In comparing the performance of the model 1840/1841 8-inch seige mortars and those of the 1861 model, I notice an unexplained difference. The range table charge of the old model stops at a mere 1 lb 6 oz. versus 2 lb for the new model. Now, I know that some of the larger mortars occasionally failed, but the 8" was the the smaller of the heavies...and such a small charge gives it no more range than a Coehorn. So I suspect this was not a maximum charge, otherwise there would be little point in having the piece.

What was the maximum charge/range for the older 8-inch siege mortar? Some period manuals that don't distinguish model year indicate 2 lb charge maximum. Is it correct to assume this would yield a similar effect as with the comparable 10" siege mortars? (In those there was several hundred yards range increase at low powder load for the new models, but less than 40 yard increase at full powder charge.)