Rick, I think you take some of what I have written a little out of context. I didn't say about tin and land engrave widening what you evidently think I said, please review that thread again for the specifics. Based on what you've written, I'm pretty sure you never would have experienced what I was pointing out......therefore you have no frame of reference to discuss it and very little of what you've experienced below 2K fps applies. Basically you and I are talking about two completely different kinds of shooting, and you haven't found out yet just how much the "rules" you've learned change when you really start to push the velocity envelope. And you know what? You might start working on HV rifle and STILL disagree with me and get great results with a different alloy, I doubt it, but it could happen. Just because I have failures with richer alloys at HV doesn't mean everyone will.
As far as the extra tin exacerbating the problem of little bits of stray bullet alloy sticking here and there (not meaning bullets sticking in the cavity, but lead bits and smears sticking to the blocks or sprue plate) I've found that it does. Lower tin content, easier the stuff flakes off the blocks, sometimes the deposits will just flake off with a fingernail when cool. With just 2% additional tin, it often takes the eraser method to remove it. Alloys with more tin, harder to remove. My mileage. If there's a little gap between the blocks, added tin makes the alloy more likely to flow into them, same way it helps make sharp edges on the bullets. A really hot mould also encourages that effect, regardless of tin content. I have a couple of old worn moulds that need to be run hot but with a very cool alloy with not much tin...or they get little fins where the edges of the cavities are rounded off. If you don't have this problem it's probably because you have good moulds and know what you are doing (no surprise there).
Tin is good, bad, or indifferent, it just depends on who you are and what you're trying to do. I never said tin was "evil", but when employing proper casting techniques I find it largely un-necessary to add more tin than clip-on wheel weights normally have already unless you're trying to make a certain alloy do a certain thing or are needing to add some girth to the bullet. Saying that doesn't make me "wrong", but the wholesale advice to throw 2% bar tin at everything is not necessarily "right" all the time, either, as it took me over 25 years to discover. Like you wrote, people indeed need all the info and figure out what they need for themselves.