That was the starting point for the Cheytac cases but the 505 wasn't set up for as much pressure.
Bore alone is a really poor metric for ELR cartridges. Case capacity to bore ratio is only an entry point, it's not the answer. If you limit the discussion to bullet weights that more or less scale to bore, there is a slight trend favoring the larger bores. 338, or even 30, to 375 isn't nearly enough to cover 1 shooting position's worth of conditions luck though.
I mentioned the RPM problem on the small end earlier. The 37XC will pick up performance relative to the larger 375CT because the smaller diameter allows more pressure. Not enough to cover the loss in case capacity, but not as bad as the first cut suggests.
Another boundary is the upper limit of case volume that a LRM primer can set off before the BMG primer is a better idea. That was thought to be more or less the Cheytac case for a long time. The latest ELR wonder children are pushing that by using a long tube Cheytac case then limiting themselves to the 215M primer, single base powders, and/or temperatures above 40-50 degrees. The problem I see is to step up to the 416 bore, you'll need almost the 416 Barrett case capacity to maintain the 375 Cheytac performance levels. There will be some allowance for the higher pressure the smaller diameter case allows but I don't see the payoff.
What about the 416 Hellcat shooters that are doing well? Those guys are doing well because they're executing the fundamentals better than the rest. From the reloading bench to their shooting strategies. If a new ELR shooter thinks they'll skip a couple steps by buying a gun chambered in that round, they're in for a very rude awakening the first time they shoot with someone serious. I don't compete much, but I've seen that play out many times. Usually, they don't come back.
