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shift8

75mm M72 AP

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This is just a curiosity I am hoping someone here can answer. 

 

So in all the combat mission games the Sherman 75mm can penetrate the 80mm hull on the Pz4 from 400-600m fairly reliably. I have no problem with this whatsoever. 

 

What I am curious about is the relationship between the M61, M61A1, and M72 rounds. In the data from hunnicutts book, the M72 seems to do better vs RHA, but in the British tests shown in WO 185/175, the M61 out of the M3 does better than the 72 vs RHA. 

Now, several websites I have seen claim the M61 is capable of the 3.7inches of penetration or 94mm vs RHA, and that seems to be very much in agreement with the 92mm often seen quoted for penetration at normal in other places. However, I saw a photo of a book recently on some forum showing 81mm at 0 for the M61 and the 92mm for the 72 at 0. 

 

Basically, what I want to know is this: is the 92-94mm at normal for the M72 or M61? In addition, was the M72 still being used in 1944 in NW Europe? I have searched all over and have found scant evidence for this. The best thing I have found so far is one picture of a M72 being held by a crew in italy in 1944. 

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M72
@ 100 meters, 0°
RHA: 109mm
FHA:  91mm
 
@ 1000 meters, 0°
RHA: 76mm
FHA: 58mm
 
M61A1
@ 100 meters, 0°
RHA: 88mm
FHA: 102mm
 
@ 1000 meters, 0°
RHA: 73mm
FHA: 86mm

 

Source: WWII Ballistics - Armor and Gunnery
 


In addition, was the M72 still being used in 1944 in NW Europe?

 

From what I have read it was only used as a training round by '44 but there were probably exceptions.
 

Edited by Vanir Ausf B

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What is the sources on M72 not being used in 44? So far all I can find on the internet is heresay on other forums but no sources.  

 

Also, if M72 wasnt being used, then why does just about everyone agree the performance on the 75mm gun? Regarding the Pz4 Front or Tiger side, every combat mission allows for penetrations around 500m, as well as many other games etc. It appears to me as though only M72 would do the job.

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Slightly on topic question; but isn't the 80mm of the Ausf. H variant of rather shoddy construction? I always assumed it didn't properly gel until the J, and that the earlier variants - such as the G- was in fact only applique. 

Edited by Rinaldi

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Remember, too, that the BRitish removed the explosive filler. They added concrete (mortar?) instead. More mass meant higher accuracy and better penetration. 

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What is the sources on M72 not being used in 44? So far all I can find on the internet is heresay on other forums but no sources.

I don't remember where I read that and don't have time at the moment to search for it. As I said, there could have been some usage in 1944 but it would have been rare. M61 was a replacement for M72 so it's unlikely M72 was still being issued.

 

Also, if M72 wasnt being used, then why does just about everyone agree the performance on the 75mm gun? Regarding the Pz4 Front or Tiger side, every combat mission allows for penetrations around 500m, as well as many other games etc. It appears to me as though only M72 would do the job.

 

M61A1 penetration of RHA at 500 meters is 81mm.

 

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M61A1 penetration of RHA at 500 meters is 81mm.

 

 

Bonus question: If it can penetrate 81mm, and the armour is in fact 80mm, does that mean that the effect behind the armour will be tiny, as the round only just made it through?

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I wouldn't call it tiny, but it will tend to be less impressive than with a round that massively overpenetrates, and you are more likely to see partial penetrations than full penetrations. However, the M61 (US version, not the UK one) is APHE so it is not entirely reliant on kinetic energy for its after-armor effects.

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...and the displaced armor has to go SOMEWHERE. That's usually in the direction the shell was travelling. Spalling, and ricochets, would've been significant.

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I don't remember where I read that and don't have time at the moment to search for it. As I said, there could have been some usage in 1944 but it would have been rare. M61 was a replacement for M72 so it's unlikely M72 was still being issued.

 

 

M61A1 penetration of RHA at 500 meters is 81mm.

 

Sorry but that doesn't solve the issue. 81mm would make penetration of the Superstructure on the Pz4 or Side Superstructure on the Tiger extremely difficult. Any round impacting at a angle of greater than 9 degrees offset wouldnt make it though, and thats not accounting for the fact that no two rounds go down range exactly the same, hence the penetration tables being averages of penetration within certain criteria. If 81mm was enough, then we'd be seeing Sherman 76mm's KOing Tigers from 1200m with straight shots....and we dont see that in game....or from historical reference FTM. 

 

WO185/175 claimed 94mm of penetration for the M-61 round and 88mm for the M-72 at 500m, granting alot more room for error especially with a little obliquity. Perhaps the penetration tests the Americans conducted were on the low side?

 

Then again, the same rounds tested by the Americans in the M2 gun had precisely the same relationship between them regarding penetration. M-72 being better vs RHA.

 

I cannot find any evidence from a source that isn't random chatter on a forum that M72 AP fell out of use, and I have found at least on picture of a Sherman crewman in September of 1944 carrying the M-72 round. If you don't have time to look for the source then that is your prerogative, but until I see something substantial I see no reason to assume M-72 AP wasn't being used in large numbers right along side M-61 and M-61A1 right up to the end of the war. It would seem silly to get rid of a round that was completely superior to the M-61 against the most common type of armor found on German tanks.  Since M72 AP could penetration 92mm of RHA at 500m, and 84mm at 750m, this seems much more in line with the performance of the gun in ALL of the CM games. 

 

Either that or the M-61 historically penetrated alot more armor than the official American testing claimed. WO 185/175 being evidence for that. 

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The American Arsenal has the M3 gun with the M61 APC round with the following penetrations at 20 degrees:

 

Homog Plate:

500 yds - 2.9 in or 73.66mm

1000 yds - 2.6 in or 66.04mm

 

Face Hard Plate:

500 yds - 3.4 in or 86.36mm

1000 yds - 3.1 in or 78.74mm

 

No mention of the M61A1 or the M72 round.

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M-61A1 penetrates the same. M72 does better vs RHA. 

 

M72 could penetrate 92mm at normal and could be able to make it through 80mm at 24 degrees. 

 

M61 would make it though 80mm RHA at 9 degrees. 

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