Bare Gel Tests vs. Gelatin + Denim

[358156hp]

I'm hoping this will be a simple question, but the subject has always somehow bothered me a bit. We see all sorts of Gelatin tests on Youtube, and some even appear to be relevant and valid, but are gel tests without denim, or other barriers even valid? There are a lot of videos shot either way, or even both ways, and except for uniform comparison the non-barrier tests strike me as unrealistic, especially in light of the effect denim and other light barriers have on bullet performance. A great example is SIGs 124 gr 9mm bullet which expands well in bare gelatin, but plugs up and falls on its face with denim. So, how valid are bare gelatin tests?

[PNWTO]

So, how valid are bare gelatin tests?

That really depends on the people behind the testing and the variable(s) that go into the mediums used. I don't really watch YouTube ammo tests that often but when I do I'm usually paying more attention to the chrono than the projectile. They are insightful and it is neat to see penetration and retention and whatnot but for anything I truly care about I look for answers in Doc's contributions here and/or some of the LEOs here if we are talking wheelguns.