Well, of course they would say that about their .408 bullets in .410 grooves. But those PDR bands are pretty slick and minimal drag and less likely to grab in a .410 groove than would be a grabbier bullet with greater bearing surface and start pressure.
My Douglas .410"-grooved barrel that has a .400" bore/land diameter, 1:14" twist, stainless, is on a CZ 550 Magnum .410/404 Jeffery wildcat. I could try those .408" Hammers in that. Such a tight bore might make it work with loose grooves.
I also have a .408 Chey-Tac sporter on an MRC M1999 action with Dan Lilja fluted 1:13" twist and a .408/.338 Lapua on a BRNO ZKK-602 with McGowen 1:13" twists. Both of those are .408"-grooved/.400"-bore/land diameter. Come to think of it, Chey-Tac used to sell a pointy 300-gr/.408-cal monometal copper solid bullet. They called it the "Battlefield Dominator" bullet (anti-personnel) and paired it with the 400-grainer for anti-materiel.
The 296-gr/.408-cal/1.5mm-HP Pittman Hammer might be a "Gamefield Dominator" in any of the above rifles.
For peace of mind, push a 300-gr/.411-cal TSX through a .408" sizer and I bet it would spring back to .410" diameter and stay there. I'll swap you those for any .408-cal bullet leftovers you try and find unsatisfactory. Bullet for bullet, or will work for food.
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.
