The 338’s: RUM, Lapua, & Edge

The 338’s: RUM, Lapua, and Edge
by Lucas Beitner

There is a great deal of interest in .338″ caliber cartridges for long range shooting. This is specifically due to high BC mass produced bullets available. While it takes a great deal of powder to push a 250gr to 300gr bullet at acceptable velocities for long range shooting, the performance has trumped the cost in the minds of many shooters (not to mention military and law enforcement world-wide). Recently, the most popular long range 338’s are the 338 Remington Ultra Mag, 338 Lapua mag, and 338 Edge. The first two are self explanatory, the Edge is a 338×300 Remington Ultra Mag. It is most commonly referred to as the 338″Edge” due to Shawn Carlock of Defensive Edge who is the biggest proponent of the cartridge and has, by far, the most experience with it. There are some other 338’s for long range, but I’ll mostly focus one these three for the sake of keeping this brief. These cartridges can be used in factory long actions and make a repeater. Even when using long, high BC bullets, like the 300gr SMK!

One common misconception is that these cartridges are end all, be all, 1000yd lasers. While the 1000yd performance is excellent, there are much more efficient ways of getting equal and in some cases better ballistic performance at 1000yds and less. For example you could fire a 168gr Berger VLD from a 7mm mag at 3100fps and have an expected drop of 22.25 MOA and drift of 5.25 MOA for a 10mph cross-wind at 1000yds. A 338 Lapua mag firing a 250gr Scenar at 2960 would have a drop of 24.25 MOA and 5.25 MOA windage for the same range/conditions. A Lapua mag firing a 300gr SMK at 2850fps would have a drop of 25 MOA and 4.75 MOA windage for the same range/conditions. If you want to see how these 338’s stack up to other cartridges, run the numbers through a ballistic calculator. For those who take large game at or near 1000yds the energy provided by these cartridges is ideal. Where the 338’s really shine  ballistically is well beyond the 1000yd mark. They have been used effectively and with accuracy out to 1 mile (1760yds) and beyond. Two of the major obstacles to shooting at extreme range are going sub-sonic (or even trans-sonic) and wind drift. A major part of the solution to both of these, is a higher than usual BC’s. Let’s consider some of the long range bullets available for the 338’s…

250gr Sierra Match king BC: .587 (above 2150fps) .606 (between 2149 and 1700fps)

250gr Lapua Lock Base BC: .662

250gr Lapua Scenar BC: .675

300gr Sierra Match king BC: .768

The popularity of this caliber will only insure that more high BC bullets will be developed in the future. Berger will be releasing two new bullets for the .338″, one of which is rumored to weigh 300gr and have a BC of around .855!

There is great debate about the velocities these cartridges can produce in relation to each other. I do not have the resources available to build and compare each of these cartridges with identical components so we’re left to speculate on what info is available. My Sierra Reloading Manual uses a 26″ test barrel for both the 338 RUM and the 338 Lapua. It gives essentially identical maximum velocities for the bullets in question, although the RUM was reaching them with a higher percentage of the powders tested. This seems counter intuitive because the capacities of these cartridges are virtually the same and the Lapua is rated at a maximum pressure of 69,000 psi, while the RUM is rated at a maximum of 64,500 psi (Vihta Vuori Reloading manual). I can’t confirm what pressures Sierra used to test these cartridges, but the data is scientifically acquired. The respective velocities of factory loaded ammo for these two cartridges would suggest that the Lapua has the velocity advantage. There is much debate in internet forums of how these cartridges stack up. The most popular consensus (from what I’ve gathered) is the 338 Edge is the fastest followed by the Lapua mag, with the 338 RUM not too far behind. I would argue that this is the most sensible conclusion since it follows the general capacity/pressure model (please do not take this to mean I view forum opinions as scientific data). The debate is somewhat irrelevant, since we’re talking about a spread of less than 100fps between them. The barrel’s design and length could possibly have a greater impact of MV than the cartridge itself. If you’re like me, the fastest load you test for a particular cartridge may not be the one you use. Other factors weigh in like accuracy (low ES and SD) as well as temperature sensitivity etc. It would be difficult to speculate what cartridge would provide the highest velocity while remaining “accurate”.

Many  wonder about how long a barrel should be for these cartridges. From what I can gather 28″-30″ is about optimal. This gives you the MV’s you expect and allows you to keep the weight manageable. Some have used up to 34″ barrels and are claim higher MV’s and better ballistic performance. I’ve heard that going from 28″ to 30″ only nets and extra 50fps. It may not seem like much for the weight of two inches of barrel. For some it may be worth it. Depending on how far you want to shoot your rifle, an extra 50fps could be just what you need. If 28″ barrels and the weight that comes with them is unattractive to you, I’d recommend looking into other cartridges (or re-evaluate your long range goals). There is no point in wasting powder in the form of muzzle blast. These are large cartridges that use slow burning powders and require long barrels.

The biggest difference in my opinion between these cartridges is reloading cost. They’ll use around the same amount of powder, and the bullets are the same, but the brass is another story. Brass for the Lapua is commonly found for around $195 for 100pc. The 338 RUM, and 338 Edge (wich uses 300 RUM brass) can be had for around $80 for 100pc. This is a big difference in reloading cost, although a straight across comparison would probably not be fair to the Lapua. It’s quite likely that the Lapua brand brass (one of only two brands currently available for the 338 Lapua) would last a couple more firings compared to the others. It’s also notable that to build a rifle in 338 lapua a standard magnum bolt face would not work, requiring a little more work by your gun smith (my smith only charged me around $30 for this, but your mileage may vary). The 338 Edge definitely gives the most bang for your buck. Some claim the Lapua is more accurate. If this has any merritt, it’s likely due to higher brass quality available for the Lapua. If one does a quick search you’ll quickly find excellent long range accuracy can be had by the RUM and Edge. It is my opinion that the smith you select to build your rifle, will by far have the greatest influence of the accuracy potential. That being said, I personally use Lapua brass when it’s available for a cartridge I’m loading.

Some other 338 cartridges that may catch your attention and deserve your consideration include: 338×378 Wby mag, 338 Kahn, 338×416 Rigby Improved, 338 Snipe Tac, 338 Allen Magnum, 338 Titan, and others. Any of these will ballistically outperform the RUM, Lapua, and Edge.


  • http://www.facebook.com/people/Sean-Pomerinke/1584012465 Sean Pomerinke

    I would agree with Lucas about accuracy over speed. I can load up to 97gr of powder but I keep it at about 93 because that is my most accurate load. If you are punching through the same bullet hole I would not change a thing and at 2,850 fps that is not slow ether. I am able to load to speeds over 3,100 fps but I want to neck up to a 338 and the most I will be able to get is probably about 2,900 and that’s the most.

  • timxlt

    is there any advantage of tradeing my 338 rum for a 30-378 wby?

  • http://http://http:// Freddie Hunt

    timxit. it depends on what you’re using it for. for long range id go with the 338 but if you’re only shooting out to 300yds max then go for the 30-378 because its so much flatter. i think if your not shooting excessive long range then a 300 win or wby is perfect for anything up to buffalo. if you want a big bore rifle for brown bear, buff, rhino, etc then i recomend u get a .416 or bigger.
    Have fun!

  • jeremy

    how many times can you reload the 338 rum brass before you see signs of separation or is just a good safe time to discard them

  • http://longrangeshooter.com Sean

    That depends on a lot of factors
    :Quality of brass
    :How much powder is used
    :Are you Annealing your brass
    :Neck re-sized or full length
    :Seating depth

    There is really no magic number so you will have to feel it out. In “most” cases the neck will split first. Just make sure you keep an eye out for a frost line.

  • http://http://http:// rossi

    I posted here last on oct 9 about my 338 thougts I am collecting parts I have reamer and die set from defesive edge tactical stock from coate 30 inch heavy varmint barrel from lawton stainless remington action i will have the action trued and sleve the bolt
    and jewell trigger 20 moa farrel
    scope base iam not sure about wich scope to use any thougts ?

  • Larry Smith

    I am having trouble finding a rifle chambered for the .338 RUM. Any suggestions? I have, however, been able to find two chambered for the .338 Lapua. One is made by Savage the other is Remington. Which is better?

  • Jeff Dempsey

    The 338/300 Ultra Mag is the ultimate big game gun. In October 2000 took a 6×6 bull @ 597 yds, a bear @ 853 using 250 gr. Sierra game king. Fitted with 30″ PacNor 3 groove barrel. Good for North America’s larger game. There is a lot of loading data on them now, in 1999 there wasn’t much.


  • Michael L Hauschild

    Once in my youth, and contemplating a Safari which did not come about, I purchased a factory 378 Weatherby. I acquired the firearm to acclimatize myself to the recoil and as the plains game segment of the battery.
    That was an amazing firearm; with an H870 (no pressure signs load) it would chronograph an honest 3100 fps with the 300 grain Sierra. While the firearm was ordered without a muzzle brake; about twenty rounds later that mistake was remedied. Interesting enough the muzzle brake added an average of fifteen fps to the velocity of the three hundred’s; the two seventies stayed the same. I did load some 235’s to see just how fast a bullet would go (over 3400 fps) and one of my friends actually shot his first deer with that bullet/load (not a good idea).
    All this occurred several decades ago and I must say that firearm taught me marksmanship, concentration, and respect for those who take the time to achieve the ability to humanly harvest game at great distance. Distance is of course a relative term. While I have also spent a considerable amount of time pursuing helmet perspective targets and eroded to random impact numerous Hart, Krieger, and Douglas barrels this phase of the rifle mystique is just being attempted.
    I have never strayed far from the premise that “If you can shoot something big, you can shoot anything.” My current battery includes a 416 Remington (7.5 lbs) and a 577 Nitro (fourteen pounds). Our silhouette range conducts cowboy silhouette matches and we have “side matches.” That 577 actually won (I just held it) a match. 1050 fps, 750 grain cast bullet, 70% density Trail Boss.
    Which brings me to the point of the 338 bore and learning the nuances of shooting great distances.
    I have a single shot Whitworth 98 (no floor plate cut, solid receiver) it came to being as a 458 Magnum pistol, more as a novelty but as the 378 it was spectacularly accurate with cast bullets. It is now getting a new 338 bore thirty inch tube in 338-375 Ruger. I plan to shoot this firearm hundreds and hundreds of times. By the time the four molds for that bore are wrung out the only wear and tear will be on the tires of the truck traveling to our 600 yard range.
    Many of us do not have the Rocky mountains as a backstop, nor do we have several miles of measured range. Several thousand rounds from now while you guys are on the phone with your banker, your gunsmith and some three groove pipe manufacturer my barrel will still need a couple of thousand more rounds to finally settle in and start to shine up a bit. This commercial 98 reincarnation will always have the potential to maximize without the fleeting window of minute of angle a steady diet of compressed loads sub 100 burning rate produces.
    To possess a tool that delivers projectiles at a mile is to possess a tool that will deliver a cast bullet under an inch at two hundred meters. Most people do not take advantage of this simply because casting bullets for accuracy is as skillful and learned art as the technicians’ gunsmithing that creates these linear lasers. All things are to scale; marksmanship is possible at ten meters, or 1500 meters. It is also nice to realize that firearms do not have to wear out as fast as the brass. Trail Boss, 5744, and 4759 are not dirty words.

  • Russell

    I have ben working up a load for a custom .338 win mag with berger 250 GR and Hornady cases bullets seated out just in neck . the hornady cases becus of to much preshur i haft to back of around 200 ft from my loads with win cases and 250 GR smk eny ideas other than soft cases

  • Master Flash

    lol! Looks like powder burns on you from your sidearm. (Sorry.)

  • Master Flash

    Oh, BTW: You have to look at the hi-res image to understand.

  • John Dawson

    Why not just stick with the .340 WBY?