Monthly Archives: May 2013

The Staying Power of the .308 Winchester

There has been no shortage of opinions offered as to why the .308 Winchester just won’t pick up its marbles and go home. The onslaught of 6.5’s into long range work has been going on for a while now. The .260 Remington began making inroads against the .308’s popularity in sniper type comps some years ago. And now the 6.5 Creedmore and the 6.5×47 Lapua are gaining popularity–though they’re probably doing more damage to the .260 rem’s numbers than to what’s left of the .308 out there.

But what is “left of” the .308’s popularity is, when counted, quite a lot. I continue to see mostly .308’s coming to our shooting courses and long range comps, and I’m not so much thinking that trend is going to change anytime soon if ever.

Is it the “military effect” that keeps the .308 so popular when there are presumably so many “better” choices out there for long range work? This has been alleged, and to some extent, it’s probably true; the military has stayed primarily with the .308 Winchester cartridge (hair splitters stand down, I know it’s the 7.62×51) for their sniper rifles, choosing not to go the way of the Swedes, so to speak, by choosing anything in the 6.5 family of cartridges.

But I don’t think this “military effect” is the real reason for the .308’s continued popularity–rather I think the true reasons for the cartridge’s continued success will help to explain just why our military continues to use the .308. But before we get to those reasons, let’s look at a few of the reasons folks are choosing the 6.5’s and even 6mm’s over the .308 for long range work.

Wind drift. The biggie. You see a lot of comparisons between a 168 grain match bullet from a .308 launched at 2600 fps and a 6.5 mm 140 grain bullet launched at 2650 to even 2700 fps. Setting aside the fact that the 168 grain match bullet would be at or near subsonic at 1000 yards with an MV of 2600 fps, ballistic programs show it will drift just over a minute of angle in a 1 mph wind at 1000 yards. But the 6.5mm 140 grain bullet will drift about 30 percent less than that, with a realistic MV of 2650 fps. Push the 6.5mm 140 to 2750 fps and you can increase that drift advantage to 35 percent or so.

The power factor. Some of us .308 aficionados have tried to point out the 30 caliber’s weight and energy advantage over the typical 6.5mm at long range. However, charts contrived and available around the ‘net will show 140’s launched at 2750 fps turning in mid 600’s for foot pounds of energy at 1000 yards–and a 175 grain 30 caliber Matchking launched at 2650 fps turning in about 25 foot pounds less at that same range.

But if you want to go down the road of finagling numbers in ballistic charts we can… If you want a power advantage for the .308 it’s a simple matter to give it a 208 AMAX at an easy 2525 fps for a stunning 950 foot pounds of energy at 1000 yards. Game over, big time. And it drifts the same as the 140 grain 6.5mm at that range as well.

“Well I can get my 6.5mm 140’s to 2850 fps.”

And I can get the 208 AMAX’s to 2600 fps. You can run those numbers on your own time, but suffice it to say that you’ll need 6.5-284 power to get close to the drift numbers of the thirty caliber 208 AMAX with a 2600 fps push.

Recoil. Recoil control is indeed part of the accuracy equation (a too often forgotten part, I’d say). And the lighter bullets from the 260’s will get you an advantage in this department over the .308 shooting bullets fast enough and heavy enough to hang with the 6.5’s. We saw this when the 6.5/284 really began to unseat the 300WM in long range comps. Not that the 6.5/284 was any more inherently accurate than the 300WM–I don’t believe it is–but it recoils less, and given the same ballistic properties for wind drift, the accuracy advantage will go to 6.5/284–unless the magnum shooter has found a way by weight of the rifle and/or the addition of a muzzle brake to get the 300WM’s recoil down. Here again, though… run the numbers and look at the power factor downrange. If power matters, recoil will be a necessary evil to be dealt with–and it can be managed through various means.

Trajectory. Here is where the flatter shooting 6.5 and 6mm cartridges are getting the advantage over the .308’s heavier bullets, flying those “rainbow” trajectories. In a situation where you’re working on a target of unknown distance and you’re estimating range either by reticle subtension or just “eyeballing” it, the flatter shooting the cartridge, the more likely you’re going to get a hit. And to me, this is the best case for going to the lighter, faster bullet over the .308–if you’re looking for a reason, that is.

I said all of the above primarily to just get those arguments off the table, and hopefully deflect the rhetoric that often flies in a conversation about 30 caliber versus 26. Now, if you’re still with me, I’ll get to the reason that I believe the .308 really continues to hang on to the lion’s share of popularity in the long range practical arena. It is “user friendly.”

By the way, I’m not saying that the .308 is necessarily going to show up more often than 6.5’s at the competitions or matches that you may personally be familiar with–I’m simply saying that based on the sales numbers, far more people are buying .308s than are buying these smaller calibers. Esoteric shooting events are not always a good indicator of what’s really going on in the market at large.

For those of us who handload enough to make the claim with a straight face that we’ve graduated from the rank of novice, we’ll admit that while truncated versions of the .308 Winchester (the .243 Win and the .260 Rem) can be a bit fussy about what they’ll shoot and what they’ll splatter, the .308 is not picky. Did you ever go to lunch with a picky eater? First, they can’t decide where they want to go… then they can’t decide what they want off the menu… then they want to alter the dish in some manner aside from how it is typically served. And then they complain anyway.

But the .308 is not such a critter. It’ll “like” bullets from 125 grains all the way to 210 grains, and it’ll digest various powders with aplomb and decent accuracy. From 3031 to something as slow as IMR 4350–or even 4831, the .308 will deliver the goods. It is “easy to please” is what I’m saying, whereas the .243 and the .260 are both prone to being picky eaters (if we’ll be honest).

This leads us to the observation that the 308, like its 30-06 predecessor, seems to have wider accuracy nodes when compared to its sub caliber competitors.  This allows it to perform well over broader temperature swings than, say the .243 Winchester. I love my .243s, but the nodes just are not as spacious as the .308 nodes. Move the powder charge .3 grains and most .243 loads will show a notable negative effect, especially at long range. But .3 grains doesn’t seem to phase a good .308 recipe in most situations.

Yes, you can weigh every charge and that’s a good thing to do. But weather and atmospheric effects will move the center of the node as well, and unless you do what BR shooters do and tailor your load to the day and location, you could find your sub-caliber .308 based cartridge not shooting as well as it otherwise does. This is likely the reason that even temperature sensitive powders such as W748, RL15, and to a lesser extent IMR 4895 still do better than many would expect in cold and hot weather–in the .308 win cartridge, that is.

And so I think it is this “user friendliness” that allows ammo makers to make match grade sub MOA accurate cartridges for the .308 which can be relied upon to shoot tight from untold millions of different rifles. As I’ve said many times, “show me a .308 that won’t shoot lights out with Federal Gold Medal Match, and I’ll show you a rifle in need of a trip to the gunsmith.” Not so, however, with necked down versions of the cartridge. They’re going to be picky enough on an individual level that mass producing match grade ammo will be a harder task. It’ll be harder to get the recipe right, harder to keep the charge on the node, and harder to continue selling that ammo once 3/4’s of the population shooting that cartridge find that it won’t shoot as well as their handloads in their own rifles.

So let’s see if I’m right. In a dozen or two dozen years… if this little blurb somehow manages to last out there in the cyber world long enough to be found and referred back to, I’m betting the .308 will remain ensconced where it is now, not having been unseated by anything new, or anything better.

Dan Newberry

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Canted scope or canted rifle… (the difference)

This picture represents a canted rifle underneath a level scope. You’re looking at the buttstock of the rifle, and on through the scope. The orange circle is the approximate location of the bore of the rifle. The blue dots represent the fall of the shots as they go downrange; they fall with gravity along a line which is represented by the vertical crosshair in the scope.

What we must concern ourselves with to understand this issue is the scope and the bullet path. When you dial the scope’s erector to zero for windage, you are essentially aligning it with the bullet path–not the barrel!

So if a scope is mounted slightly canted, but held level, the bore of the canted rifle would only be off to the side a fraction of an inch (perhaps 1/16 to 1/8 inch) underneath. It would look something like this:

Is it important that the bore isn’t 100 percent underneath the scope’s vertical crosshair? Actually, no.

Think about it this way:

If you have the scope dialed to a perfect 100 yard zero with one particular load, and then you switch to another load, you’ll likely note that your windage zero will change. Has the scope moved? No. Has the barrel changed? No. Only the direction that the barrel is throwing the shots has changed. Barrels, by their very nature, throw shots here, there, and yonder. So you must dial the scope’s erector to follow the general path of the new load to get your zero. This may take the scope’s centerline well away from the boreline–but that’s not what’s important. Bullet path and boreline are two different things.

You see, the scope’s erector is never actually aligned with the bore of the rifle to begin with–it is aligned with the path of whatever bullets you are setting the zero for.

What I’m saying is that you can have a slightly canted scope, with the barrel underneath at, say, 5:30 and so long as the scope is held level, the shots will still fall parallel with the vertical crosshair.

In the top image, there is the ideal situation where the scope’s vertical crosshair perfectly disects the fall of the shots.

In the second image, the scope is mounted with a slight cant, but since the scope is being held level, this means that the rifle bore is off by a bit underneath it. It’s at 5:30 rather than 6 o’clock. Note how the shots fall just slightly to the right of the vertical crosshair. Groups forming downrange would probably never indicate that the 5:30 rifle cant even existed, as these shots would only be off to the right of the vertical crosshair a tiny fraction of an inch.

What if you layed the rifle on its side?

If you layed the rifle on its side (and mounted the scope upright, with the elevation turret up top),

…this would of course put the scope about 1.5 inches to the left of the bore. If you zeroed the scope for the shots to fall dead on at 100 yards then yes, you would have an angular relationship with bullet path and line of sight. You’d only be zeroed for 100 yards. From the rifle to the target, you’d begin with almost 1.5 inches of error, slowly correcting until you got to 100 yards, then beyond 100 yards your shots would deviate farther and farther from the windage zero you had at 100 yards.

However, if, as is shown in the drawing immediately above, you were to take into account that 1.5 inch difference with the “sideways rifle,” and you dialed the scope so that the shots fell 1.5 inches to the right of the crosshair intersection at 100 yards, these shots would stay only 1.5 inches right of the line of sight all the way downrange (wind factors and such notwithstanding).

In another possible scenario, you could simply take this sideways rifle and dial the windage zero to be correct at 1000 yards. Then, you’d be off a little less than 1.5 inches at 100 yards, and the bullet would begin “closing in” on the windage–and the closer the bullet got to 1000 yards, the more it would close the 1.5 inch gap. At 1000 yards, the bullet would cross the line of sight, then begin deviating in the opposite direction, and by 2000 yards, it would be about 1.5 inches to the other side. Obviously, this 1.5 inches would not be much of a factor at the longer ranges.

So, with the slightly cant-mounted (but held level) scope, you’re not going to be off anywhere near 1.5 inches all the way downrange. It’ll be more like 1/8″ or so–and wouldn’t even be noticed in a 1 MOA group size.

So remember: It’s bullet path, bullet path, bullet pathnot the barrel that you’re aligning the scope with.

The above is a top view, looking down at the rifle and scope, and bullet path(s). The blue area would represent the scope’s range of WINDAGE alignment; in other words it can be dialed to windage zero anywhere in that blue zone. The orange lines represent the various paths different load recipes might cause the bullets to fly. You can dial the scope to align with any of these paths.

All that really matters is that the bullets be released relatively close to the vertical crosshair and all will be well.

When the barrel releases the bullet, the bullet goes up, then it comes down. It does this regardless of where the barrel is in relation to the scope. All you are doing with the scope windage adjustments is aligning the erector to be closely parallel with that bullet’s path. The key words here are CLOSELY PARALLEL, and once the scope’s windage is set to be parallel with the bullet’s path, you will not have to change windage for various ranges–it’ll stay the same–even if the barrel is at 5:30 or 6:30, or even 5 o’clock or 7 o’clock underneath the scope. You might get lucky and have your bullet fall perfectly along the vertical crosshair of your scope, but that’ll be the exception; not the rule. Chances are, if you could somehow determine the “perfect bullet” path, it would be 1/8″ or even more, to one side or the other of the vertical crosshair. Big deal, though–such a small amount of error won’t be noticed on the targets.

The problem that some of us may have in understanding this is we are assuming that bullets eminate in a straight line from the bore of the barrel–which they do not. Some bores are not even drilled straight through the barrel, so you could have a scope centered “perfectly” over the barrel and still have a “canted bore.” But relax. Hold your scope level for each shot and you’ll still shoot just fine.

I have a ScopLevel on a Bushnell Elite scope. The level is mounted to the tube of the scope, and I move that scope from rifle to rifle as I test different guns and different loads. It’s currently on my recently rebarreled Remington 788, and it is not perfectly straight with the receiver. I noticed this when I put the rifle on a bench at our rifle range. However, since I began testing that rifle, I have hit varmints at 200 yards, 540 yards, and 755 yards by making elevation changes only. I did not make windage changes for these shots because the wind wasn’t at issue. A couple weeks ago, again, without touching the windage turret, I dialed in my elevation for 1050 yards and shot at this target:

While the group has moved a tiny bit to the right, that is to be expected at such long ranges as the bullet’s spin causes it to move slightly aside.

Paralleling the scope’s line of sight with the bullet’s path is really no big deal.

Keep the scope level, and don’t worry so much about whether it’s perfectly straight up and down over the bore. It’s nice, yes, to have a straight scope. But if your scope is slightly canted in the mount, just level the crosshairs as you normally would, and you’ll have no trouble at any range.

One last illustration, which I hope will bring it all together…

Dan Newberry

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