The question more often seems to have been what is practical and meets best the needs than what is technologically superior to enemy equipment. Argument given before - you don't need to have best equipment if you just make sure it's not the worst, or it's adequate for the purpose - is a very good one. Neither allies nor russians thought that the best results could be achieved with going upspeed fielding of technologically most advanced tank designs available, and that seemed to be the right way. At certain points there was real need for upgraded designs (this is well evident in eastern front) but towards the war's end allies/russians had no absolute need to field the best designs they had in numbers. I see the decision to concentrate fully on M4-series as the right one, even with all it's evidental faults.

the M4 Shermans were fine once an effective turret installation for the 17pdr gun was developed..

of course king tiger due to 2km penerate 180mm armour ...... far destory m-29 before reaching him ... until m47 can compare with king tiger.......

"of course king tiger due to 2km penerate 180mm armour ...... far destory m-29 before reaching him ... until m47 can compare with king tiger" Penetration Data for the 88mm Kw.K.43 L / 71 PzGr.39 / 43 ( Armor Piercing Capped Ballistic Cap ) Weight Velocity 100m 500m 1000m 1500m 2000m 10.2 kg 1000 m/s 202mm 185mm 165mm 148mm 132mm PzGr.40 / 43 ( Armor Piercing Composite Rigid ) Weight Velocity 100m 500m 1000m 1500m 2000m 7.3 kg 1130 m/s 237mm 217mm 193mm 170mm 152mm

I read somewhere that one of the reasons for selecting the M-4 over a heavier tank like the M-6 was shipping. You could ship two Shermans over to Europe int he space required for a single heavier tank.

That was a big part of it but there is another part of the story. For whatever reason, the U.S. remained convinced that the Tiger, King Tiger and Panther were rare tanks and would be rare tanks when they invaded France on D-day. They received quite a shock when these tanks were anything but rare. Things could have been much different had somebody had the forethought to realize that a heavy tank should have been pursued and battle tested early on. instead it took the shock received at D-day to spur the development and then the surprise at the Battle of the Bulge to convince them to get a heavy tank into operation. Thus the M26 came on to the scene as an MBT type tank to be battle tested. The M26 while a good tank was not a great tank because the idiots at the armor board did not see fit to explore the benefits of a few big tanks like the M6 to be an integral part of each armored brigade. What would have happened had they decided to have armored brigades made up of a couple of M6s, some M3's and a bunch of M4s? The problems here are very complex. See, they also did not want tank drives running off to do battle with tanks. Tanks were there for support of the infantry. So tank destroyers were used. The idea was to flank the enemy with fast/light tank destroyers. Here again, the U.S. was mistaken in believing that like they did in Africa, that the vast majority of tanks they faced would be Pz4s and Pz3s. They simply did not expect there to be so many Panthers, Tigers and King Tigers. Had they known this, I think they would have wanted an upgraded version of the M6 to call on. Imagine what this tank could have been like with twice the armor it had and the 90mm, 17pdr or the 3.7" as a main gun. They could have even kept the 37mm coax to deal with light armored targets like Pz3s and Pz4s. It would have handled these tanks better with APDS ammo for that gun. The benefit is that the smaller rounds to deal with smaller tanks gives you more rounds to shoot as the bigger the round, the less you can carry.

Generally this argument overfocuses on M4 Shermans vs Tigers, or Panthers. The majority of Shermans were destroyed by AT guns, panzerfausts, MkIV tanks, and a variety of tanks destroyers and assualt guns. Just about every German AT weapon fielded after 1942 could deal with the Sherman. Some better than others, but the armor of the Sherman was becoming obsolete, as was its original gun. Aside from the M6 there was an entire series of test models, T20, T22, T23, T25 which could have been placed in production in 1943. In fact some 250 T25 were built during late 1943. All these had the same hull/chassis layout as the T26 (M26 Pershing). All had a significantly lower profile than the Sherman, Panther, or Tiger. And the frontal hull armor was better sloped than the M4, the M6, and the Tiger I. The main difference between the these different models was thickness of the frontal armor and the transmission. Some were manual, some automatic, and some had a electric drive. The problem was not "idiots in the US Army Ordinance Dept". They produced many good tank designs. None perfect, just many good ones, including the M4 Sherman. The problem lay in HQ US Army Ground Forces. Specificly in General McNair who commanded AGF until he was killed in 1944. He had direct responsibility for equiping and training all ground forces before handing them over to Eisenhower, MacAurther ect... The decision to stick with the M4 as the only MBT for shipment overseas was primarily his. Other field commanders often concurred with this. In January of 1944 Patton offcially stated a heavier tank was not needed, and that the M4 would be the superior tank for his use. Many other US tank commaders agreed when polled that month. There were dissenters. Gen Devers, who proceeded Eisenhower as commader of US forces in England, read the intellgence reports on German tanks differently. He sent several messages to the Ordinance Dept, AGF, and Gen Marshall demanding heavy tank battalions for the invasion of Europe. McNair firmly refused. On establishing SHAEF Eisenhower revisted the question by convening a 'armor confrence' in Jan 1944. He went with the recomendation of Patton & the other prominent armor commanders attending.

Also, the doctrine for US armor forces was that tank destroyer units were supposed to engage enemy armor. The main weapon on the M4 was supposed to be the machine guns.....which they would use once they broke into the enemy rear area. And shipping space was a big deciding factor.

It wasn't just US doctrine, the Brits and Canadians also bought in to the argument that tank destroyers and AT guns destroy tanks, tanks were used for exploitation. Tanks were not used to kill tanks. An interesting concept, that was extremely flawed, and resulted in many deaths in Allied Armour units. One other aside; the T5E1 L/65 had absolutely zero in common with the L7, with the exception, of course, of calibre. The L7 was, essentially, a product improved 17 pounder. As a matter of fact, the breech and breech ring are interchangeable between the 20 pounder and the 105!.

I realized your point..just didn't make it since it was about Tiger v T-29...but your are spot on. Not to knock the tank killer units.....they were filled with incredibly brave men who did some amazing things, but it was a failed doctrine. The US Army based this on some faulty observations based on the Louisiana Maneuvers of 1940.