Changing Gun Dynamics throughout day

So I've noticed this, frequently. But today was final one before I decided to post.

So throughout the day, and day to day, the "gun that works" seems to change.

For example, earlier today I was absolutely melting people with the CAR hipfire. Melting. 

One magazine and they'd be gone and I'd outlast the tradeoff.

Several hours later, it is not working. I'm emptying whole car magazines into people same distance same scenarior, and it's leaving them with significant health. And ultimately I am being killed.

Why is this happening? Are gun dynamics changing throughout the day? Or are players who use some kind if cheats logging on at a certain time.

But I've noticed the guns that "work" change. Throughout a day. And day by day.

Anyone else?