338 RUM performance

[D.Camilleri]

Resize your brass and see how the primer feels. Personally I think you will have better results with slower burning powder. The newer lots of H-1000 are giving me 3300 with a 225 accubond with 97 grains. 95 grains of reloader 25 is similar. Work up to these and watch the extractor marks.

[lonegunman762x51]

I have been testing my 338 RUM for a couple of months, I have had good luck with Hornady 225gr SST's and Reloder powder. I am getting right at 3100-3150 fps and under 1.5 inches at 200yds. My rifle is heavy, a Shilen #7HV barrel, Remington action, Leupold long range scope and McMillan stock.

I've been fiddling with different bullet weights and powders to see what the gun likes. It is a heavy rifle and running 30-40 rounds thru it is no problem. I'm not a big brake fan but this gun has one. It is not as bad as some types but it is still loud and makes earplugs a must, especially when hunting.

I went with the 338 RUM for a couple of reasons. 1. it easily duplicates 338 Lapua and fits in a long action without mods. 2. the cartridge has no belt, rebated rim or any other odd feature of some large cartridges.

Recoil for a few shots at some critter is never a problem for me. I built this gun a bit heavy because I wanted to be able to run quite a few rounds through it without suffering. In all honesty it is about as hard as my .308 chassis rifle.

I am planning on hiking into a mostly flat mule deer area and using it past 800yds. Every deer I have scene in this area is so far away it is not funny. The good news is that some of them are quite massive.

[blackaj]

Originally Posted by D.Camilleri

Resize your brass and see how the primer feels. Personally I think you will have better results with slower burning powder. The newer lots of H-1000 are giving me 3300 with a 225 accubond with 97 grains. 95 grains of reloader 25 is similar. Work up to these and watch the extractor marks.

Thanks I'll try resizing to see if the primers are loose.
That's interesting you were able to get 3300 fps with the 225's and 97 grains of H-1000, the Hodgdon reloading data lists a max load of 100 grains with the 225 Partition at 3058 fps. I do like H-1000 powder in my 7mm, I'll give it a try.
What primer, and seating depth were you using to get that velocity?

[jlrookstool]

I have also loaded H1000 at the same grains as retumbo and chronnied only a few fps different. Sierra's new book says I'm about 3 or 4 grains short of their suggested max loads. I always shoot about 150 fps faster on average depending on the bullett and load than the book does. I think my chrony is ok as my experience matches Brian Litz's Shooter program very closely. At your sppeds, I'm guessing you rifle has a 26" barrell.

[D.Camilleri]

I have to tell you that when I first got my 338 rum I tried H-1000 and couldn't get over 3100 with a 100 grain charge. Several years went by and I started hearing of much higher velocities so I tried another batch. Bingo, the burn rate changed! 100 grains is way too hot in my gun now and 98 is still pretty warm. I have a 27 3/8 broughton 5C barrel with a blueprinted action, so your results could vary. I can get about the same velocity with reloader 25, but 25 is temp sensitive, so as it gets colder velocity goes down.

[blackaj]

Wow that is kinda scary! I guess that's why it's important to work up to a max load. I'll give the H-1000 a try for sure.

[Old teacher]

I am sure others will add to what I am going to tell you, but I will tell you the typical things that I always look for that indicate high pressures. You have recognized one, and that is the extractor mark on the head case. Other things to watch for are problems with the primer itself. Cratered primers indicate high pressures, and , although it is difficult to see it very well I the picture, it does appear that you have a little of that going on. Flattened primers also indicate high pressures. Fired primers should look just like an unfired ones, except they have a dent from the firing pin. Also watch for primers with holes in the bottom. Measure your cases after each firing and record how much they are lengthening. They will always grow a little, but excessive lengthening indicates high pressures. You should not have to trim cases after every firing. Check for signs of head separation. RCBS makes a tool called a "Case Master Concentricity Gaging Tool" that is very useful in a number of ways, including checking for case head separation before the problem is apparent from the outside. It also checks for case neck and bullet run-out and a number of other things. You can get one from RCBS or Midway for about $120. Check for cracks in the case neck, and any time the bolt is hard to open, pressures are too high. Those are the typical things to look for. Maybe other members will add some others.