Best Barrel Length?

[Whelenon]

I'm told the optimum barrel length for the Grendel cartridge is 19.5". True or false? I have on order a 16" barrel(mid-length) and an 18" barrel(carbine-length). Which one to use? The rifle will be used for deer hunting, 150 yards and coyotes, 300-400 yards. Trying to keep the weight to a minimum but accuracy trumps weight. The 16" will probably arrive first, do I use the 16" or wait for the 18?

Whelen

[Drifter]

My guess is that the 16" would serve your needs fine inside 400 yards.

[bwaites]

Bill Alexander's personal favorite is 18", and if I recall correctly his coyote rifle is that length.

16" will easily get you 400 yards if the difference in weight and length is a concern.

My GDMR is 19.5 inches long, and I find it very nice length wise.

[LRRPF52]

I think one of the most over-looked factors in choosing barrel length for rifles and carbines is your own physical height/build. There are plenty of guys I know who look like they're holding a pistol when a 16" or shorter carbine is in their hands, and you have a hard time finding a long enough stock for them. Then there are guys/gals who can barely hold up an 18" or 20" rifle without looking ridiculous. I personally wanted as compact a Grendel as possible, with decent velocities as well. I'm 6ft, so I wanted an 18" but settled for a 16" based on availability at the time, and have been happy with it now that I'm more familiar with the cartridge's capabilities and limitations. For me, the 16" mid-length shooting out to 600 with lighter bullets is what I have nestled into, and I have a very portable stick-even with a rifle-length handguard and rifle optic.

My thinking is if I'm going to have a heavy, longer AR, it will be an AR10 in .260 Rem, which is what I have for shooting out to 1100+. The Grendel lets me push a ballistically-similar projectile to .308 out of a much smaller/lighter package, with significantly less recoil, and I like that.

[JASmith]

You get a good feel for the velocity payoff by perusing the tables offered by Alexander Arms. You can also calculate the relationship between barrel length and muzzle velocity for your load by using http://shootersnotes.com/calculator/velocity-estimator/.

The next step would be to look at the trajectory difference for these velocities. (JBM ballistics has a very good trajectory calculator- http://www.jbmballistics.com). The difference may not be much and unlikely to be important if you are serious about 150 yards being the max for deer hunting. The same is true for terminal effects. The 400-500 yard shots at coyote may be more interesting. The bullet is starting to nose over pretty good at those distances, and might make a difference, especially if you're using a conventional hunting scope where you are most likely to be applying Kentucky Windage and Tennessee Elevation to get hits at the longer ranges.

If you are planning to use a more or less conventional duplex or mil-dot scope, you can get an idea of the sight picture difference by running the sight-picture calculator at http://shootersnotes.com/calculator/quickpix/. You'll need to enter your own range, drop, and drift information and repeat for the second trajectory, but you'll get a feeling for how much your sight picture would change in going from the shorter to the longer barrel.

[Whelenon]

Thank you gentlemen, very helpful. I haven't put a Grendel round down range yet but this forum has been a wealth of information. Once again thanks.
Whelen