New .284

[SDMF]

I know I'd like to get my hands on some of those hybrid cases. I don't think it would be hard to size / form them into 6.5 Creed. Stuff it full of Varget, or maybe something faster, and break 3100 FPS with a 140.
-- I can already hit 3000fps with Reloder 26, but I have to vibrate each case to get all the powder to fit in there.

Have you tried a longer drop tube?

 

[Downrigger]

I ran into issues with pressure on my 20 tac, and was a little surprised when I tried vibrating. Sucks because that barrel likes it hot.

 

[svnmag]

If your 1st “cold bore” shot is measurably outside your average group as thr bbl warms, IMO you’ve got a mechanical problem.

Scope bases
Scope rings
Bedding
Action screws

Or, less likely, you’ve got some stress in the bbl steel and you need a cryo treatment or a new tube.

Going back and forth between copper and cup and core projectiles doesn’t cause trouble in a good barrel either. Tuesday I shot a .270Win I bought used. It’s got a 6x42 Leupold in Talley lightweights. 130gn Hornady interlocks and 130gn TTSX with the same powder charge and same seating depth into the same group. Doesn’t matter if it’s cold or HOT just keeps pounding bullets into the group. As an aside, this is from the 2nd worst looking bore interior I’ve scoped.

Well maybe I've been overthinking things. It may have come from the 77 vertical stringing as the bbl warmed. Probably shot it a bit too hot...anyways problem solved after floating, bedding and trigger job...and never shooting a group from a warm bbl...

Give or take, once you go over 55K PSI in any brass case, your primer pockets have a "lifespan".

You can keep the neck and shoulder "alive" almost indefinitely by proper sizing and timely annealing, but, get up into the low-mid 60K PSI range and primer pockets don't last forever. Some last longer than others, but, they all eventually fail to crush-fit a primer.

80K PSI is up in the range where in a brass case you pierce the primer, flame-cut nice little "pits" into your bolt face, and get a face-full of escaping gases. And/or the primer-pocket fails completely and when you open the bolt (if you can) the case comes out and the primer falls down into the magazine or trigger mechanism.

It's hard to say, but, it might make more sense to people if we got rid of "caliber headstamps" like 308Win and instead called out cases by their projectile diameter, case length, case capacity, and PSI ratings. If you've got a bore diameter, case capacity, and max PSI it becomes more difficult to be enamored with a "head stamp" as something magical.

The 308 x 51 x 56 x 62,000 doesn't exactly roll off the tongue like "308 Win" or "7.62 NATO" though.

It'll be interesting to see as more steel case offerings and reloading tools become available how the manufacturers go about dealing with the steel portion of the cases. Previous to the .277Fury or this new 7 BackCountry, the way to deal w/steel cases was to lacquer the cases and chrome line chambers and bores. Currently it looks like nickel-plating at least the steel portions of the case is how they get around "stickage". At bottleneck cartridge pressures, nickel eventually flakes off though. When that happens you run the risk of galling dies, or worse, chambers, bolt-lugs and/or bolt race-ways.

I'll admit, that a modest 22" bbl with what most consider a fairly "short" 6" suppressor, isn't nearly as "handy" as a straight 22" overall bbl length.

Good info. I meant developing loads/bbls for steel cases.

 

[SupressYourself]

Have you tried a longer drop tube?

No. I just backed off the charge a bit.