I took the spelling of that word from Jeff Cooper's Commentaries, and in the translation I mispelled it. The proper spelling on the eastern side of the Atlantic is Shottist. My cite is here, from Coopers Commentaries. You have to scroll down to find it, but the applicable paragraph is here.
I have been somewhat amused at the spate of indignation I have aroused by insisting that the proper word is "shottist" rather than "shootist". Several people have leafed through a series of dictionaries to tell me that I am wrong about this. Apparently it is a matter of English-English versus American-English. I have been presented on two occasions to audiences in Great Britain and in South Africa as a shottist, and I assume that a proper English language dictionary would support me in this. Our British cousins spell color with a "u" and refer to a fender as a wing. Other examples will occur to you. Personally I prefer shottist, but it appears that I cannot insist upon that.Either way, I am wrong to spell it shotist.
I was always taught that a shootist was a person who made his living firing guns, as in a gunfighter of Old West lore. Conversely, I was taught that a Shottist is a person who enjoys firing and caring for weapons, primarily as a hobbyist. It may be that one is a current usage and one is an archaic variety, but I will defer to my betters. Jeff Cooper is certainly in that category, as is Junior, who is a shootist of rare experience.
I would personally prefer to be known as a shottist, but if the other spelling is customary on this side of the Atlantic, I will bow to it.