Ammo could cause issues, but shooting different types of guns can too. If I mix strikers with SAOs with DA/SA with PCCs..I usually don't shoot any of them well.
That is the biggest one for me also.
If I take a revolver and a semi-auto to the range I usually do pretty well, not always, because we all have bad days as has been said above. Some days really bad. Finding out why is very important.
I have found that if I take more than one semi-auto with me in say 9mm, that I end up fighting with myself for trigger control. Then I discovered that starting with the semi-auto that has the heaviest trigger and go to the lightest, really helps a lot in holding my accuracy.
Same with starting with the semi-autos, then going to the revolvers seems to work best for me.
But I have walked out of the range before because I was just wasting ammo, it just wasn't going to happen today.
I have also shot ammo that my gun didn't like and I knew the gun shot better than that and that I was holding on my target correctly. I those cases I don't buy that ammo any more.
"Reloaded" has nothing to do with the accuracy if it's done correctly with components that are known to work well together. It the loads were just thrown together to do as cheaply as possible for profits sake, with a load all powder, you may have a problem with the ammo. I would start there, go back to ammo that you know is accurate, then try more of the cheap stuff to see if it's you, the gun, or the ammo.