My take aways...
The 200 Fusion load is a screamer. it'll do 2600 and small change out of a 22" tube, and at 25 bucks a box its the cheapest load to shoot for brass. The factory 210 PT load only steps at 2490's as did my reloads (at least the ones that didn't loosen primer pockets after a couple loadings)
You can run 180 NABs at a legit 2700 FPS, but neither one of the 338 Federals I had much liked that pill.
TAC ain't the magic pixie dust that its cracked up to be. One gun ran substantially slow with that powder and the other flattened primers and made for a very sticky bolt lift once it was loaded with enough TAC to shove a 200 Hornady 2550 FPS.
RL15 and H4895 are your huckleberries with the 200's, and Benchmark can shove the 180s spooky fast if you use Hodgdons data. Both my 338 Federals (one was a Tikka T3, and the other a Kimber Montana) loved 200 grain Hot-Cors over 46 grains of Swedish made RL15, lit off by a Federal 210 and an OAL around 2.800". I substituted 210 Partitions for Montana's General Season. Both loads shot into 1/2" vertical of each-other at 100 and right around 2500 FPS
Necked up WW 308 brass is a lot thinner in the case head, and the necks thin out to around .012-.013" It don't last that long... You can get away with stuffing about a half grain more powder in it though and milking it for another 50 FPS if you're so inclined. Military 308 brass (I used LC-05) necked up very closely duplicates FC 338Fed cases in neck thickness and head design, backing off the said loads 1/2 grain gave similar velocities and I would assume pressures... It'd last about 7-8 firings before you'd start to see case head seperations (which is pretty typical in a 308 if you don't neck it up...) The WW brass I necked up only lasted 4-5 firings and the necks would split (and I was barely working them with a TiN coated bushing in a Redding type S die)
So yeah... What I said in the other post on this thread... In the real world its a 300 yard Mini Sledge on critters up to Elk. And with the 180 NABs its a 30-06 with 03-A3 50,000 CUP 180 factory loads (as long as we're talking about 180's with a BC under .400)
In the end though, I already had a Montana in 308 that was a lot cheaper to feed (and can run a 180 Partition at 2600 and change if I need it too.) And I really wanted another 260
I know I don't have to explain to you why I like 6.5's
