The recent post comparing the .338 Lapua Magnum (.338 LM) to the 6.5mm Creedmoor (6.5 CM) generated some discussion and some questions. One question, which came in via Twitter, asked somebody asking how the .300 Winchester Magnum (.300 WinMag) fits in?
I’ll attempt to answer that. But, please keep in mind that I have no experience with the .300 WinMag whatsoever.
I’m going to reuse the data from the .338 LM vs 6.5 CM post and add the .300 WinMag to it. First up is the advertised ballistic information from the Hornady Match product line up.
| Advertised Ballistics | 6.5mm Creedmoor | .300 Winchester Magnum | .338 Lapua Magnum |
|---|---|---|---|
| Bullet | 140 grain ELD Match | 178 grain ELD Match | 285 grain ELD Match |
| Secional density | .287 | .268 | .356 |
| Ballistic coefficient | .646 (G1) .326 (G7) | .547 (G1) .275 (G7) | .789 (G1) .394 (G7) |
| Muzzle velocity | 2710 fps | 2960 fps | 2745 fps |
| Muzzle energy | 2283 ft/lb | 3462 ft/lb | 4768 ft/lb |
I wasn’t surprised to see that the ballistic coefficient (BC) of .300 WinMag was lower than both the 6.5 CM and the .338 LM. This is typical of fatter .308 caliber projectiles used in the .300 WinMag cartridge tend to be about the same overall length as the skinnier .264 caliber projectiles used in the 6.5 CM. This lower BC implies the projectile from the .300 WinMag will experience drop and wind drift at a faster rate than the .338 LM and the 6.5 CM.
However, the initial muzzle velocity of the .300 WinMag is significantly higher than the other two. This begs the question, will the lower BC really matter in terms of comparing the effective range of the .300 WinMag against the other two cartridges? It’s time to use a ballistic calculator and figure out the velocity, drop and drift at various distances.
The following table compares the velocity of the projectiles at various distances:
| Velocity | 6.5mm Creedmoor | .300 Winchester Magnum | .338 Lapua Magnum |
|---|---|---|---|
| 500 yards | 2059 fps | 2159 fps | 2198 fps |
| 1000 yards | 1516 fps | 1508 fps | 1765 fps |
| 1500 yards | 1135 fps | 1086 fps | 1332 fps |
| 1750 yards | 1026 fps | 980 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 starts transitioning from being supersonic to subsonic) most projectiles will begin to destabilize and eventually tumble which results in a significant loss of accuracy. Which for precision shooting, this is what will determine the cartridge’s effective range. This roughly happens when a cartridge slows down under 1200 feet per second (fps).
To be honest, I was quite a bit surprised by these numbers. I was expecting the .300 WinMag to have an effective range somewhere between the 6.5 CM and the .338 LM due to it being a magnum cartridge. However, it looks like the lower BC really made a difference. The data shows that by the 1000 yard mark the .300 WinMag projectile is traveling at a lower velocity than both the projectiles from the 6.5 CM and the .338 LM. The projectile from the .300 WinMag begins going transonic at around 1350 yards whereas the projectiles from the 6.5 CM and the .338 LM begin going transonic at around the 1400 yard mark and the 1750 yard mark respectively.
So in terms of effective range for long distance shooting, the .300 WinMag is edged out by the 6.5 CM.
Okay. That’s cool. But how much drop will these projectiles experience at the same extended distances?
| Drop | 6.5mm Creedmoor | .300 Winchester Magnum | .338 Lapua Magnum |
|---|---|---|---|
| 500 yards | 53.1″ | 45.2″ | 49.2″ |
| 1000 yards | 316.8″ | 284.1″ | 280.7″ |
| 1500 yards | 970.6″ | 921″ | 813″ |
| 1750 yards | 1531.3″ | 1492.5″ | 1249.6″ |
The drop data confirms that .300 WinMag has a flatter trajectory than the 6.5 CM, but not quite as flat as the .338 LM at extended distances beyond 500 yards. Up to just beyond the 500 yard mark, the .300 WinMag has the flattest trajectory of the group. This seems like an expected result as the .300 WinMag has the fastest projectile of the bunch from the muzzle and it also has the projectile that slows down the fastest due to its lower BC.
One might be surprised that even at extended distances the .300 WinMag is flatter than the 6.5 CM all the way out to the 1750 yard mark (basically the mile mark). This is also a result of the .300 WinMag’s greater muzzle velocity which results in a shorter flight time out to the 1750 yard mark. However, the difference in drop between the two at that distance is not really relevant since that distance is outside their effective range.
Let’s look at wind drift.
| Drift | 6.5mm Creedmoor | .300 Winchester Magnum | .338 Lapua Magnum |
|---|---|---|---|
| 500 yards | 14″ | 15.3″ | 11″ |
| 1000 yards | 67″ | 72.8″ | 51″ |
| 1500 yards | 173″ | 193.3″ | 130″ |
| 1750 yards | 247″ | 277.3″ | 187″ |
The wind drift data shows that the projectile from the .300 WinMag is the most susceptible to wind drift out of the bunch. This is a result of the .300 WinMag having the lowest BC out of the bunch. Furthermore, this implies the .300 WinMag will be the least forgiving of the three to errors in wind calls.
After writing all of this, it might seem that I am saying that the .300 WinMag isn’t a better choice for long distance shooting against the 6.5 CM or the .338 LM. After all, it has the shortest effective range, a middle of the road trajectory, and is most susceptible to wind drift. But that’s not quite what I think.
I think it’s fair to say that on a windy day, the .300 WinMag will be the most difficult cartridge of the three to get accurate hits with due to its susceptibility to wind drift. On a day with mild or no winds the .300 WinMag can basically do what the 6.5 CM can do, perhaps even a little better due to the .300 WinMag’s flatter trajectory. On the other hand, the .300 WinMag will provide the shooter with more recoil to deal with.
I also think it’s fair to say that neither the 6.5 CM nor the .300 WinMag would be a better choice over the .338 LM for mile long shots.
Not an accurate statement, like most comparisons it all depends on your choice of bullet, twist rate in order to fire a heaver bullet etc. The Lapua .308 (300WM) in 220gr has a BC of 0.647
`The 6.5CM is an awesome calibre and its on my wish list due to accuracy at 1000yds and low recoil however. If you want to shoot a mile, the 6.5CM is probably too light. The WM would be a better choice.
That’s a fair point and unfortunately taking the time to account for all the possible variations of loads and equipment options it would be near impossible to offer any comparisons. You may have missed the initial comparison post where I mentioned that selections would be limited to the advertised ballistic information from the same factory product line using the most common projectile weights in order to have a relatively consistent basis for comparison.
Could a hand loaded 300WM with an odd ball projectile and custom powder charge tuned to a specific custom built rifle go further than a common factory 338LM out of a production rifle? I’d have to do the math, but I suspect that is extremely probable. The reverse is also likely true and I would assume even more so. I also strongly suspect that similar comparison results could be made using less common factory load variants.
As such, I’d argue the statements made in the comparison are accurate given the used comparison parameters unless there is a mistake in the calculations which I have been unable to find.
300 win. Mag disadvantage because I wanted the 190 grain bullet for comparison which would have 3000 muzzle velocity, more energy and less wind deflection. And a 26 inch barrel. I spent 15 years in Montana hunting and the 190 grain bullet is a better choice!
That certainly sounds like a fantastic preferred choice based on your experience and set up. Without knowing the details of the projectile, such as the BC, I am unable to agree or disagree with the claim that it’s a better choice. That said, it is certainly plausible a load and rifle combination for the 300WM could perform better or go further than one of the common factory loads used in the comparison. It is also entirely plausible that a load and rifle combination with one of the other compared cartridges might perform better or go further than your preferred load. There are simply too many variables to make an exhaustive comparison.