338 GC bullet velocity exploratory thread

[Just Duke]

338 GC bullet velocity

I am wondering if I can get 2600 fps from 338 GC bullet. I know that a moderate load for a jacketed bullet will propel a cast bullet faster because of the gas seal.
Is this too fast for GC water quenched bullet. I would also have the option of adding lono type.
TIA:-D

Test rifle 338-06 Remington with Lothar-Walther 24 inch barrel
LBT 250 grain mould

[BABore]

It may be possible. The velocity looks a little fast for a 338-06 even with jacketed bullets, but I'm not that familar with that cartridge.

I've been working with a 338 Win Mag and a 230 gr bullet. I have had it above 2,600 fps using AA 3100. You have to play alot of games to get there. It's not all about the bullet's hardness either. The bullet fit to the case neck, chamber size, throat, and bore/groove dimensions all come into play. If the bullet is matched to all of those areas, then you are heading in the right direction.

I shoot a bullet that was designed for my gun. I tried the hard alloy route and started getting a grey (antimony) wash after about 2,300 fps. I ended up using an alloy of 50% WW's and 50% Pb and heat treating to 22 Bhn. Lube choice is also critical. Not so much for leading, but for accuracy. I settled on LBT Blue. It's easy enough to drive a cast bullet that fast. Its alot harder to do it with accuracy. I think I was running around 1 to 1 1/4" at 100 yards for 3 shots

Here's a lower velocity (2,230 fps) group using AA 5744;

[Just Duke]

That is some great info and thanks. If I could get 2300 out of a 250 grain bullet I would be very satisfied.

[Doughty]

Duke,

I have a custom built Ruger #1 with a Lilja barrel that is chambered in what I call a .33 Krag. (.30-40 Krag blown out to .338) It was chambered and throated with a close fitting reamer from Pacific Tool.

The bullet is from a mold I made several years ago using a cherry I made. (my third attempt at cherries and pretty rough) It is a gas check design, with about a .220 meplat.

I use WW mixed with some softer lead to come out with a 220 grain slug. These are heat treated and then run through a .340 sizer to lube and seat the GC. I use Gray #24 lube. The throat portion of the bullet is then sized to .339. I've found that for consistent performance the heat treatment must bring the bullets to at least 24 BHN as measured on my LBT tester.

The cases are neck sized with a re-worked .340 WBY sized for about 80 percent of the neck, and then step belled with a self made M die. I seat the bullet with a re-worked .340 WBY seater, not crimping, just taking the bell out.

I mostly use Remington LR primers.

If I hold the velocity to 2300 fps, I can get good accuracy with any number of loads. One good one is a compressed case full of Rel 19. I can go to 2400+ fps using AA2520 to the neck, then filling the neck with shotgun buffer before compressing it with the seated bullet. This load works almost as well without the filler, but throws the random flyer. This is my go to load for hunting.

I have experimented with going on up in velocity. I can get an accurate enough load at 2500+ fps but it gets mighty finicky about everything. And the recoil is more. And I still have to use a range finder for longer shots. And the animals aren't any deader. So I settled on 2400 +fps. I've thought many times of making another bullet that might give more accuracy at longer range and be prettier, but I still wouldn't be able to gauge the wind any better. I think that when you start shooting in the higher velocities with cast that your barrel (especially throats) wear pretty fast. At some point, continued experimention gains little in performance and just causes un necessary wear. I've got enough components now to keep this gal hunting for the rest of my life, so it's on to other things.

If I was a bolt action guy, I would probably have a .338-06. I think if you pay attention to details, that you can easily get a good load at 2300 fps, and with any luck, more speed if you want it.

[Larry Gibson]

Old Vic

What is the rifling twist of your .33 Krag barrel?

Larry Gibson

[Doughty]

Larry,

1 in 12.

[DonH]

Wish I had a 1-12 barrel instead of 1-10 for my .338-06. I have just begun to work with cast boolits in mine. The Lee boolit is a good fit in my rifle as cast from WW = 2% tin.

I don't see 2200 - 2400 fps as a handicap for rounds like these, especially with heavier bullets. Many medium bore rounds made great reputations at velocities in this range, like .333 OKH, .35 Whelen and numerous Brit rounds.

[Just Duke]

Ok, I caved, I am ging with 338 Lapua on CZ actions.