with black powder/bp substitutes being a total explosive it should burn everything you put in it.
Yes, and no. BP is an explosive, but it's blast characteristics are much different than smokeless powder, and thus the pressures generated are considerably different.
take your ml and shorten the barrel 5-6in ,i bet it will shoot faster. only thing slowing the bullet down is friction,less time in the barrel,less friction. short barrel shoots faster.
That is a trait of the different explosive qualities of BP over smokeless powder, and again, the pressures involved are completely different. BP doesn't generate anywhere near the pressures of smokeless powder. This is how and why BP could be and was for centuries fired in barrels that were little more than wrought iron. If you put smokeless in those barrels, they will explode because of the different pressures involved.
The issue at hand is whether the barrel and breechplug in that 700ML was designed to operate with BP pressures (which it was) and whether it can handle the substantially higher, different pressures of smokeless (which it was not designed for).
