So after looking into some things further, i remember now why i pushed the 25-45 out of my mind. It has barely better balistics at 200 yards than my .300 blk with decent hornady or nosler hunting bullets, but with a smaller diamter bullet. They say it is a 300 yard hunting cartridge, but i would say it is 250 yard maximum on deer, based on the ballistic charts i have seen.
Now to me, the difference between my .300 blk and the 25-45 sharps is not enough to make me want to build a new rifle, other than for the reason of you can never have enough guns if you have the money.
The biggest problem i found is i feel likr 25-45 is a handload only round, which is nice that it uses a .223 parent case. But i could not find factory loads anywhere in the normal websites i buy ammo and parts. I couldnt even find ammo for it on ammoseek.com.
Now looking at 6.5 grendel, it has about the same energy at 500 yards that 25-45 sharps has at 250 yards. Way better for deer hunting at any range if you ask me. Plus better sectional density so you getting the penetration you want with deer instead of bouncing it off of a shoulder blade and causing massive damage to meat with a ricocheted bullet or shrapnel. Sadly i had this happen ones with .243 winchester.
And finally onto 6.5 grendel's ammo availibility. The stuff is everywhere. Many small gun shops and larger retail stores i have seen it in. You can even get steel cased wolf ammo for some fun plinking for 24.5 cents a round. Not to mention some decent affordable hunting or target ammo from the main manufacturers.
My two cents is the grendel is the way to go and will last the test of time, we will see if 25-45 does.