Do you think burnt powder/primer resudue built up inside a case after several reloadings will effect pressure(higher) compared to new brass with the same load?

I think it'such a thin film it would be pretty much meaningless in the scheme of things??

While my instinct says maybe, my gut says yeah... Some smart SOB with real world knowledge is going to shoot me down as usual. Till then I'll stick with the original Newton and remember that two objects cannot occupy the same space at the same time. (Unless of course they are Siamese!

If indeed there is a change I would expect it to be very minor, and obviousily related to the change in volume of the case.

What evidence do you have that the burnt powder residue "builds up?" Or are you refering to black powder? If it builds up, wouldn't it be measureable, as in weigh more? I reserve my answer until I have proof of a build up!

I'll give you a hint, if it does build up,(get thicker), then of course it will increase pressure!