Performance AR-15: Long-Range 6.5 Grendel

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An Alexander Arms AR in 6.5 Grendel bangs steel fast and furious past 600 yards with ease.

What the 6.5 Grendel has to offer:

• The 6.5 Grendel was designed as a medium-bore hunting cartridge for the AR platform.
• With high BC bullets in weights from 120- to 139 grains, the cartridge is a long-range winner.
• Heavy barrels and long-range scopes tap the cartridge’s full capabilities.

It was a warm summer day. We were a bunch of gun writers on a PR trip, and we had exclusive use of a 600-yard rifle range. At the back end, behind the target frames, was a steel half-silhouette. We lasered it at 640 yards.

We got a rifle zeroed to the point that it was hitting that steel, and someone came up with the idea of a contest. But what kind? Well, most hits. Hmm, we have a squad of competitive types and a mountain of ammo. Who wants to see a barrel burned up as we try to make it 20-30-40 hits in a row?

Best hits out of five shots. Yes, and when we’ve all shot five hits, then what? OK, here’s the plan: five shots, scored the most hits. Shortest time is the tie-breaker, but to add pressure, any shot over ten seconds doesn’t count.

Use anything on the range, table, chairs, bench, sandbags, to build a shooting position that isn’t prone. Time starts on the beep.

For the longest time, four hits in just under ten seconds was the winning score. Then I found a shooting position that worked for me. It was awkward to look at, it had nothing in common with the classic shooting positions, but it afforded me one great advantage: I could see my hits (and misses) through the scope. On my last run I hit the steel five times in five shots, in just over seven seconds. Winnah!

The rifle was an Alexander Arms 6.5 Grendel with a 20-inch barrel and a Leupold 3.5-10x on top. Having won the contest for the day, I had to have a rifle, so I asked Bill Alexander to send me one exactly like it.

Bill designed the 6.5 Grendel to be the best medium-bore hunting cartridge to be had in the AR. The bonus was the case length allows for long, high-BC (ballistic coefficient, a measure of how easily it slices through the air) bullets in 6.5, and that means it is a really good long-range cartridge as well. How much of a difference?

The competitor here is the 6.8 Remington SPC. A typical bullet for it weighs 120 grains and has a BC of .400. The 6.5 Grendel, with a similar bullet weight of 123 grains, has a BC of .510 (higher is better) and you can buy or load 6.5 with bullets of 139 grains and a BC of .578.

A higher BC means, with all other things being equal, less drop and less wind drift. Drop wasn’t the problem on that afternoon, but wind drift was. Once I knew the drift, I could hold off (Into the wind) and get my hits.

One conversion option of an AR to 6.5 Grendel is to buy a complete upper from Alexander Arms. The advantage is that you have a ready-to-go upper that you can simply install on a ready-to-go lower.

If, however, you want to build one yourself, you need a barrel in 6.5 Grendel, obviously. Brownells lists and makes them. You also need a different bolt. The 6.5 Grendel used as its parent case the 7.62×39. The case was blown out, necked down, and the result was the 6.5. So, you need a 7.62×39 bolt to go with your barrel. (Again, Brownells.)

With bolt and barrel on hand, the rest is all straightforward AR building. The barrel and bolt are designed to fit into standard receivers and carriers, respectively.

I did just this, once I had the AA rifle on hand. My barrel came from a maker no longer in business, and fluted to boot.

I used a VLtor CASV handguard (which they have discontinued, unfortunately) for my build. This gave me a big-enough handguard to hold, without weight, and plenty of room for cooling. I then painted it tan and brown, in a pattern I call “ropeflage.” Paint the base color, then drape rope across the surface and over-spray the second color. The base color shows as stripes, in curves, in the overcoat.

Then it is simply a matter of what scope base and scope fit the job I have in mind for this, or the Alexander Arms 6.5.

Oh, and that afternoon? We heated that barrel up to the point of not being able to touch it, just shooting five-shot groups. And the Alexander Arms 6.5 Grendel still held zero. Nice rifle, indeed.
Editor’s Note: This excerpt is from Gunsmithing the AR-15: Building the Performance AR, available now at GunDigestStore.com.