Home Forums Hunting & Shooting Long Range Hunting 338-378 with RL33 and 300 Gr SMK

Here is a load I worked up with the New RL33 powder 338-378 with a 300 gr SMK. I am going to run them at 3020 fps this load was just a touch too warm, but it was also hot outside too.3020 fps is a gr less. That is a serious can of whoop ass out of a 26 inch barrel !! 30 inch barrel I would be 3,100 + fps

What rifle you using? I have an Accumark 338-378 Weatherby and at 3000 ft/sec using 300 gr SMK, I have a hard time to extract the spent cartridge.It has a 28 inch barrel with brake. Are you sure about the accuracy of your chrono?

Yes chronograph is accurate and so are my long range drops. I have a factory accumark they are 26 inch plus brake.The best I could do before RL33 was 2920 fps that was RL25

I used 7828 SC compressed loads to achieve that speed. Like I said I had to back off due to bolt sticking at 3000 ft/sec. Are you FL your brass on reload? Can't figure out how you can do it and I can't. What brass you using?

The trick is the RL 33 have you tried it? weatherby/Norma brass, fed 215 primer, seated mag length at 3.80 ,yes I full length resize

I use the same primers and reneck only. I COL at 3.9, why is your mag so short? Mine measures 3.92. I will try the RL 33 and COL at 3.8, maye thats the ticket.

I'll check again but pretty sure 3.8 is about all my mag box allows. I really do think RL33 is getting my velocity up there.

I have been helping a friend that has a 338-378 with a new Bartlein barrel finished @ 28" with a proof research wrap. the only powder we have used is RL33 with 300SMK's and never hit 3K even with excess pressure, but then we are using an Oehler for a speed gun.

Hmm interesting how different rifles do different things. RL25 topped out at about 2920 fps without pressure signs.You would think with a 28 inch barrel 3000 would be easy in the 338-378 with a 28 inch barrel. 118.0 gr of RL33 gave me 3,020 fps with no sticky bolt lift or ejector button stamp.I was 20 feet from chrony and it was about 80 deg out.

With the new Bartlein he probably doesn't have the factory weatherby freebore right? If that is the case the pressure will be quite different

Well I can't figure out how you can get over 3000 ft/sec when my bolt wants to lock up at 2900 ft/sec in the same rifle shooting the same 300 grain SMK bullet?????

Did you work up some loads with RL33? Before I used RL33 I could not reach that velocity.

Probably just have to mark it up to the black magic we all see with rigs shooting the same loads at different speeds. I'll never understand it either.

FWIW, Quickload shows a little less than 2900 fps with RL 33 as max with the specs you gave.

That's some performance.

Speaking of big 338s, one of the local LR guys is running the 300gr Berger Hybrid at 3200 fps. He's using a blown out 338 Lapua case, N570, and a 32" barrel.

RL 25 and 33 do things that other powders can't quite match. 25 is a wonderful 300 H&H/WinMag/Weatherby powder in a correct barrel (26" minimum) and 33 works very well in the big 338s.
As several have pointed out, the barrel means a lot. There is a world of difference between a conventional 4 groove 24/26" and a Nitride treated 30/36" 3 groove.
A 245 gr 338 Bore Tech bullet easily exceeds 3000 fps in a 338 Lapua or RUM carrying a state of the art long barrel and shoots flatter to 1000 or more than any 300 gr Berger alternative. BT BC is .869 Berger is .818.
RL 33, Retumbo or H 869 will do it.
Not "hunting rifles" but still lighter than a Barrett.

Yeh that 3200 fps rig is using the +P version of the Lapua improved right?I am very impressed to go over 3,000 with a 26 inch barrel the RL33 does seem to working as claimed.But all that being said if it doesn't shoot as accurate as my 2920 fps load it doesn't matter because the accuracy load I have found with RL25 will be the go to.

Yes, I guess you know I'm talking about Broz's rifle. 338 Terminator +P.

I just acquired a WBY Accumark in 338-378 . What would be the starting load with Re#33 and a 300 gr bullet ?

Hate to jump in when not asked but if you go over 2800 ft /sec with that 300 smk in that 338/378 you will see that bolt starts sticking and cratered primers. i have the exact same rifle. No matter what powder you use. Have you an accurate bullet speed equipment?

Please jump in thank you . Yes I have a two chronographs . So what loads do you prefer ? Do you have the same factory brake,or an aftermarket ? I have a PVA 4 port shock wave 30 caliber I'm thinking having that opened up for 338 or buy a 5 port baffle brake . 117.5grs of RETUMBO pushing a Hornady 230gr ELD-X was above max. I just loaded up some 107grs of H1000 behind same bullet waiting to be fired .

Not RL-33, but Retumbo and a 300gr Accubond will run 3000 fps out of my custom 338-378 with a 28" Kreiger barrel, the load is simply not fun to shoot, i'll admit to settling on 2900 fps with H-1000 and 2850 with H-4831, the two lesser loads are much more easy to shoot accurately, are a bit more accurate than the full bore hellbender Retumbo loads, plus, if you really get down to it, 300 grs at 3K or 2850 doesn't matter one bit, maybe a tick or two more elevation and wind, but i'll guaran-damn-tee you the game wont give a chit!

What kind of brake do you have on your rifle ?

Don't forget to take altitude into consideration. My son has a 338x378 with a 9 twist 30" barrel.
He has trouble getting 3000 fps with a 300 gr in PA at about 1500' elevation.
106 gr of Retumbo which is pretty much max in his gun is 2950 fps.
RL 33 dosent work for him. Most guys are using 250s for hunting and claim they work better to about 1500 yds.

Don't forget to take altitude into consideration. My son has a 338x378 with a 9 twist 30" barrel.
He has trouble getting 3000 fps with a 300 gr in PA at about 1500' elevation.
106 gr of Retumbo which is pretty much max in his gun is 2950 fps.
RL 33 dosent work for him. Most guys are using 250s for hunting and claim they work better to about 1500 yds.
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I've the original brake on it. Works fine, didn't find any need to change it.

I figured all the 338/378 Accumark had factory brake when sold. The year i purchased mine anyway.

Yes I have the factory brake on mine. But I have a PVA 4 port Shock wave I think I'll try ,to see if I can reduce it even more.

If you're talking to me Ironworker, none, all 28"s is barrel.

I didn’t see ant load data for R33 in the 338/378 on their website. Had it for the 338 Ultra Mag and Lapua.

I.have three of.the weatherby 338-378 rifles .I used them in Alaska 12 years they are awesome.I always used 250 grain nosler partitions for it .They shot awesome groups were 1/2 inch.at 100 yards and recoil was very light with the brake on.I used them because of the bears in Alaska .Target bullets were not good for bears .I shot targets with the 300 grain serria but I didn't like the recoil .I read where you could get 3000 fps from wc867 powder in the 26 inch barrels with 300 grain bullets .The 338-378 needs a 30 inch barrel to burn all that powder it's just carrying one that long is a pain in brush .Those are very nice guns .

So you shot a Bear with one ? Tell us the story . I'm loving mine,waiting on a 5 port baffel brake now. Factory brake does an ok job,I just know there are better brakes out there.

Better how?

Doesn’t the factory brake have holes all the way around the bore? If you ever shoot one prone and feel the debris blown up on you and scope, you will get a side slotted brake with no holes on the bottom. Ask me how I know.

Hey Kahuna How many animals have you shot laying on a blanket?

None on a blanket, but I’ve shot a few laying prone on the ground useing a bipod. Which has nothing to do with the difference in brakes that were in discussion. Apparently you’ve never shot prone on a bipod or you would get the point why the difference in where the ports are located.