Hornady use their own proprietary powder to get 2150 -2190 fps with 500 gr. You can do the same with handloads although someone will be along to tell you that I am talking rubbish in just a second. Lott factory rounds will make 2250 to 2300 fps and I have personally got 2350 fps with a handload although in Zambezi Valley heat, that load is overpressure.A good buddy of mine has a 450 ackeley, he uses 458 lott ammo since he cannot source the ackeley ammo.
A client left some 458WM ammo for him and some 300WM ammo behind about 18months ago. He chrono'd the Hornday WM vs some Lott ammo and had faster recorded speed with the WM over the Lott in his ackeley.
Accuracy was more than dependable, it was as good as anything was supposed to be.
Any ideas (or guesses) as to why that would be?
I regularly shoot 458 win mag in my Lott. It is a win mag reamed to Lott. Interesting fact is that a standard win mag has a very long throat anyway- Longer than a factory Lott chamber. So the reamer just took the chamber a little longer.
I cannot see any practical difference in accuracy. People can pontificate about MOA accuracy in large bore rifles but I have never met the man who can cloverleaf a 458 -even at 50 yards- with any regularity.
So is a 458 win mag less acurate in a Lott- Not that I can tell.
Does it leave any noticeable ring in the chamber not that I can see. I clean with a pull through and the chamber is shiny and clean. Throat erosion- as I said above, the original win mag throat is longer than the Lott throat so I dont see that it will erode any more than standard. Also these calibres are not speed freaks or highly overbore so throat erosion is not much of a worry to me. If I am lucky enough to shoot out the barrel on my Lott, I will consider myself very lucky to have shot so much !