Sherman 75 tank gun

Why didn't the army develop and manufacture special ap rounds for the 75mm tank gun. They had apds for the 57 and hvap for thr 76 and 90. I know production was switching to the 76 but we had thousands of 75s in service. Ammunition like hvap would have greatly improved the Sherman's ability to challenge the panther and tiger. So why didn't they make better ammunition. Was it because they already saw the 75 as obsolete and to be replaced by newer better guns

 

It's complicated enough a subject that I devote most of a chapter to the development of AP projectiles and so on in For Purpose of Service Test. The initial AP rounds developed by Ordnance for the US Army were simple AP - solid blocks of machined steel. The first "special" AP round developed was the APC, which was the designation for a AP round with a HE charge and a ballistic and a penetrating cap. They also began work on improved APDS penetrators (actually designated by US Army ordnance as High Velocity Armor Piercing-Discarding Sabot or HVAP-DS), but without success - all the APDS used by the US Army for the 57mm AT gun was British-produced. At the same time, the 76mm gun was developed as a replacement for the 75mm gun, although there was some resistance by the Armored Force to wholesale replacement of the 75mm, since its HE capability was preferred over the 76mm. Then, when the Army experienced the shock of encountering the Panther in large numbers in France, the inadequacies of the 75mm and 76mm APC shortcomings were exposed (the HE cavity weakened the shell body and worse, poor fuze action resulted in prematures before penetration was complete, resulting in shattering of the projectile). That led to the emergency development of APCR (usually called HVAP, but actually designated by Ordnance as HVAP-CR as opposed to the failed HVAP-DS) in the summer of 1944. Since it was considered a simpler design than an APDS, no development had been done on it before, but it was completed and initial quantities were in the field in about six weeks. However, by that time, the Armored Force had finally lost interest in the 75mm, realizing finally the better penetrator was needed, so no HVAP was developed for it.

 

From what I've read, it seems that just about every discarding sabot high or hyper velocity AT round suffered from accuracy problems. Getting the sabot petals to come off at exactly the same time/same way was problematic. The Germans got around this by keeping the penetrator inside a regular diameter shell surrounded by a light (aluminum?) filler.

The other consideration was that all these penetrators were made out of carbide-tungsten (tool steel, steel to cut steel) which was hard to manufacture and needed to make weapons. Therefore, in each country the amount allocated for AP projectiles was quite small. Therefore, the amount of such ammo was quite small-even in the U.S. Army.

 

Countries entered WWII with dedicated armor doctrines based partly on what they thought would work and what technology was available to them, that being said Germany probably had the most evolved doctrine at the beginning of the war based on crew training, unit organization and tank design. While effective, it was not perfect. Germany relied on 3 types for 'exploitation/capture' missions (Pz III, Pz 35t/Pz38t) and Stug III for fire support for the infantry and Pz IV to provide the same for the panzer formations.

The rub was the exploitation tank were not always powerful enough to destroy the 'heavy' Allied/ Soviet armor and the support tanks
were in more limited number, sometimes no more than a dozen per division. Worse the multiplicity of types. complicated logistics.

For the US with two vast oceans to help defend it much of the pre-war budget went to the navy, leaving limited amounts for tank development. The US looked at Poland, France and early North Africa fighting and drew conclusions based upon what they saw and were told by their potential allies and what technology was available to them.

The US had a superior 75 mm gun to the German low velocity gun then in widespread use and saw the opportunity to combine both the exploitation mission with the support mission in a single vehicle, the M 4 Sherman. This eased logistics for a country that needed to arm itself and allies, and get those arms across the globe in great numbers and with plenty of spare part to keep running. The US also had a decent high velocity gun (3 inch-76 mm) but it was too heavy/bulky to fit a Sherman, but could be worked into a Tank Destroyer by giving up armor for room/speed.

So US doctrine called for platoons/companies of standard M 4's to deal with small numbers a panzers and when larger numbers were encountered Tank Destroyers, anti-tank guns working with massed artillery and maybe air support would be called in to work with standard Sherman's. With the allies going from victory to victory this seemed to work, allowing the US to design a 76mm gun/shell that would fit a Sherman.

In the late spring of 1944 such vehicles began to arrive in England in some numbers, but not enough to fully transition and since it used a different shell offered logistic complications. Then the wads the need to retrain US tankers on how to properly use it just before D-Day. US
commanders saw this as dangerous and so held these in reserve.

Then came Normandy and encounters with larger numbers of Tiger/Panther's, especially once beyond the range of naval gunfire support. This led to the introduction of 76mm armed Sherman's, usually one per platoon like the British did with their Fireflies. While this didn't take away the concern of US tankers of going against larger German tanks the allies continued to go from victory to victory and had a better overall chance of surviving than the German tanker who had to also face massed artillery and ir strikes while keeping a ever dwindling number of powerful but overly complex tanks in the field..

 

Yes I found it interesting that many tankers who fought in North Africa stayed with their 75 Sherman rather than upgrade to the 76. The 75 gun tanks were more for support the 75 being very effective with its he round the British I read loved it for that reason too. Even bored out and rechamber many 6pdr for 75 ammunition. I'm surprised the could bore it out that much and the gun still strong enough for that. Don't know why they didn't just ask us for 75s we gave them thousands of other guns and equipment. It was specifically to use the very effective he round. They said the most things tanks encountered were not other tanks but anti tank guns more tanks were knocked out by atg than by tanks. But firing at a small target was a problem the British guns had a very small he round and not as effective as the US 75 the British loved it as it had Google range and a very good anti personal effect. Pattons third army had amazing effect with the 75 gun Sherman's knocking out far more enemy than loses due to great coordination and tactics that they felt they had learned the hard way from their days in North Africa. I have to admit it was amazing how many time they had whittled down Rommel and reinforcements would arrive to save the day. Should we have done more with heat or hesh rounds. Didn't the British do some development on hesh rounds and the US and the U.K. doing experiments on heat based on captured German weapons.

 

Haven't you also posted before that the issue with the American tank guns was the type of propellant, shell, and firing action as the size of the gun really didn't make a difference? Did we ever address that issue during the war or realize that was an issue more than the size of the gun?

 

Don't believe so I'm not familiar with what different types of propellants were even available, was there many. I do know different propellants had a different burn or flash rate that effected how much propellant gases they could produce within a giving time.

 

That was to Rich

 

Oops my bad

 

The first 200-odd 75mm-armed Churchill tanks were converted in North Africa, using salvaged and spare American 75mm M3 Guns originally in the Grant/Lee and Shermans. They were known as Churchill 75mm NA (for North Africa). Its success led to a huge demand for more such guns, which outstripped the supply of American guns. At the same time, the Ordnance Quick-Fire 75mm Gun was developed after it was discovered that the Vickers-designed 75mm High-Velocity Gun could not be fit into the Churchill turret. It came from the serendipitous realization that the cartridge case of the American 75mm round and the chamber of the 6-pounder gun were nearly a perfect fit. It is often said the barrels were "bored out", which is incorrect, a new 75mm barrel was designed and produced that mated block with the 6-pdr breech.

 

Thanks for the info I always thought it would be simpler to use a new barrel than to bore out one and hope it had enough meat left to retain the pressure. Anyway my buddy and I use to discuss that saying it sounded a little fishy. Again thanks for clearing that up this forum has been very informative. Thanks again for your time and information.

 

Type of propellant was not a problem, all nations used variations on double-base or triple-base "smokeless" powders. Ordnance did resist the use of chemical additives to reduce flash, believing they increased wear. The AFV&W Section ETOUSA did believe Ordnance under-loaded cartridges, which was true, again to reduce wear and because of the safety margins used. However, the evidence is increasing propellant and thus Mv would have reduced performance, given the poor design and manufacture of the APC projectiles.

Poor fuze action also affected things, because a premature, which was common, destroyed the projectile before it achieved penetration.

Some 90mm AP (solid) was manufactured as T33 with improved heat treatment near the end of the war and performed better, but no wartime similar modification was done for 76mm AP. Most damning, there was very little Army-Navy cooperation on AP designs prewar or during the war. The Army apparently gained zero benefit from the interwar testing by the Navy at Dahlgren. After wars end, the Navy tested Army specification 3" AP against Navy 3" AP and found in markedly inferior.

Worse, in April 1943, tests of captured German 7/5cm AP found in far superior and the same for German fuzes. Despite recommendations to copy German designs and manufacturing processes nothing was done.

 

Yeah I don't understand the reluctance to copy the better German technology. Most countries do that today. I read during the Vietnam war they would salvage wrecked mig 21s and others to study and get an idea of the tech level the Russians were at. Said the control actuators exact copies of the phantoms. I never could understand why we didn't copy the panzerphaust it was simple and cheap to make. Also when our bazooka became less effective why didn't we copy the panzershrek it was much more effective and another low cost weapon. The Russians studied the panzerphaust redesigned it and made their RPG which is still a effective weapon. The army is perturbed that their multi million dollar tank can be taken out by a three hundred dollar weapon. Good thing the RPG 59 was in small supply to the Iraqi most of the earlier RPGs had little or no affect but that new one damaged a few and disabled a couple I think one was disabled the unit commander felt it was too dangerous to try to tow it that it would slow down the hole column and followed procedures to strip out all vital eauiptment and threw demolishtion chardes to destroy sensitive technology. The army feels the new tusk II and that new anti missile rocket protection system will defeat the RPG but I haven't heard if it's been filed tested I know their working with Israel on it. I swear I saw something were Israel was claiming and marketing it as their system when I read we designed the initial tech and were funding their help on perfecting it. The Japanese looking for light anti tank weapons studied the Russians RPG and made their own copy modernized to their liking. Wonder how those pop up fins work the tube is so small do they fold into the tube? The Japanese have spent a lot in weapon developement. They learned they lost because they didn't keep up in technology. The us had offered to sell them tanks even the Abrams but they were determined to build their own the t90 to me looks a lot like the lepard two the new t10 is a improved t90 with new power tran and armor layout like the challenger was a chieftain with the new chobram armor. The Japanese rifles have been the taking of features of other western weapon systems and combined to meet their wants and needs the type 89 was the combination of three rifles as well as the newer rifle using the 5,56. Like the F2 is a F16 copy but again built to what they think they need the airframe is slightly larger for a more powerful engine the wings and control surfaces enlarged the Japanese said they feel they will be fighting a defense war and wanted a plane that could carry a large amount of long range missiles for sir combat and a large load of anti ship weapons. I like the look of it I want o get one or covert some of my dml F16 they were cheap when they first came out and looked good three bucks bought three to six of every boxing ang squadrons af squadrons. Israeli want to try to add the new spine for the F16I and the newer US F16. Shouldn't be too hard to add just a spine. Maybe use a few for experiment designs I think one with delta wings and canards from one of my kifirs or F21s. I have an old LS F16XL not bad but dml has better detail was thinking of using the wings on the dml kit. Anyway I must have about two dozen even after selling s bunch. Yeah I was an addict go to the kit shows and buy stuff cheap even if I knew I had lots if it was cheap l bought it. Those were fun days cheap models inexpensive books. Now everything is so expensive. Models I got for five now thirty ouch. Wish I hadn't sold some of my old kits but then I thought my marriage was more important. Some day lol

 

Post-war article by an American tank commander on the M-4 Sherman. He'd take the Sherman and its mobility for offensive warfare over the Germans more defensive minded approach.

http://www.digitalhistoryarchive.co...ttalion_commander_-_tank_versus_tank_1946.pdf