TJ,
Well I think we have narrowed your problem down real quick. More than likely it is you modifying your ammo, making the hollow point larger.
I know many folks have done this over the years and for what reason I will never know. Please let me explain.
First, killing any animal is simply about shot placement. I do not care how big a hollow point is or how fast a bullet is running, you have to have proper bullet placement for a clean swift kill.
Secondly, a larger hollow point will not kill any quicker than a standard hollow point. It is not the size or shape of the bullet, it is shot placement.
Third, modifying a bullet will make a difference in how a bullet or round groups. You are taking a uniformity bullet and now making a bullet non-uniformed. Remember the bullets are made off or out of high cost machinery so they come out uniformed. Is each bullet 100 percent perfect? Absolutely not, but they will be closer to anything done or made by hand.
In closing, don't modify bullets. You are only wasting your time.
Just my opinion.nothing personal.
Take care and good luck shooting.
KW, Cardinal Fan