Just got it, now I need a little help...

I can't give you any advice about the .308, but I have been using the 160 gr Accubonds in my custom heavy barrel 7MM RM. I currently use 59.0 gr of IMR 4831 and WLRM primers which is not very hot, but it shoots ok out of my gun. I have not experimented with it since I loaded those up but if I remember right, it's shooting under 3/4 to 1/2 MOA without me going back and checking. The velocity is only a little over 2850 fps out of a 26" barrel. I was always going to try the Berger VLD's but when I was shooting the 7mm I couldn't get my hands on any of them. RL-22, or IMR 4350 also shoot good out of my rifle.

As for cutting off your barrel.... I can't remember how many fps in general you gain per inch but I thought it was somewhere around 100-150 fps or so, and I don't know how fast you can push that .284 bullet out of a short barrel like that ether. I would think that it would not be too much below what the published numbers are.

The bottom shot was to get on target, the top hole I'm claiming as a "Flier". This is my 7mm Rem load with the 160 Noslers.

I'm sure someone else will chime in with some further information. Hope you didn't forget the seater dies!

Sounds like you may be planning to do some shooting?

To answer your middle question first, because peak pressure occurs about one to two inches into a bullet's travel down the bore, unless you have a barrel shorter than that, you can't get increased velocity from faster powders for a given peak chamber pressure. For normal barrel lengths, the powder that is fastest in a long barrel will also be fastest in a short barrel. Fast powders produce lower pressures after the peak because they burn out sooner. That drops the pressure that follows the peak as compared to a slower powder. This can improve accuracy by presenting less muzzle blast to the base of a bullet, so the highest velocity load you can find is often not the most accurate. You normally lose 20-40 fps per inch of barrel in most guns, but the exact number is individual to the powder charge and bullet used, and also to the barrel lengths you make the comparison with.

For the .308 accuracy work, I've had excellent results from Varget, IMR4895, IMR4064, Reloader 15, Vihtavuori N140, Winchester 748, and Accurate 2520 (deburr case flash holes for this powder and for 748) at different times and ranges. Ramshot TAC and the new Reloader 17 look promising on paper, but I haven't wrung either out yet. Varget is probably what I would pick to start with. It will span your whole bullet weight range. It is bulky enough that it won't quite give you the velocity IMR4895 or 748 can, but it has good temperature immunity and is less picky about primers in the .308, and that cuts down on some of the variables while you get started.

What cases will you use? .308 case brands vary in capacity by about 3 grains, so the brand is critical to load data. All the data on the Hodgdon site uses Winchester cases, as do the OCW loads listed on Dan Newberry's web site. They have the most capacity. I like Newberry's round robin method of load evaluation, BTW. I think you'll find reading his whole site useful. It would be a good place for you to start looking at loads.

Be aware the old 168 grain SMK, originally designed for 300m International Rifle shooting in the late 1950's, is only good to 600 yards. From a .308 tac rifle I've watched it go unstable and tumble before getting to a 750 yard popper target. At the Long Range Firing School at Camp Perry, nobody using it could stay on paper at 800 yards. Same problem. At .308 velocities, somewhere around 650 to 700 yard it gets into the transonic range and becomes unstable. The newer 175 grain Sierra MatchKing, designed in cooperation with the military for sniper ammo, does not get unstable in the transonic velocity range and has made hits to 1200 yards and beyond in the sandbox. I've switched over to it for long range, and no longer buy the 168's (though I'm still using up my last 1000 or so from very large old bulk purchase).

I haven't tried the 155 grain Scenar or the new version 155 Grain Sierra which matches the Lapua's BC's. That's another one you might look for.

I'll leave your other chamberings to those who own them to address.

Federal has a reputation for being soft. If you've had time to read his site, you'll have noticed Dan Newberry doesn't consider it suitable for reloading at all because of that. The Lapua cases, at the other extreme, are the best you can get and will last a very long time if you keep the necks annealed.

That said, if the primer pockets on your GMM brass were not shot lose by their original loads and you aren't going for a maximum load, you should be able to get some more work out of them. If you find the primer pockets getting loose, though, pitch them.

I can tell you the old Federal GMM .308 load for the 168 grain SMK was 43.5 grains of IMR4064 over the Federal 210M primer. This runs about 52,700 psi and is slightly compressed. I understand they now use Reloader 15, as Lake City does for M118LR with the 175 grain SMK, but I haven't pulled any to study the load as I did with the older stuff? Based on tearing down and duplicating the old Federal load, it appears to me they used a burn rate adjusted canister grade powder, like reloaders buy, rather than the usual unblended bulk powder manufacturers normally use. It makes sense from the standpoint of consistency for match grade ammo, but still, that is an inference and not a proven fact, so if you are going to try it, work up from 10% lower, watching for pressure signs, just to be safe.