While hanging out in Reddit the other day, I came across a celebratory post for achieving a hit at over a mile. This is a pretty big deal and that’s a really long shot. I congratulated the poster and mentioned that making a hit a mile with the .338 Lapua Magnum (.338 LM), which I’ve taken out to 1065 yards, is on my bucket list. The poster responded noting he didn’t know much about .338 LM and bet it would put his 6.5mm Creedmoor (6.5 CM) to shame.
Realizing that I hunt with a 6.5 CM, it got me wondering about the differences between the 6.5 CM and the .338 LM. As so here we are.
These are two completely different cartridges but both are known for being able to go the distance. Because they are so different, this isn’t going to be an apples to apples comparison. Regardless, I think it will be fun to compare them. For this comparison, I will look at the advertised ballistics of Hornady’s Match product line with both cartridges using an ELD Match projectile.
|6.5mm Creedmoor||.338 Lapua Magnum|
|Bullet||140 grain ELD Match||285 grain ELD Match|
|Ballistic coefficient||.646 (G1)|
|Muzzle velocity||2710 fps||2745 fps|
|Muzzle energy||2283 ft/lb||4768 ft/lb|
The advertised ballistics should make the differences between the two cartridges should be obvious. Both of these projectiles have a fairly similar advertised muzzle velocity with the .338 LM being 35 fps (or about 1.3%) faster than the 6.5 CM. Both of these projectiles have really good ballistic coefficients, but the .338 LM is significantly better which means its trajectory will be flatter and experience less wind drift than the 6.5 CM. The .338 LM projectile is also about twice as heavy as the 6.5 CM projectile which translates into about double the muzzle energy and much more recoil.
The following table compares the velocity of the projectiles at various distances:
|Distance||6.5mm Creedmoor||.338 Lapua Magnum|
|500 yards||2059 fps||2198 fps|
|1000 yards||1516 fps||1765 fps|
|1500 yards||1135 fps||1332 fps|
|1750 yards||1026 fps||1185 fps|
Velocity is important to keep in mind when shooting at extended distances with supersonic projectiles. Once the velocity has decreased enough to begin crossing the transonic barrier (meaning when the projectile goes from being supersonic to subsonic) most projectiles will begin to tumble which results in a significant loss of accuracy. Which for precision shooting, this is what will determine the cartridges effective range.
I’ve always heard to use 1200 fps as a rule of thumb for the transonic barrier. While a bullet has a velocity greater than that it is supersonic and stable. When a bullet’s velocity is below that it’s entering the transonic barrier and begins to destabilize. However, depending on atmospheric conditions and projectile design the bullet may remain stable enough to remain accurate as it approaches 1100 fps.
Using the advertised ballistic data in a ballistic calculator we can see that the approximate effective range the 6.5 CM is about 1500 yards compared to the approximate effective range of the .338 LM of about 1750 yards. There are a few things one can do to push these ranges out a bit further. For example, one could use longer barrels in order to increase the initial muzzle velocities. Another thing would be to develop custom hand loads that are hotter (increased pressure) than these factory loads.
Okay. That’s cool. But how much drop will these projectiles experience at the same extended distances?
|Drop||6.5mm Creedmoor||.338 Lapua Magnum|
The drop data confirms that .338 LM has a flatter trajectory than the 6.5 CM. At 500 yards, the difference in drop between the two projectiles is about 3.9″ (0.7 MOA or 0.2 MILS) which is not a huge difference. However at 1500 yards, the difference in drop is now 157.6″ (10 MOA or 2.9 MILS). That’s pretty significant.
The reason this matters is because at 1500 yards equipment selection becomes very important. At this distance, the 6.5 CM will require a come up adjustment of 61.8 MOA or 18 MILS. To the best of my knowledge this adjustment will exceed the mechanical adjustment limits of many scopes. This means one will either need to acquire a very high end scope, a scope base with an elevation adjustment, or both. Since the .338 LM experiences less drop, one can get away with less specialized optics at the similar distances.
Let’s look at wind drift.
|Drift||6.5mm Creedmoor||.338 Lapua Magnum|
Similar to the data on drop, the drift data confirms the .388 LM is less susceptible to wind drift that the 6.5 CM. This also implies the .338 LM can be a little more forgiving in requiring more specialized equipment at similar distances.
However, reading wind is a skill that takes time to develop and in my opinion is more of an art than a science. Perhaps this is due to my limited experience with long distance shooting, that I hold the opinion that most misses at extended distances are a result of bad wind calls. Sure one can have a bad distance call as well, but at least there are tools like laser range finders that when used properly take the guess work out of the equation. To me this means, that a projectile that is less susceptible to wind drift will be a little more forgiving to wind call estimates.
After writing all of this, it might seem that I am saying that the .338 LM is a better choice for long distance shooting. After all, it has a longer effective range, it’s got a flatter trajectory, and is less susceptible to wind drift. All else being equal, I think it would be correct to declare the .388 LM as the better choice. Unfortunately, there are some additional things to consider.
Compared to the 6.5 CM, the .338 LM has significant more recoil. This recoil may be a non-starter for some folks. This recoil also means that follow up shots will generally be a slower as it will take a little longer to get the crosshairs back on target after a shot.
Other drawbacks to the .338 LM include ammunition availability and price. Perhaps availability is different in different locales. However, my experience has been that I can find a significantly larger selection of quality match grade 6.5 CM ammunition and components in just about any store that sells ammunition. Selection for .338 LM is limited at best and non-existent at times. In terms of price, just compare the typical retail price of about $35 for a 20 round box of 6.5 CM Horandy Match versus the typical retail price of $100 for a 20 round box of .338 LM Hornady Match.
So which one is better? It really comes down to the application and the size of the wallet. If the application is hitting targets consistently at a distance of one mile, then my choice is the .338 LM. If the application is long distance shooting at targets at 1250 yards or less, my wallet is going to pick the 6.5 CM more often than not.