-cased TP type, with blue projectiles.
"End Quote"
So most likely this a cartridge for the Oerlikon 304 RK aircraft revolver cannon, later renamed the KCA, and the ancestor of the 30x173 Gau 8/A ammunition.
I should have browsed before I wrote my story.
I have also remeasured the length of the shellcase with a caliper; it is exactly 172,25 mm long.
Looking in the book " Small and medium caliber millitary cartridges part 1, these are consequently called 30x172, what in fact is more correct than 30 x 173. The rest fits in with Tony Williams info: steel shellcase, electric primer (see green circle in picture), and a steel driving band with a big groove (red circle) another feature is that the drivingband is one piece with the body. The shellcase in the drawing is from 1953, the one in my collection 1954, so the same time frame.
The fuze is really interesting;
Upon firing, the cap (3) housing a brass "crush-bellow" moves down -crushing the brass bellow-, overriding the spring (7). It enables the firing pin housing (4) which houses the firing pin(8) and it's spring (7) to move forward a little, releasing the ball housing the firing cap (10) and enabeling it to set itself in line with the firing cap. The four balls (5) in the firing pin housing fall into the groove in top of the brass ring (6) which keep the firing pin housing suspended as long as the force of the four balls in the groove (centrifugal force) is greater than the force of the spring (7). If no target is hit , the speed and rotation will decreaseup to a point where the spring forces the balls back into the firing pin housing , driving the firing pin into the firing cap, exploding the detonator (11)
If a target is hit, the desceleration will throw the firing pin housing (4) forward untill the armour is pierced and the desceleration stops. After piercing the armour -when the speed is constant-, the firing pin spring (7) will push the firing pin into the firing cap, exploding the firing cap and the detonator. The projectile will detonate after passing the armour.
With regards DJH
"Start Quote"
30x170
This was a Hispano-Suiza development from the 1950s, but has a connection to an earlier round as the base dimensions are exactly the same as the Hotchkiss 25x163, surely not a coincidence. The gun was originally known as the HS-831 but was renamed the Oerlikon KCB when the companies merged around 1970. It has exclusively been used in the anti-aircraft role, in both land-based and naval mountings. The cartridge cases were originally of brass but these are now rare, and steel cases are much more common.
In the late 1960s the case design was adopted for the British Army's Rarden AFV cannon, but the material reverted to brass. Rarden and KCB ammunition are not qualified as interchangeable.
30x173
Another cartridge with a complicated history, this was developed by Oerlikon in the 1950/60s for their 304 RK aircraft revolver cannon, later renamed the KCA. This only saw service in some versions of the SAAB Viggen fighter, which is no longer in use, although it was also offered in the Hughes Model 34 gunpod.
In the late 1960s the cartridge design was adopted for the American GAU-8/A 7-barrel rotary cannon, as fitted to the A-10 "tankbuster" plane and subsequently to the Goalkeeper naval CIWS. However, this differed from the KCA ammunition in three respects: the case material was changed from steel to light alloy, the priming from electric to percussion, and the driving bands from metal to plastic; as a result, the rounds are not interchangeable. Later still the GAU-8/A cartridge was adopted for the Mauser MK 30F cannon which is in wide use as an AA gun, and finally for the American Bushmaster II Chain Gun (renamed in its current, marinised, version as the MK44).
The most recent development by some manufacturers is a reversion to steel (but still percussion-primed) cases for the loadings specifically intended for AFV cannon, with the Mauser (now Rheinmetall) MK 30-2 being designed for these.
The 30x173 is now the most common Western cannon cartridge in this calibre, and is available in a wide variety of loadings, including APFSDS, from several different manufacturers. However, both the KCA and the latest AFV steel-cased rounds are hard for collectors to find, as is the GAU-8/A's notorious PGU-14/B API with a depleted uranium core (distinguished by a black and red projectile). Most cartridges available are of the alloy-cased TP type, with blue projectiles.
"End Quote"
So most likely this a cartridge for the Oerlikon 304 RK aircraft revolver cannon, later renamed the KCA, and the ancestor of the 30x173 Gau 8/A ammunition.
I should have browsed before I wrote my story.
I have also remeasured the length of the shellcase with a caliper; it is exactly 172,25 mm long.
Looking in the book " Small and medium caliber millitary cartridges part 1, these are consequently called 30x172, what in fact is more correct than 30 x 173. The rest fits in with Tony Williams info: steel shellcase, electric primer (see green circle in picture), and a steel driving band with a big groove (red circle) another feature is that the drivingband is one piece with the body. The shellcase in the drawing is from 1953, the one in my collection 1954, so the same time frame.
The fuze is really interesting;
Upon firing, the cap (3) housing a brass "crush-bellow" moves down -crushing the brass bellow-, overriding the spring (7). It enables the firing pin housing (4) which houses the firing pin(8) and it's spring (7) to move forward a little, releasing the ball housing the firing cap (10) and enabeling it to set itself in line with the firing cap. The four balls (5) in the firing pin housing fall into the groove in top of the brass ring (6) which keep the firing pin housing suspended as long as the force of the four balls in the groove (centrifugal force) is greater than the force of the spring (7). If no target is hit , the speed and rotation will decreaseup to a point where the spring forces the balls back into the firing pin housing , driving the firing pin into the firing cap, exploding the detonator (11)
If a target is hit, the desceleration will throw the firing pin housing (4) forward untill the armour is pierced and the desceleration stops. After piercing the armour -when the speed is constant-, the firing pin spring (7) will push the firing pin into the firing cap, exploding the firing cap and the detonator. The projectile will detonate after passing the armour.
With regards DJH
Attachments
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Chris 42 RQ
Well-Known Member
Wrong designation !
Ok So I got the designation wrong !
"KCB" and not "KCA" but I am fairly certain that I have the right case here-
The sharper angled neck is clearly evident when compared with a standard 30 MM Rarden case !
And Dave a very nice cutaway !
Chris :tinysmile_shy_t:
Ok So I got the designation wrong !
"KCB" and not "KCA" but I am fairly certain that I have the right case here-
The sharper angled neck is clearly evident when compared with a standard 30 MM Rarden case !
And Dave a very nice cutaway !
Chris :tinysmile_shy_t:
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pzgr40
Well-Known Member
Hi Chris, doen't matter. That's what a forum is for. Most often I get it wrong too.:sad:
yesterday I received a E mail explaining the designations to me:
35x228 patronen; en wel resp. de uitvoeringen met
-The first letter K means kanone (gun)
-the second letter stands for the diameter: 'B' = 25mm, 'C' = 30mm, 'D' = 35mm.
-The third letter points out if there is a groove for the ammo belt (A) or if this feature is missing and the catridges are clip fed (B)
So KDA stand for the 35mm belt fed gun, KDB stand for the (7 in a clip) cartridges for the clip fed 35mm gun.
Regards DJH
Ps: "And Dave a very nice cutaway !"
absolutely, but mine now.........:tinysmile_twink_t:
yesterday I received a E mail explaining the designations to me:
35x228 patronen; en wel resp. de uitvoeringen met
-The first letter K means kanone (gun)
-the second letter stands for the diameter: 'B' = 25mm, 'C' = 30mm, 'D' = 35mm.
-The third letter points out if there is a groove for the ammo belt (A) or if this feature is missing and the catridges are clip fed (B)
So KDA stand for the 35mm belt fed gun, KDB stand for the (7 in a clip) cartridges for the clip fed 35mm gun.
Regards DJH
Ps: "And Dave a very nice cutaway !"
absolutely, but mine now.........:tinysmile_twink_t:
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Chris 42 RQ
Well-Known Member
Nice explanation !
Many thanks Pzgr 40 for a clear explanation of the workings and designations of the system, a very informative piece.
Now I have learnt something new.
Chris :tinysmile_shy_t:
Many thanks Pzgr 40 for a clear explanation of the workings and designations of the system, a very informative piece.
Now I have learnt something new.
Chris :tinysmile_shy_t:
