I havea coup;e of 8 gauges and after reading this, I was struck byt he dimensions. The chamber seems normal except for the non-taper. The groove diameter is what threw me. I have a combination gun by Sauer which is chamberedfor a 16 ga in the shot barrel and a 20 ga bore cartridge in the rifle barrel. That barrel was made from a 20 gauge barrel rifled to a groove diameter of a 16 gage and chambered for a short 20 ga brass case. A case ID sized ball is used in the 20 gauge load and expands to the 16 gauge sized groove size.
A normal bore sized 8 gauge bullet for a smooth bore would be around .835". (I shoot that size round ball in my Scott single barrel).With the case being .937 straight, I suspect the case ID may be larger than the
normal groove diameter you would get with a noral tapered case. It may take some detective work to find the proper diameter that will obdurate into the bore and be a tight fit in the cartridge. The round balls I shoot fit snugly in a new tapered brass case. You might also have a mold made for a heeled bullet that could be crimped into a tapered case to avoid a paradox type crimp.
If your gun is made for a straight brass case of groove size interior case size, you may need to have some custom cases turned or anneal new cases and fireform them before loading. I presume custom cases would be needed anyway for a pinfire. Never tried to deal with one. I have seen references as to new ones custom made or conversion or standard cases.
