Sir Roo,
The 500-gr TBSS in Federal factory loads
would be a great comparison of .458 WM to .458 Lott,
both fired in same R8.

You will not lose much by firing the .458 WM in the .458 Lott chamber,
compared to .458 WM fired in .458 WM chamber.

The extra slop in the Lott chamber is partially compensated for by the shorter distance from breech face to rifling contact in the Lott chamber.

Ron aka "Rip" for Riflecrank Internationale Permanente
NRA Life Benefactor and Beneficiary
.458 Winchester Magnum, Magnanimous in Victory
THE WALKING DEAD does so remind me of Democrap voters. Donkeypox.