Moving from 338 to 7mm.

[aramarine6]

The time has come to move from my beloved 338 RUM to a 7mm mag. The 338 RUM used to be the "poor mans lapua." But now that brass is nearly impossibly to find and Nosler charges $65 for 20 pieces of brass. I have made the decision to go with a bartlein barrel, M40 contour, finished at 26 inches. My biggest hurdle is figuring out which is the best twist rate for this build. I'm currently waiting on Bartlein's opinion on twist but figured I'd pick your guys brains. The lightest bullet weight I'll be shooting is the 162 Amax and the heaviest being the 180 Bergers. Your opinions are greatly appreciated.

 

[MudRunner2005]

If you don't ever plan on shooting the new 195's, then a standard 1:9 twist for the 160-180's should be fine.

 

[ohiohunter]

Curious why such a big down size? Just brass availability and cost?

 

[PGJPJ]

Some of the mono's, 168 grn Barns LRX for example, require a 1:8. Also, who knows, you might want to play with the 195 Bergers some day.

Why not the 1:8? But definitely no slower then 1:9

 

[aramarine6]

Brass availability is a major issue right now. I used to be able to find it everywhere... even during the great brass/powder shortage. My Remington brass is toasted after 4 loadings. Primers literally fall out of the pockets. Which is clearly a problem when brass can't be found and will likely never improve. Remington is limiting brass production to once a year and they only make 2 or 3 rifles in the 338 RUM. Remington has a bad habit of producing a cartridge and then not supporting it by offering few if any rifles in that cartridge. Even loaded ammo is hard to find and most of it is produced by Nosler. With Remington only producing 1 loading which is 250 swift A frame. Great if I was slaying Elk every year... but I use this rifle specifically for long range target shooting. In the end going to a 7mm mag I'll save money on reloading costs, cut my recoil down by half. Which in turn I can get rid of my hideous muzzle brake. Not to mention a lighter weight system should I decide to take it hunting. Yes the barrel will burn up faster but this is something I can live with given the advantages. I'd rather do more shooting than complaining

 

[MudRunner2005]

Brass availability is a major issue right now. I used to be able to find it everywhere... even during the great brass/powder shortage. My Remington brass is toasted after 4 loadings. Primers literally fall out of the pockets. Which is clearly a problem when brass can't be found and will likely never improve. Remington is limiting brass production to once a year and they only make 2 or 3 rifles in the 338 RUM. Remington has a bad habit of producing a cartridge and then not supporting it by offering few if any rifles in that cartridge. Even loaded ammo is hard to find and most of it is produced by Nosler. With Remington only producing 1 loading which is 250 swift A frame. Great if I was slaying Elk every year... but I use this rifle specifically for long range target shooting. In the end going to a 7mm mag I'll save money on reloading costs, cut my recoil down by half. Which in turn I can get rid of my hideous muzzle brake. Not to mention a lighter weight system should I decide to take it hunting. Yes the barrel will burn up faster but this is something I can live with given the advantages. I'd rather do more shooting than complaining

Welome to the dark side. Once you go 7mm, it's really hard to ever find a reason to stray. There is a 7mm cartridge for every need from the 7mm TCU all the way up to the 7mm Allen Mag. And with the introduction of the new Berger 195's, the big 7's will hit hard, and shoot flatter than the big 30's or .338's.

Remington has done that alot in the past. One of their biggest screw-ups was not supporting the 7mm STW properly. That turned out to be a big one they dropped the ball on.

 

[Lefty7mmstw]

This is nearly the opposite direction of where I'm going with my rifles. I just picked up a remmy 700lr in 300rum... I plan on turning my existing 300rum ( a m700 bdl lh) into either an edge or 338rum. The build will likely be done next summer if/when finances allow. Properly loaded, the brass will last ten cycles or better, so 100 rounds of brass will last a good while.

I did build a lh m700 in 7stw this year, but that had as much to do with component inventory as cartridge selection. I really like my big 7mm's, but I don't know if I'll ever go as small as a 7rem for a belted cartridge again unless it is a rifle for my kids. I really don't see the reason to use a belted (7rem) for the little bit of gain you get over the 270/280 rifles.

Good luck to you on your 7rem; they work, but I'd look at a bigger 7mm like the 7x300 first. I've had a few 7rems, and I don't currently own one.

As far as twist, I would only look at 8" twist... The lighter bullets, say 140 and heavier, will shoot just fine on a 8" twist, but you will not spin your pills fast enough if you ever decide to go with a heavyweight if you go with a 9" or slower. I put a 8" twist shilen select match on my 7mmstw and she loves the 195 berger and 140 nos ab.

 

[Rich Coyle]

tag

 

[bigngreen]

Interesting thread, I convert a number of Rem 7 mags every year to 300 mags and 338 RUM's, never had a guy yet want to go back, never even had a request to build a 7 mag!!

 

[Broz]

Do your own research and choose wisely. As for me I am done with 7's as of a few weeks ago. I have used them in many shapes and forms for many years. Have taken many elk with the 195's from the 7-300 this year and an antelope. Many elk in the past with 168's and 180's in fragmenting and controlled expansion offerings. So far this year I have been there, (along side the rifles) and for the field dressing, of close to 40 elk. Most taken with my rifles. 7mm's, 300's and .338's. I have seen over and over what happens when the shot placement is a little off. I now know for myself what I truly believe to be truth in this matter. Not internet hype, or jabber from fans from any given caliber, but what I have seen repeatedly for years and proven to myself for the last time this season. When similar heavy for caliber bullets are used, 30 cals kill better and quicker than 7's, and a good 338 will trump them both in ballistics and terminal performance.

Ballistic performance boils down to BC and velocity. Bigger higher BC bullets propelled at similar velocities will always end up with less drift, retain more velocity and arrive with more energy at some point. This is why the big 338's will trump 7's and 30's when all are loaded in the case to make them excel, and why bigger will go farther and do more work.

My medium bore magnum is now exclusively my 300 win with a 215 Berger at 3035 fps. It has shown me over and over how it will kill better than the 7's when point of impact is a little off. If I want to kill quicker and go farther than the 300 win. I will use my 338 Terminator.

May not be what some people want to hear. But this is 100% my opinion with 100's of elk kills in the last several seasons and documented results.

As for twist, I have used 9.25 to 1, many 9 to 1's, some 8.5 to 1's and some 8 to 1's in the 7's. I recommend you go with the 8 to 1. It will get you all the BC your bullets have to offer and keep it for farther.

I only wish I could show you for yourself what my eyes have seen this season with the 40 elk we have killed so far. Taking a 30 and a 338 to kill some more tomorrow if the weather permits.

Good luck in with whatever you choose.

Jeff

 

[aramarine6]

Thanks for the info. I love my 338 and shooting it at a16 inch plate at 1000 yards has almost become boring.... Almost. I wouldn't be getting rid of it if I could find brass. If I knew RUM brass would become so scarce I would built a lapua.

 

[Broz]

Thanks for the info. I love my 338 and shooting it at a16 inch plate at 1000 yards has almost become boring.... Almost. I wouldn't be getting rid of it if I could find brass. If I knew RUM brass would become so scarce I would built a lapua.

So you need some 338 RUM brass, want me to check around and see what I can find among friends? How much would you need?

Jeff

 

[aramarine6]

50 pieces new will get me through till spring or 100 pieces once fired will work.

 

[450hunter]

Can 338 RUM brass be made/fire formed from another case