SIG SAUER M400 Tread Predator
Courtesy SIG SAUER
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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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    • It’s not that a 16in barrel is short.

      It’s what does the m400 predator only have a 16in barrel with the PRS type stock and 14 in handguard?

      It’s just a bit of a diffrent set up

      It wouldale sense if it had a collapsible stock and/or iron sights. As it comes, the handguard is too long unless it has a rifle gas set up.

  1. Yes, barrel length is a variable and changing it will change performance, accuracy, etc.

    My questions for Josh…
    Is 16 inches short?
    Is 26 inches long?
    Would you call 6 inches short? What about rifles with 30 inch barrels?

    This sounds like ‘high definition’ to me. What is ‘high’? Is it 720p or 1080p? These are terms that are in flux and change according to the user.

    I take issue with the question “… Why Are The Rifle Barrels So Short?”. It’s a ridiculous question. They are not short. This is what it’s made with. This sounds like 30 round magazines being referred to as ‘high capacity’ when we have 100 round mags.

    • “This sounds like ‘high definition’ to me. What is ‘high’? Is it 720p or 1080p?”

      The highest commercially-available is 8K, at 7680 x 4320 pixels.

      4K is about the highest you will see stocked in places like Best Buy, and that’s 3840 x 2160…

  2. So the point here could be that if you are persnickety about maximum possible speed and accuracy to the nth degree, using a longer barrel gun is just as reasonable as it ever was. If you are not so intense about those last few feet per second or foot pounds or sub-fractional arc-seconds of coyote, a shorter barrel will serve you.

    And the coyote is just as de-varminted either way.

  3. Your chart illustrates the biggest difference. Shorter barrels yield less velocity. Does the velocity difference mean anything? Depends on the situation. In the woods it doesn’t, in a wide open field it might.

    • Over short (ie 300-400m) probably not. Over 600-800+, definitely. After 800m you can get transonic velocities out of 308. You want to keep bullet velocities above the speed of sound as long as possible.

      G&A did a test where they cut the barrels of a Remington 700 and Winchester model 70 from 24″ to 16″ in half inch increments. They expected the velocity to reduce and the groups to open out. The velocity did reduce, but not as much as was expected. The groups open out, then closed, opened again, then closed, and repeated one more time.

      A firearm barrel is like a tubular bell. The tightest groups were where the muzzle was at a node, and the other groups were where there was movement. This is how you can tune a gun by either altering the length of the barrel, using a harmonic dampener such as the Browning BOSS, or adjusting the ammunition to suit the gun.

  4. Something that I feel you neglected to mention is substantial improvements and cost reduction in range finding and perhaps not enough emphasis on bullet improvements although I feel you’re pretty close there.

    At medium and longer ranges it’s not that more velocity would affect accuracy but rather that the kill zone of the bullet would increase and make the range of the bullet less sensitive. As an example lets say that we have a 243 win loaded with 105gr Nosler Custom Competition Bullets and a charge of IMR 7828 powder (.517 G1 BC, 2770 FPS roughly for max load, lets say 2540 for min load from an 18″ barrel.)

    The point where you hit 15″ drop between 25 yard increments is 775-800 yards with 2770FPS MV. At 2540FPS that comes out to 675-700 yards. It’s not a lot but it’s certainly margin and it means if you’re pushing distance it becomes important if you’re not as certain about your distance.

    Lets bang the calculator against something older, like the Winchester 100gr Super X or Remington core-lokt that was a staple deer bullet in 243 for decades. That’s a BC of .356 with a 100gr bullet at 2960fps rated with a 24″ barrel. With my 18″ barrel lets say that’s 2700fps at the muzzle. Based on testing I’ve seen that seems not too unfair. The point we reach that 15″ delta is 625-650 yards. This means that after that range my margin for error goes up fairly significantly if I’m looking to score a critical hit. Now then lets bump that back to 2960FPS. Magically we end up with 700-725 yards, slightly above the low velocity high BC bullet’s range.

    Naturally if you understand your drops well and you’re able to accurately gauge the distance (with better technology that becomes more accurate and significantly easier) then being able to use a rainbow trajectory suddenly becomes a lot more plausible.

    I’m somewhat over simplifying this but I think it’s an important piece of context in terms of why the artifact of long barrel length existed in its day and that we’ve in many ways negated it via better range finders and better bullets.

    Like anything else however, the answer is totally dependent on the context of which the rifle and ammo are being used. A 45 ACP SWC is a brick BC being shot at a velocity that’s just slightly higher than throwing a brick at someone but it’s totally suitable as a round if the creature or object being shot is is close enough.

    • A chronograph and ballistics software take a lot of guesswork out of the equation.

      A Chrony F1 is a worthwhile investment.

  5. Barrel length should be as long as needed to burn at least 95% of the powder before the bullet leaves the barrel. Matching powder burn rate to barrel length was not as well understood years ago. YES – short barrels are “stiffer”, and barrel harmonics are very important, but modern manufacturing technology and powders have overtaken much of the problems of the past. Just think of “new” cartridges like the .300 Blackout.

    • Powder burn rate is something I didn’t think of either. That’s an interesting notion and with semi autos becoming popular these days it also means that some of the super super slow powders that can be used in longer barrels can’t be used without tuning.

      As an example I’ve got some Ramshot Magpro and it’s no go for my LR-243 even with light loads. The gun just doesn’t like the pressure curve. If I had +length gas and a small port size maybe but there’s a good chance I’d be playing around with it getting it to work well with lots of rounds.

      • My .22-250 really likes IMR 4895, which wants a longer barrel. It might even do a bit better if it was 26″ instead of 24″ and it certainly wouldn’t do well if I chopped it down several inches. It already has a fireball that lays the grass down. Now, in a different rifle that liked a different recipe, a longer barrel may not be quite so important in this caliber.

  6. As Andrew pointed out context is key. Josh is a assuming a generic hunting context. That doesn’t make AI old fashioned and kinda dumb for manufacturing 27″+ rifles.

  7. From the referenced article :

    “Additionally, calcium carbonate was added to the powder which drastically reduced the muzzle flash of the new ammo.”

    Can someone who actually knows clarify as to why that is so? Is it a physical or chemical interaction during combustion?

    • I don’t know. If your blowing half the burning powder out the barrel adding sawdust takes up the space of the powder blowing out the barrel.

  8. Length of barrel has nothing to do with accuracy. Short barrels save the manufacturer money ,make nice fire balls, increase muzzle blast and reduce velocity .

    • “Length of barrel has nothing to do with accuracy.”

      It does to a point, but beyond that, it probably matters a whole lot less than some folks seem or want to, believe… 😉

      • A bloop tube will increase sight radius on a short barreled rifle if one is limited to iron sights.

  9. im no sig fan boy
    having said that there was certainly a lot of ignorance and chest thumping last time this came up
    at the end of the day…16 inches…is enough barrel…for most people…most of the time…at the most distances…that most people…will shoot the most varmints at…


  11. I defer to Mr. Wayner’s real world experience. It must be frustrating when random people who do not have as much experience as you do (and the science backs it up) challenge you . . . not so much as a “BUT” (you knew it was coming) rather more like an “AND”, you do lose some velocity/kinetic-energy with a shorter barrel and that has relevance to other factors besides accuracy- namely penetration and defeating obstacles.

    Not as much of an issue with smaller calibers as past a certain point velocity wise projectiles frequently cannot stay intact upon impact with a hard surface. Slower sometimes penetrates better as the projectile maintains stability and does not break up on impact. With larger (and usually slower) calibers though it makes a difference when punching through stuff. For me the issue is mostly academic anyway as being a civilian myself I do not think the odds are I will need to defeat any barriers 🙂 Good write up.

  12. I can’t disagree with anything that Josh wrote. I’ll just add that when using iron sights, a longer barrel is definitely better. Unfortunately for me, even though I really prefer shooting with iron sights, my eyes aren’t cooperating like they used to. I used to be able to hit 300 yard targets with irons. Now, I need a good scope and a guide dog.

    • It helps using a 24ft long barrel at a 25ft target.
      300 yards you’d need more sawhorses and a winch truck.

    • “I used to be able to hit 300 yard targets with irons. Now, I need a good scope…”

      You and me both. Cataract surgery cured one problem, and introduced a few new ones, like making some thing in the intermediate focus range, strange.

      “…and a guide dog.”

      I figured the cat would deal with the dog… 😉

    • Longer barrel equals longer sight radius and more precise aim and adjustment.

      Muskets had long barrels so in volley fire the muzzle of the back rank’s guns were still in front of the forward kneeling rank. And with the bayonet made an effective pike against cavalry.

  13. Well, I don’t know all that much about those small bullets the only small-caliber rifle I shoot is a 22 never liked the 223 guns I stick with 30 cal. 165-grain bullets in my old 3006 and 154 to 122 in my 7.62×39 guns of course here in FL.dodon’t have a long-distance varmint hunting anything I need to shoot at a distance the old 3006 will handle it it is an old but good gun

  14. If it’s a M1A it is going to have a 22″ barrel period. If it’s long range it’s 26″ period. If it for everyday a 16″ AR is suitable. AR accuracy comes from more than just the barrel whether it be 16, 18 or 20 inch. In other words…Don’t bring a 16″ pencil profile barrel to Camp Perry.

    • I’m not bringing anything to Camp Perry as I don’t enjoy the game of golf, especially a very loud game of golf with ridiculous shooting coats and fudd RSOs.

  15. The website for this SIGM400 Tread Predator rifle says it comes “with a Cerakote Elite Jungle finish to minimize visibility in woods or brush environments,” so why the F does it have those bright, neon- yellow “Tread” panels on both sides at the front of the handguard? Are those removable, and if so, what’s underneath them, Picatinny rails? Velcro? Bright neon-yellow doesn’t belong on a gun unless it’s a toy Nerf gun. I assume they’re rail covers, but they’re so ugly and glaringly bright that they’d go straight in the trash the moment I bought that rifle (if I lived in a state where they were legal)!

  16. Kind of partial to 18-20″ barrels myself. Rather give up 100-140fps than 200fps and they’re handy enough. I’d think at longer ranges the time to target would become more critical than accuracy since bullet drop and windage loom larger with every yard. Wind in particular is rarely constant.

  17. I read somewhere of some practical shooting tests which came to the conclusion that the main benefit of a longer barrel was the longer iron sight radius.. If your sights are twice as far apart, it’s easier to line them up on target.

    It may have been connected with some doodad which hung off a pistol barrel to give it long sight radius and increased its accuracy. I forget those details now and may be conflating two different articles.

    • I like a longer barrel for the efficiency of the powder burn. I’ve got a 24inch on the weatherby it needs a 26, the 24 drops my velocities down into the WinMag realm. Don’t like win mag because using big bullets takes up powder space so that puts it into the 30-06 realm.
      Anybody want to trade a 30-06 for a Jap Weatherby ? LOL.
      If I was to put a rebarrel it’d be 28″

  18. Longer barrels yield more velocity, which can appear to be more accurate because they are flatter shooting, and thus more forgiving to misjudgment of holdover for wind or distance. With iron sights, the sighting radius is increased, so they are can be more accurately aligned with the target.
    Optics make the sighting radius irrelevant. New, higher BC bullets can retain their velocity and shoot flat at lower muzzle velocities. If using traditional calibers and bullets, etched ballistic drop reticles, range finders (electronic or reticle), wind meters, etc let you accurately hit targets at various ranges without much effort, even if the bullet arcs like a little league outfielder throwing to home. The only absolute advantage a longer barrel has is the higher velocity will keep the same bullet from transitioning to subsonic for a longer distance,, yielding a greater extreme range of reliable accuracy.

  19. I used to spray and pray only, but now that ammo is so expensive I have to actually aim. I don’t like it as much.

  20. I know from personal experience that in 308 length does matter. I have tested two Rem 700 SPS rifles side by side. One with a 26 inch bull barrel and the other with a 20 inch bull barrel. There was over 200 fps difference between the two. Both have good scopes with target turrets and I have data on both guns. Out to 200 yards both are amazingly accurate. Past that the drop on the 20 inch is starting to show. Can I shoot 1000 yards with the shorter rifle? Yes, I just need a lot more adjustment in the scope. Is shorter just as accurate? Probably so , if you know your equipment. Is the longer one better for distance? For me yes. It has a flatter trajectory over the same distance due to the increased velocity. These tests were done with 168 gr. FGMM. It looks like I will be loading differently for each as a result of this test, which will continue. As for me and my rifles, longer is better.

  21. I’d add that with a manual bolt action, 100% of your gas pressure (ideally) goes to pushing the bullet out. In a gas impingement or piston semi-auto, part of your gas pressure is redirected somewhere down-barrel to drive the action. For this reason, I’d keep the amount of barrel that’s forward of the gas port to a minimum, if the goal is to squeeze out every last FPS you can get.

  22. Here in eastern NC my 20 inch AR15 will do everything I need a 5.56 to do. 75 grain gold dots at 2800 FPS works on everything from coyotes to stuff I have no business hunting with a 5.56

  23. A smart person who isn’t a fudd from the 1980s knows that modern cartridges like 338 lapua and 6.5 prc will work best in 16.25″ barrels plus it’s easier to carry in the forest and put in the truck

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