338 Ultra Mag Info

[bigngreen]

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?

The best thing to do is just load up what the manual says, one round working up in 1 grain increments till you get a hint of pressure then back of a couple grains and start working from there, I usually do it with a chronograph to also give me an idea of velocity. You'll waste less rounds and you'll be working in the range you want sooner, you can waste so much powder ***** footing around with it!!

 

[Dick Tinsley]

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.

I also have no data with the RL-33. USCG Longbow seems to be testing with the RL-33 an having good results. The best I've got is with H-1000 an Retumbo. 101gr of H-1000 an 100gr of Retumbo! With the 250 AccuBond's my 338 shoots bugholes! Again I havnt tested yet with the 200&225's but will soon!

 

[Doublezranch]

Timber,

The large case capacity case the RUM has is very easy to read. Too light of charge will not seal the chamber and blow powder residue everywhere. Pressure signs are easily seen on that big case. It's best quality I have seen so far is it's broad min to max charge range. As mentioned I shoot the 265 lrx with awesome long range accuracy. I shoot 88 grains 7828 ssc which is a top load for that powder but then again IMR designed 7828 for the stw. My longest kill is 880 with this combo. My barrel is losing it's accuracy life soon so my plan is to switch to either 300 Berger or 285 lrx with 33. I like my 7 rum, love my 300 and 338 rums, and my 375 rum makes me laugh when I shoot it. It's just a easy and fun big bore case to shoot. You will love it.

 

[Timber338]

Thanks guys. I don't think any manual exists with RL33 and a 250 berger. I bet the safest approach is to call Berger and ask them, but I feel safe with the data points I got off of Alliant's website that lists RL33 with a 250 grain Sierra match king, 215 primers and a federal case that lists 106 grains as a max. I'll be seating the berger out further than alliant seated the match king, and dropping 6 grains down to 100 should be a good starting point. They also list a max charge with a 300 grain match king at 99.3 grains, and a third data point they give is a 250 grain partition with 103 grains. So I think seating my bullet out near the lands and starting at 100 grains is going to be very safe place to start. Still got several weeks to think it over, so I will definitely give Berger a call as well.

 

[Timber338]

Timber,

The large case capacity case the RUM has is very easy to read. Too light of charge will not seal the chamber and blow powder residue everywhere. Pressure signs are easily seen on that big case. It's best quality I have seen so far is it's broad min to max charge range. As mentioned I shoot the 265 lrx with awesome long range accuracy. I shoot 88 grains 7828 ssc which is a top load for that powder but then again IMR designed 7828 for the stw. My longest kill is 880 with this combo. My barrel is losing it's accuracy life soon so my plan is to switch to either 300 Berger or 285 lrx with 33. I like my 7 rum, love my 300 and 338 rums, and my 375 rum makes me laugh when I shoot it. It's just a easy and fun big bore case to shoot. You will love it.

Thank you, this is excellent feedback. I am excited to jump up to the 338 RUM. I am primarily an elk hunter and have always hunted with 338 caliber bullets. I think the RUM is going to be a real hammer. Out of curiousity, do you install brakes on your RUMs? I am going with a CSR 3 port since my barrel is only a #4 contour I cannot go with the larger muscle brakes.

 

[bigngreen]

Thanks guys. I don't think any manual exists with RL33 and a 250 berger. I bet the safest approach is to call Berger and ask them, but I feel safe with the data points I got off of Alliant's website that lists RL33 with a 250 grain Sierra match king, 215 primers and a federal case that lists 106 grains as a max. I'll be seating the berger out further than alliant seated the match king, and dropping 6 grains down to 100 should be a good starting point. They also list a max charge with a 300 grain match king at 99.3 grains, and a third data point they give is a 250 grain partition with 103 grains. So I think seating my bullet out near the lands and starting at 100 grains is going to be very safe place to start. Still got several weeks to think it over, so I will definitely give Berger a call as well.

Berger has the 338 info on the web site but it's so conservative it's almost useless IMO, you can basically use Retumbo as a guide line for R33, I usually take the Retumbo load and start mid way to the upper end of it for R33 then I'll let the rifle tell me when I'm getting to the top end.
The 250 Berger has a very short bearing surface compared to any other bullet you'll use in that weight range so that will also have you needing to up the charge a bit!

 

[Doublezranch]

Yes. I use Assassin brakes. After experimenting with a few different ones, I found the Assassin does everything and more. For instance, I have a custom 300 rum that eats 102.7 grains of 33 that blows out the 230 Berger 3200 fps. Calculated recoil on that load is close to 50 lbs. I installed a Assassin brake and it tamed that recoil down to 17 lbs. Since I had great success with reduction, I placed one on the rest of my fleet, one on a gun I had built for my father, and a one-of-a-kind assassin made for my 12 year old son's 270 wsm. If you do a search on this site for assassin brakes, you will get more info. Otherwise, J E Custom is valued member here. He is who makes them. Give him a holler. Here is a picture of my 300 rum with the brake.

 

[elkcoast]

I run basically 3 loads: 180 Accubond with 100 grains of R22, 225 Accubond 100 grains H1000, 250 Accubond 98 grains H1000. All using Federal 215 primers

No trouble getting them to shoot. The 180's will get you 3500fps, reduce recoil, devastate small deer and antelope to 600 yards, pretty good rock shooter.

The 225 will get you about 3200fps. Mostly used these before the 250 was available. Kind of too much in the middle for me. Penetration not as good as the 250's.

The 250's will run 2900fps, start to be an advantage on medium, and larger game. My rock shooting seems to beat out the lighter weights from about 750 yards on.

If you're running a lighter weight rifle, the 180's are just more fun to shoot.

The 250 gr will get you 2900, but the hodgdon site only advertised the 225's at 3060 with 100 grains of H1000. Of course higher elevations will get you better.

 

[HARPERC]

The 250 gr will get you 2900, but the hodgdon site only advertised the 225's at 3060 with 100 grains of H1000. Of course higher elevations will get you better.

You're correct, it should read 3100, internet gremlins, club fingers, and less than stellar eyesight.

Nosler #6 is where my load originated, and it lists 3125 for their results with a 26" barrel, and 215 primers. My chronograph at the time was just under 3100 with the screens at 20'. Rounded to 3100.

I don't have the Hodgdon that lists a 338 RUM, just curious what barrel length, and primer they chose? I suppose one could crack 3200 with that powder in a 28-30" barrel. But a change to RL25 if you have some would be a better choice , and 3200 is your goal.

Beware Internet loads, Thanks for the correction.

 

[elkcoast]

You're correct, it should read 3100, internet gremlins, club fingers, and less than stellar eyesight.

Nosler #6 is where my load originated, and it lists 3125 for their results with a 26" barrel, and 215 primers. My chronograph at the time was just under 3100 with the screens at 20'. Rounded to 3100.

I don't have the Hodgdon that lists a 338 RUM, just curious what barrel length, and primer they chose? I suppose one could crack 3200 with that powder in a 28-30" barrel. But a change to RL25 if you have some would be a better choice , and 3200 is your goal.

Beware Internet loads, Thanks for the correction.

Yes, I believe one could crack 3200, especially using the RL25, or perhaps RL22. I have not had any personal experience with the .336 calibers. I have been using the not so popular (but awesome in my personal experience) 8 mm mag. Similar speeds, powders and recoils I'm sure.
The barrel they used was Remington 24" 1:10 twist with rem 9 1/2 mag rifle primers...so the 26" should do a bit better. 28-30" would be awesome.
My 8mm with 220 Sierra game king is doing a piddling 2978, but it still works.

 

[elkcoast]

Yes, I believe one could crack 3200, especially using the RL25, or perhaps RL22. I have not had any personal experience with the .336 calibers. I have been using the not so popular (but awesome in my personal experience) 8 mm mag. Similar speeds, powders and recoils I'm sure.
The barrel they used was Remington 24" 1:10 twist with rem 9 1/2 mag rifle primers...so the 26" should do a bit better. 28-30" would be awesome.
My 8mm with 220 Sierra game king is doing a piddling 2978, but it still works.

ooops, meant 338 caliber.

 

[Dick Tinsley]

Mabey someone can help! The load I'm shooting is 100grn of H-1000, 250 grn AccuBond, fed 215 primer, 28" Pac-Nor 1n10 twist! Never crony it, just reserched an worked up a load in incraments. Can someone run this an kinda give me a idea on veloisity? It may seem like a hot load, but it is very accurate! Thanks!

DT

 

[HARPERC]

Mabey someone can help! The load I'm shooting is 100grn of H-1000, 250 grn AccuBond, fed 215 primer, 28" Pac-Nor 1n10 twist! Never crony it, just reserched an worked up a load in incraments. Can someone run this an kinda give me a idea on veloisity? It may seem like a hot load, but it is very accurate! Thanks!

DT

There are lot of variables with this powder, this bullet weight, and this cartridge. Mixed in with that is the feeling by many, the newer H-1000 is hotter than the old.

I went to load data.com and found the following maximum charges and velocities, for 250 grain bullets:

1) Berger, 89 grains/2788 fps
2) Handloader, 90 grains/2645 fps
3) Barnes #3, 92 grains/2833 fps
4) Barnes #4, 93 grains/2771 fps
5) Swift, 93 grains/2777 fps
6) Lee, 98 grains/2923 fps
7) Hodgdon, 98 grains/2923 fps

I've shot/chronographed the 98 grain grain loads right at 2900 fps. That was quite a while back with an older lot of powder. Nosler doesn't list this powder on their site.

I suspect Lee just borrowed from Hodgdon as they are identical.

I'll guess and say you're pushing 3000 fps. and are red lined at least, over at worst. I haven't seen a 100 grain listed for 250's in any source over the years.

Now that I have some RL-25 on hand, I won't use the H-1000 much in this cartridge.

 

[Dick Tinsley]

HARPERC! Thank you for your info! After lookin in the Sierra manual ( Edition V 5th printing) they list 99 grns of H-1000 As max. As I stated I started low an worked up an it just kept gettin better. When I stopped at the 100grn load the accuracy was outstanding. Never showed signs of pressure, but I stopped there because its just so accurate! Again! Many Thanks for your help an input!!

DT