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Main Gun Ammo - Revisited


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Apogee? They mean the maximum height of the projectile along its trajectory. AKA the maximum point blank range or maximum direct shot range. So the effective range seems to be based on the round's maximum point blank range on a generic MBT target.

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"apogee" is appropriate - unless the round is being fired elsewhere than on the earth. :D

 

 

I guess that 2.3m is selected as a reasonable "generic MBT" height, as you seem to be suggesting.

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125 3BM22, 105 mm M111 and 105 mm NP105A2.

 

 

https://ibb.co/3mJtbYz

 

Btw. How to paste picture into my post this time without attaching it (which has so low limit)?

 

P.S. "You are not allowed to use that image extension on this community". Mozilla. Maybe I`ll try chrome then.

Edited by Przezdzieblo
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Does anybody has information on Dutch trials held in 1979 between US M-735, British L64 and German/Israeli M-111, apparently resulting in adoption of British 105mm APFSDS ammunition. Has that deal went through?

 

Dutch did use APFSDS, but I have no idea on type. Some sources have even mentioned German DM-23 and even DM-33. It seems they have also used British L52 APDS prior to that.

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about L64

 

 

 

There is an embarrassment in that the muzzle velocity which was quoted at the Bourges trials which demonstrated the superiority of L64 over the US M735 round, and which was subsequently requited in documents, is not now likely to be met. Although we remain confident of the superior performance of L64 the extent to which this point will of itself incline potential buyers, such as Belgians and possibly even the Dutch, to other solutions remains to be seen. 2. Shatter. Further trials of the basic WNC propellant had confirmed evidence of shatter at low temperatures. This was unacceptable to the UK. MGO asked whether we were being stupid as the propellant was used in the FRG 120mm KE round.S/GR2 RADHE said that the OB would not accept the situation. DGW(A) said that we knew that the Germans were having more accuracy problems and shatter could have something to do with that. In some batches the pressure at -40C was higher than it should have been. S/GR2 RARDE said that this propensity to shatter could not be «blended» out. Tests with reduced diameter granules had not improved the situation. 3. MV. Each batch of basic WNC propellant had shown a different temperature coefficient(the original was about 4 but the latest had reached 5.8). As a result RARDE had been forced to specify an MV of 1472m/sec. Competitive rounds were set at about 1465 m/sec whereas we had predicted 1505m/sec from the UK propellant at the IEPG competitive trials. It might be possible to blend out the temperature coefficient variation but that would not solve the shatter problem. 13. It is unlikely that, even if a successful development programme could be carried out in the time stated above, the MV will exceed 1470 m/s. This will give little edge over the Israeli M111 round, the only advantage of L64 being its greater shot development potential (W/Ni/Fe core, reduced drag). However, the ROFs have as yet given no indication that they are seeking to pursue the potential offer by W/Ni/Fe cores. Conclusions 15. The L64 programme has run into serious trouble in the final stages of its development. A difficult decision must be made within a month as to whether it is wise, or indeed possible, to inject further effort to save the project in view of the scarce resources available at RARDE, PERME and DPEE. THE ROF/SALES DILEMA 8. L64 development is already late. Performance has fallen below that demonstrated at Bourges in 1978 when 1505 m/s mv was announced. (Difficulties with temperature correction for chamber pressure have led to the 1471 m/s figure). Competition from the Israeli M111 round now being manufactured by Diehl in Germany is intense, this round being available in production quantities at very competitive price.

 

 

RARDE and ROF Birtley are confident that the cause of the core failure has now been identified. The previously planned investigation has now been completed and has cleared both the quality of the components and the overall strength of design, and had shown that the assembly of the projectile to the filled cartridge case is the critical factor. The core failure is considered to have been caused by compaction and assymetry of propellant caused by shouting up using unapproved methods Technically the remedy is simple and there is sufficient time in the programme, due to other slippages, to overcome the problem and prove confidence in the solution. The three tonne of Lot 727 was handsorted to remove short granule length propellant, but this was not possible with the 19 tonne lot as there was insufficient labour available….

 

i can try find full report on PC, but L64 IIRC never get to any serial use in Europe.

 

as for Dutch army i think they using DM33

 

https://upload.wikimedia.org/wikipedia/commons/f/f4/120mm_Fin_Stabilised_Discarding_Sabot_-_Tracer_FSDS-T_%28left%29_%26_105mm_Armour_Piercing_Fin_Stabilised_Discarding_Sabot_-_Tracer_APFSDS-T.JPG

 

but it's only museum... maybe somebody have photos of rounds inside tanks ?

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NP105A2 projectile seems to be about 540 mm long, thus core circa 440-450 mm long, circa 25-25,5 mm diameter, 17,6 g/cm3 density of 3,7 kg W-Ni-Fe core.

Well... tried arrow's calculator. "Propelling" that rod to 1485 m/s vs 60-degree target 235 BHN gave 460 mm perforation. Assumed quite high velocity drop after 1000 m - 70 m/s. Performance at 2000 m - a bit more than 400 mm. 300 mm still possible between 5500-6000 m. So information about holing 150 mm plate at obliquity of 60 degrees at 5800 m sound plausible. Performance vs NATO single heavy would be lower, because some extra penetration for behind armour effect is needed. British H6/H62, which looks a bit longer than NP105A2 and was fired at tiny higher velocity, could defeat NATO single heavy at 5000 m.

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  • 2 weeks later...

"Effective range" for those types of rounds is not something set in stone, like with missiles or arty rounds. It is a combination of factors like mechanical dispersion of specific round from specific cannon, velocity drop and FCS solution, plus different evaluation methods in different countries (like 50% hit chance on tank sized target or 80% chance)

So that 2000m is not concrete number and one can surely expect to hit targets at much greater ranges.

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Often enough it's a code word for the tracer burnout range.

 

Or, the tracer burn duration is tailored to match the expected upper engagement range limit, to put some causality into the statement.

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Hello,

 

The QF 20 pdr tank gun was developed in 1948. What was the name and dates of introduction for the various ammo it used?

 

I have the following

 

Mk1 APDS 1947

Mk3 APDS 1950

Mk4 APDS 1955

 

unknown APCBC round

unknown HE round

unknown canister round

 

 

Does this look right?

 

 

Thank in advance.

---Kenny

 

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Yeah, it was the same breech with a new barrel. You could interchange them by screwing on a new barrel, which was quite useful in gunnery training because you could use up 20pdr ammunition in training.

 

Reportedly the Canadians in 1962 had converted all their Centurions over to 105mm. Then the Cuban missile crisis sprang up, and they realised they didnt have much 105mm ammunition, and lots of 20pdr ammunition. So they had to convert all the ones in Germany back again to 20pdr over the space of a weekend. I imagined there was a lot of very unamused troopers at the end of it, particularly when they had to convert them back again...

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I think most Centurions in Canada kept 20 pounder (Mk.5), while those in Germany were 105mm (M. 5/2, Mk.6 in 1962 and Mk.11 in 1965). I am even guessing that 20 pounders might have outlived 105mm, as Canadian units in Europe switched to leased Leopards in summer of 1977 while the last Centurions in Canada were withdrawn in 1979.

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I think most Centurions in Canada kept 20 pounder (Mk.5), while those in Germany were 105mm (M. 5/2, Mk.6 in 1962 and Mk.11 in 1965). I am even guessing that 20 pounders might have outlived 105mm, as Canadian units in Europe switched to leased Leopards in summer of 1977 while the last Centurions in Canada were withdrawn in 1979.

 

So it sez here: https://www.canadiansoldiers.com/vehicles/tanks/mainbattletanks.htm

 

It seems upgrading with 105mm guns was done in 1962, so it seems likely only a few were upgraded before reverting to the 20 pounder,

 

By 1971, Canada's Centurions were of the following variants:

 

  • Mark 5 (20-lbr main armament): 241 in service

  • Mark 5/2 (L7 105mm main armament): 6 in service

  • Mark 11 (L7 main armament, uparmouring,infrared sights and lighting, .50 ranging gun): 75

  • Armoured Recovery models: 9 in service

  • Bridge Laying variants: 4 in service

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