SIG SAUER M400 Tread Predator
Courtesy SIG SAUER

Recently SIG SAUER introduced the M400 Predator, which I believe is actually a very well thought-out rifle that addresses many of the faults of other so-called predator hunting rifles. But some questioned the idea of a predator gun with a 16-inch barrel and asked if using a rifle with a shorter barrel makes sense.

Barrel length and its effect on accuracy and velocity is something a pay a lot of attention to. I try to stay ahead on real-world uses and there is nothing that says a 20-24” barrel is “better” than a 16” in terms of accuracy. I feel like I write this all the time, and this is another instance: it’s not what cartridge and what barrel length you use it’s what bullet at what speed.

The fact is, a 16-inch barrel is very practical for most modern cartridges. I have several 6.5 Creedmoors I regularly shoot at 1,000 meters at the MTC complex in northern Michigan (a place you’ll be reading more about in the coming weeks) and there isn’t a substantial or practical difference in on-target performance. Practical, in this sense, means that it’s utility-based; I can do 95% of my shooting with it. And in the 5% of cases where I’m shooting for score, I pick a dedicated gun for the task.

The old 24” or 26” varmint barrel rifle is a relic of the antiquated world of the 1980’s when the main barrel length was 24” for almost all calibers across the board, with anything shorter being “edgy” or specialty use only. The draw comes from the American sniper culture, which is slowly becoming something of an antique itself. The civilian marksman these days is arguably better equipped and better trained than many in the military.

Many civilians run schools that teach the military, not the other way around. Granted, some of the best instructors have a military background, but many don’t. Today’s PRS scene delivers features that the military now borrows and uses. Virtually all sniper rifles in use today are the result of civilian companies, not state-owned ventures.

Courtesy SIG SAUER

Back in the old days, the 24″ to 26” barrel was considered to be the standard for long range shooting. Scopes weren’t even close to as good as they are today as far as repeatability and the relationship between bullet and speed was largely reliant on what was available in supply chains.

Snipers used to lead the way for long range in this sense, as they had, at the time, the best gear from the best makers, but were for the most part shooting target bullets in the 168-190gr .30 caliber family.

To get these large bullets going faster than .308 Win/7.62 NATO, you needed to go up to 300 Win Mag. Even then it was a compromise because that round was never designed to use bullets seated far out in the case, thus limiting the shape, weight, and profile of the projectile itself.

In short, the old days saw a compromise that was halfway between snipers using regular ball ammo and something custom made; it was a half measure that yielded adequate results. Even the best ammo at the time, such as M118LR, is now sub-par even to “long range” hunting ammo commonly available on the shelf. I don’t make the rules, I just go shoot and tell you about it.

There is a great amount of development happening in optics and ammunition technology, but not so much in guns. For reference, we’ve been fighting in Afghanistan longer than the timespan from the M1 Garand’s adoption to the adoption of the M16. We are at something of a technological plateau in gun design, and that’s a good thing because it allows for better overall gun products that can perform to the same degree of precision modern optics and ammo are made with.

We can now have fully matured platforms like the M400 Predator that are not handicapped by longer barrels. You simply don’t need a 24” 5.56 to hunt varmints considering that the AR platform is 1) not inherently as accurate as a bolt action (fight me, but it’s true) and 2) there isn’t enough of a difference in velocity at normal hunting distances to matter in the first place.

Add to that the fact that many people are using suppressors and you are strongly benefitted by a more compact rifle. The ammo today supports this, where in years past it did not.

A 17” 6.5 CM is fine to 1K with no complaints. Here is one in a Q Side Chick chassis.

I’m not saying that people who shoot longer barrels are at a disadvantage in this sense.  But the majority of us in heavily forested states like my own Michigan aren’t interested in long barrels that are difficult to maneuver in dense foliage.

If you’ve ever been in Michigan forest — or any thickly wooded area — the confines are so dense that I use a 1911 nowadays in addition to a 14.5” 450 Bushmaster. I’m even debating swapping my barreled action into a Q Side Chick chassis to make it even more compact for getting in and out of the woods.

The next problem I have with the longer barrels on varmint rifles red herring is that a 16-inch 5.56 is quite obviously superior in ballistics to a .17 HMR or a .22LR, both of which are common coyote rifles.

There again is the idea that a centerfire barrel must be long to be accurate, but the same ballistics experts who say that forget that a 16-inch .22LR is perfectly fine for most people. A fair number of dedicated coyote guys I know even use shotguns regularly. I don’t, but hey, some of them do better than me.

A full-size rifle today rarely has a barrel longer than 24”. The extra length just isn’t necessary as modern powders and case designs make them more efficient. Optics, like the USO 5-25X, make more of a practical difference than barrel length.

The ideas around barrels and ballistics is ever-changing. I wrote about this nearly a decade ago when I started cutting down .308 Win barrels and noticed that there wasn’t much of a difference in performance. While the idea that a shorter barrel equals a stiffer barrel is correct, it isn’t the only factor in performance.

You aren’t going to notice a 40gr varmint bullet at 400 yards being any less accurate from a 16-inch barrel than it is from a 24-inch barrel, and even then, based on my testing with SIG factory 40gr varmint ammo and a 20” National Match rifle (3585 fps) and a base model 16” SIG M400 Tread rifle (3388 fps) revealed that there was a mere 5.5% difference in muzzle velocity.

On paper at 300M there was no real discernible difference and for where I hunt, that would be the max range for a 5.56 anyways. If I was trying for longer, I’d not be shooting a 40 grain bullet.

A typical view in Michigan. The far treeline is about 300 yards away. Note the field is cut about 2-3’ high, much taller than a coyote.

But…for the sake of argument, let’s look at some more loads and ammo types in a 16″ and a 20” barrel.

16-inch(fps) 24-inch (fps) % difference
BHA 52gr Match HP 2957 3067 3.72%
BHA 50gr VMAX 2998 3177 5.97%
BHA 69gr SMK 2699 2806 3.96%
BHA MK262 77gr OTM 2721 2800 2.90%
SIG 60gr HT 2611 2703 3.52%
Hornady 73gr ELD Match 2600 2717 4.50%
Hornady M193 55gr 2973 3089 3.90%


This is just a sampling of 5.56mm ammo I had on hand, and as you can see, there is no real reason to go with a longer barrel when you can eat up that length with a suppressor instead or just go shorter in general to make transport easier.

There is no practical difference between longer or shorter AR barrels for hunting inside 500 yards, the most common ranges used by most hunters. Three hundred yards on coyote is about as far as I would shoot 5.56.

Most people are under the impression that a short barrel is a huge negative, but I’d happily pay 4% velocity penalty and just pick a more aerodynamic bullet like the Black Hills 77gr MK262 instead of a 40gr varmint bullet.

Picking a better bullet can solve most problems and the 77gr load here will retain energy and buck the wind much better than a 40gr bullet out to 300-400 yards, which is the furthest that most people I know will even try to shoot a coyote. They are hard to even detect past that range unless you’re out in open country, in which case I wouldn’t want a 5.56 anyway.

The Brownells build with a SIG SAUER Tango 4 scope. The National Match rifle is 20”, but 16” barrels are now allowed at Camp Perry.

Older generations tend to have an idea of what rifles should be and any deviation is either dismissed or not tolerated. But don’t write off a new product on appearance and specs alone, rather than actually running numbers.

At the end of the day, the difference isn’t that great and with handloads I could get even 77gr loads up past 2900 in a 16-inch gun. I think SIG is validated in choosing a 16” barrel for the M400 Predator as that is what the overwhelming majority of AR rifles are these days.



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