Ammunition - could make a version for our bog-standard Gauss rifles, and a heavier version/shotgun version for the Brisant (if it even gets approved). And no, it would hinder the acceleration by virtue of mass - the only time more mass is a good thing is when it's mass hitting the target. Otherwise, it's wasted energy. And if you know a good physics forum, go right on ahead.
Brisant is the name of that grenade launcher, right?
((See, that's what happens when weapons get non-descriptive names!))
Also, I'm not following your logic, but I think I might see why. The sabot, in your idea, is it discarded after launch or not? Because if it is, then it doesn't matter how much heavier it is after the shell has been shedded, does it?
Say you have three shells (=the outer shell, not the full projectile), one lightweight non ferromagnetic (eg plastic), one heavier non ferromagnetic, and one heavier ferromagnetic. The second one obviously loses out to the first one, because it is heavier and doesn't add anything. It's also inferior to the third one, because there the core payload gains extra speed due to a higher acceleration (due to the ferromagnetic shell also being pushed away by the applied magnetic field). Even without an uranium core, the third one would still be able to be fired from the gauss gun.
So now, is it now possible that the loss in velocity from the extra weight is offset by the extra velocity gained from the extra push from the ferromagnetic shell? Or is there some reason as to why the ferromagnetic shell would not add a (significant) increase in speed to the projectile? Hell, imagine for a second we made the shell out of a ridiculously expensive material that gains maximal possible thrust for the same 'amount of magnetic field' (tesla). Would that still slow down rather than speed up the core?
If there is some reason that there would be no speed increase (eg there is an upper attainable speed limit somehow, and if the uranium core can achieve that on its own, the shell cannot make it faster, thus warranting a shell that's as light as possible) then I could agree, but I con't know of any reasonable reason for such a limit.
If you want it not to lose it's shell, that's a slightly different story (though again, if it adds more sped than it takes away it should still help) but then I'd wonder why you'd want that, seeing as how there's good reasons for going for a smaller diameter projectile (better sectional density for one, I think).
We have suits with radiation shielding. Most of them do not.
Ah yes, the magical radiation shielding material. Hmm, it might work, but still, we'd have to assess if the increased difficulty in handling is worth the added damage potential (after all, in the military, they often use things that are reliable, safe and easy to use, not just the most powerful).
It's not nearly as funky (though it is a lot more funky visually), but have you ever seen an example of fluorescence thermochromism? Temperatures changing properties is always cool, even if sometimes it's not so extreme.
Youtube is our friend.
Nothing earthshaking, but interesting nonetheless.
Brisance: the shattering capability of a high explosive. French Brisant - Breaking (Brisance derived from verb form - briser). German Brisant - Explosive. Yes, it's the (actually fairly descriptive) name of the grenade launcher.
Sabots are by definition discarded after launch. And it does matter because while the sabot is attached (within the barrel), it is extra mass to accelerate. Acceleration equals force divided by mass, it's Newton's second law. Add more mass, and to get the same acceleration, you must use more force. And I'm not sure whether the presence of additional magnetic mass will affect the force on the projectile - it's not like adding on a booster, more like spreading out the force (remember, the force is static, generated by the weapon's coils).
Also, I was wrong about using enriched uranium - it's just as radioactive as depleted (both emit alpha particles (which will fuck things up quite badly, if they get in contact with them. They normally don't) at around the same energy). The only way it would be better is if you somehow introduced free neutrons.
That was the exact video I was thinking of.
Don't forget that pure uranium isn't magnetic enough, so you have to add lighter arsenic, and are still something like 9% less magnetic than iron.
I can't find the density of uranium arsenide, but I suspect that it will still be denser than iron (uranium is seriously dense). And the 9% difference is not enough to severely affect the properties of the projectile , I don't think (might be wrong - it will be slightly slower than one of pure iron because of it, but no idea how much, and the increased mass should more than compensate).
And there are better materials available than iron. For example, a quick googling tells me that neodymium (also known as NdFeB, NIB or Neo magnet) is a very powerful one.
Neodymium magnets are of comparable density to iron, and you would probably have issues getting them to launch at all, since they'd probably be stuck to a part of the weapon (I have some - those things are insanely strong) - there's a reason we don't use magnetized iron, though firing it does leave it magnetized. And, of course, still have the issue that the force imparted on the projectile is static.
Don't forget about blackshot.
What is blackshot, again? I mean, specifically, I know what it is in general.