AGM M4 GBB Overhopping?
 

Yeah, my AGM M4 is overhopping on .25 Tamshi BBs. I know that the AGM M4 shots at a high fps so does that mean there is a faster backspin on the bb contributing to the overhop? Should I just buy a bag of .30 and see if that solves the issue? Could the inner barrel be bent? The stock AGM hop up rubber ripped and it was overhopping before the bucking ripped, so I replaced it with the G&P hop up rubber, and its still overhopping. Should I remove the bucking to see if it shoots straight?

Do not do anything to the hop up until you lower the FPS of the gun. The reason why it's overhopping is because the fps is too high. If you're using stock or upgraded hop up rubbers they'll still get torn apart because the bb is making contact with the rubber with too much force.

This leaves you with 2 options:
1. Lower fps aka swap the spring with an m90.
2. Tweak the hop up to make minimal contact so that it isn't making an immense parabola.

#1 is favoured over #2 because it not only prolongs the life of your hop up rubber but also your gearbox (slightly).
#2 is more of a trial and error situation because evidently if you reduce the amount of surface area exposed to the BB you reduce the damage inflicted, but you're still left with a hop up that degrades quicker over time and can result in over hopping.

What is the current FPS rating on the gun w/ .20 grams (if you have them, they are standard) or .25 grams WITHOUT hop-up?

This is a GBBR, .25 bbs and it overhops on the lowest setting. The AGM M4 GBBR has the tendency to hit 450fps stock on a .2, so I am thinking that may be the problem. I am not certain about the fps.

It's a GBBR, it doesn't matter what it shoots on .20s
The only thing that really matters is your muzzle energy on the BB weight you're currently shooting

Try it with .30s, maybe your hop arm is messed up? Is it using anything for a nub?

Oh woops.

Don't know much about that then... perhaps try installing an RA tech NPAS to control the FPS? Because 450 is a bit hot for some fields.