338 Ultra Mag Info

[Dick Tinsley]

At what distant is that an what bullet weight?

DT

 

[Timber338]

Great thread, tagging in. I'm currently waiting on a custom 338 RUM, and all stocked up with RL33, so all kinds of useful info here. Also have a whole bunch of different bullets, but the one I'm going to start with is the Berger 250 Elite Hunter.

USCGLongBow ... your comment that RL33 feels like more recoil, that would make sense since you are stuffing so much more in there compared to RL22 and 25, right? I think the average velocity of the powder leaving the barrel is about 4000 fps, so it doesn't take a whole lot more powder to increase recoil. Also, your thoughts on the 33 not burning, what barrel length are you shooting? I'm sure it's real close either way.

 

[bigngreen]

Reloader 33 is to slow for a 250gr or smaller in the 338 RUM, a 300 grain you would be gaining maybe.

 

[USCGLongBow]

USCGLongBow ... your comment that RL33 feels like more recoil, that would make sense since you are stuffing so much more in there compared to RL22 and 25, right? I think the average velocity of the powder leaving the barrel is about 4000 fps, so it doesn't take a whole lot more powder to increase recoil. Also, your thoughts on the 33 not burning, what barrel length are you shooting? I'm sure it's real close either way.

At what distant is that an what bullet weight?

DT

You are stuffing an additional 12gr of powder into the case, so yes, but I don't see any velocity or accuracy increase with that. I'm shooting a 700LSS with a 26" barrel, the entire rig weighs 7 1/2 lbs. It is really close to completely burning. Unlike some powders, this didn't leave any unburnt powder flakes. For a longer barrel, probably a great powder, but if you are shooting a stock gun, you might not see a lot of gains.

I just shot at 100yds because that is the longest distance at the local range currently. I was shooting a 200gr Ballistic Silvertip.

I will try to take the chrono and shoot a few RL22 and RL33 one of these days, but published data suggests the velocity with both powders will be about the same.

 

[Timber338]

Reloader 33 is to slow for a 250gr or smaller in the 338 RUM, a 300 grain you would be gaining maybe.

This very well might be the case, but I've got the powder and bullets so it's what I've got right now. Once I get the rifle I will definitely report back with results to confirm this one way or another and will be fun little experiment. I do have some RL25 and H1000, so I will be able to compare and see what my gun likes the best and how the velocities play out.

 

[USCGLongBow]

Reloader 33 is to slow for a 250gr or smaller in the 338 RUM, a 300 grain you would be gaining maybe.

Exactly right, the lighter bullets just don't have the mass to give RL33 time to build speed. If you look at printed data for it, the velocities between 250 and 300 are really similar with this powder.

 

[Timber338]

Exactly right, the lighter bullets just don't have the mass to give RL33 time to build speed. If you look at printed data for it, the velocities between 250 and 300 are really similar with this powder.

Well now you just gave me an excuse to buy some 300s! gun)

 

[Dick Tinsley]

Well now you just gave me an excuse to buy some 300s! gun)

Just wondering how long you gonna keep that arm in a sling to heal from being twisted!! LOL!!!!!

 

[bigngreen]

A case FULL of Retumbo under a Berger 250 is impressive, you shoot a 300gr at 2800fps then throw a 250 down range at 3100 fps and it kinda surprising just how fast it get there!!

 

[Dick Tinsley]

A case FULL of Retumbo under a Berger 250 is impressive, you shoot a 300gr at 2800fps then throw a 250 down range at 3100 fps and it kinda surprising just how fast it get there!!

Plus one on the Retumbo an a 250 grn!!!

 

[Timber338]

A case FULL of Retumbo under a Berger 250 is impressive, you shoot a 300gr at 2800fps then throw a 250 down range at 3100 fps and it kinda surprising just how fast it get there!!

Thanks for the tip! I actually think the 250 at higher velocities is the better bullet for the rifle I'm building and the ranges I will be using it. So my money will be better served in finding the right powder. I'll keep my eyes out to try and find some Retumbo in stock.

 

[HARPERC]

A case FULL of Retumbo under a Berger 250 is impressive, you shoot a 300gr at 2800fps then throw a 250 down range at 3100 fps and it kinda surprising just how fast it get there!!

The 180's at 3500fps get there right now. What they do to an antelope is impressive.

H-1000 works well for me. 7828ssc hasn't impressed me yet, but I've had other issues to work through so it could be just timing.

As near as I can tell, the ogive on the .338 Accubond is identical. From 180-250 no die changes needed, they just added more length in the middle.

 

[Timber338]

Got great news from my gunsmith today.... he's a couple months ahead of schedule and my 338 RUM is going to be ready in 6 weeks!

Since I have RL33, I am going to try it out with the Berger 250. I just looked at Alliant's website, and they list a max charge of 106 grains with a 250 gameking and a 3.59 OAL. Can anybody recommend a safe starting charge? Right now I was just planning on 100 grains to break in the barrel and get a feel for the gun, and then move up from there. Do you guys have different advice here? I've got GM215M primers and Nosler brass, and planning on starting the bullet .005 from the lands, obviously not exactly sure what that OAL will be until I get the rifle, but it's going to be longer than 3.59. Never reloaded for any RUM case, so this huge case capacity is new to me. Should I go lower than 100 grains?

 

[HARPERC]

I thought I was going to be able to help. I just bought a new Berger manual, and it stops with the .30 calibers.

I found no source for R-33, hopefully someone will have it.