I travel rather extensively and have done so most of my adult life. I have always carried, as most of the place I have been require such security as simple common sense. There have been various pistols and on occasion a long gun in a Bullpup form. There has always been a shotgun. In the last several years that has been a Remington 870 in a Bullpup Unlimited, Inc. stock.
I use several different loads. The DDuplex Hexolite 32 and Monolite 32 as heavy slug loads. As defensive or offensive CQ I prefer #1 buck (.30 caliber) max loads, for something a bit more close hand loaded RJL’s are very effective, I use #1 buck, replacing the “00” buck of the original (more pellets), BB’s are fine however BB sized ball bearing are much more effective. The other load I like is the Buck an Ball loading by Centurian. The are all effective man stoppers as well as dangerous game loads when needed. The RJL’s are very effective within the 10 meter engagement envelope. If used correctly in loosely grouped targets, hits on multiple targets is quite possible.
Very loud and effective! Much louder and deeper sound than the light Fiocci smokeless powder blanks. Powerful enough to cycle a semi-auto, but don't use it in one. I did. If you are lucky, you may get three or four shots before it jams up. Extremely dirty, even after just one shot! Use a single shot or double barrel. I spent at least a couple of hours cleaning my shotgun, firing it, then recleaning it again. ;-) I think it is finally reliable again for regular loads to cycle.