Would prosecutors use your reloads against you in court? If they knew enough about ammunition, they might. But prosecutors are usually up to their necks in cases, and must prove guilt to the jury beyond reasonable doubt. And if their case gets reversed on appeal, their reputation is damaged, but not their income. They get paid anyway, until they lose a few cases too many, or their political party gets voted out of office.
The biggest problem would be in civil law suits, which often follow criminal case dismissals. "Beyond reasonable doubt" no longer applies. The plaintiff's attorney most likely would take the case on contingency -- he/she gets a cut of the loot with a win, nothing with a loss. A plaintiff's attorney will grasp at anything useful, and use it to whack you about the head and shoulders in front of the jury. That's his/her job, his/her meal ticket.
Massad Ayoob has said it: don't use "cop killer ammo" (i.e., reloads) for self defense. I would add that there is so much good factory ammo out there, I don't see how you could improve upon it with your reloads.
I'm not an attorney, but I once dreamed I was. Woke up in a cold sweat!
Cordially, Jack