Scott,
Have you ever watched the video of the fellow that did the very project you are talking about. He built his 4 bore from scratch and ended up taking it to Africa for Cape Buffalo. Very interesting project.
Take care,
Dave

Oh my!!! The denial has hit a new HIGH! That barrel is a hair over 24", fish! I suspect that the flash has caused the illusion you are referring to. It is an illusion, you do realize this I hope.

Scott

Scott, do you want to scatter your enemies and drive them before you? Just take another photo of your barrel like the first two, but put a scale of some kind (tape measure, ruler etc.) across the muzzle, just above or below the midline. Be sure to exercise your advanced photography skills to the utmost and make the picture very clear. This will unmistakably show that you have a barrel with a bore diameter of about 1 inch. Glorious victory will be yours, and your secrets will still be safe.

20mm cases are big enough if you don't want a huge rim.

or you can put a rim on( like we did for 12GA FH).

A 1.040(which I think you said your final bore is) bore case using 20 mm brass

would be 1.080 neck and a 1.090 base, with a 1.162 diameter

rim.That is built with my process, with no thinning of the sides above the base...BUT THE SMALL TAPER TO THE SIDES,

AREN"T FOR HAIRY LOADINGS AS THE CASES MAY STICK----

THAT IS WHY I SAY THE BORE SHOULD BE AN INCH---To give the sides a little more taper.Any where between .983 and

1.000 bore.You see if cases don't stick with hairy loads,

using right taper, then you actually have gained power---

much more than the little extra bore gives using black powder or equivalent loads...I never design any case for

less than max loads, whether max loads are used or not.Ed.

"illusion," i do believe, is, indeed, the correct term for the photo in question.