Largest gun that will fit on a tank

So I was looking at our glorious Spacebattles logo and noticed the tank barrel on that image is a lot longer than I remember it being on the T-34-85. Which got me thinking, what's the largest gun

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Largest gun that will fit on a tank

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The Tank Museum - The biggest gun ever fitted. Join

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NationStates • View topic - Largest gun ever proposed to be fitted on one your tanks?

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