SemiAuto for long range shooting1

Long Range Shooting with a Semi Auto

In Blog by Rich35 Comments

I see the question asked all the time. Why not use a semi automatic rifle for long range shooting? It would make a great competition gun, right? Yes and No. Maybe you’ve heard the other side of the argument? You know, the one that says semi automatic rifles can never be as accurate as bolt action rifles. Like all myths, there are elements of those surrounding the use of semi automatic rifles for long range shooting that are factually correct. There are also elements of the same notions that are just ridiculous and not true. We’re going to examine both sides and let you, the reader, make the call for yourself.

Semi Automatic Rifles in Long Range Shooting

We like to start articles like this by defining exactly what we’re talking about. For the purposes of this article we’re going to refer to a Semi Automatic Rifle (SAR) as a large DPMS or Armalite pattern rifle often referred to as an AR10. Basically, its a scaled up AR15 firing larger 308 family cartridges. While 308 SARs are popular, we’re seeing a lot of them these days put together with ballistically superior calibers like 260 Remington, 6.5 Creedmoor, and 6mm Creedmoor. This helps get the better ballistics out of the same package.

Myths of SARs for Long Range Shooting

I’ve heard it many times, I’m sure we all have. “A semi automatic rifle will never be as accurate as a bolt action rifle.” Well, in the old days maybe that was true. In modern times of computer controlled CNC machines that produce receiver sets to very precise tolerances and gunsmiths that know how to put the packages together, that just isn’t true. The rifle I built in 6.5 Creedmoor pictured at the top of the article shot half minute or better at 100 yards with factory produced Copper Creek Ammunition while the barrel was still brand new and picking up speed. We reviewed that ammunition and you can read that review here.

Measured >0.5"

Measured >0.5″

The barrel picked up a good 200fps since the review of the Copper Creek Ammo. Having burned up the ammo from the guys at Copper Creek I developed a hand load using 123gr Lapua Scenars which has proven equally accurate and capable in a number of matches. Frankly, the gun shoots better than I do and that leads me to discussion of the whole ‘gas guns can’t be as accurate as bolt guns’ argument. That really isn’t true. SARs can absolutely be as accurate as a well put together bolt action rifle. However, it is not as easy to achieve that high level of accuracy with the SAR.

Long Range Shooting with an SAR, issues?

What makes an SAR harder to shoot to the same level as a bolt gun? Mainly it has to do with the moving parts of the rifle. With a bolt action rifle when you fire the rifle you have a single recoil impulse to deal with. You feel the first and only push against your shoulder as you execute proper follow through. With a SAR when you fire the rifle, you are dealing with a minimum of three different recoil phases.

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You can mitigate some muzzle movement with a quality muzzle brake like the JEC Customs Muzzle Brake

 

You feel the initial push as the bullet races down the barrel just like a bolt action rifle. You will receive an additional push as the buffer compresses the buffer spring either bottoming out in the buffer tube or reaching the point where the spring halts the rearward movement of the buffer and bolt carrier. You then will actually have some forward movement of the rifle as the the buffer spring extends and snaps the buffer and bolt carrier group back forward and into battery. To put it mildly, there’s a lot going on because the gun is doing the work the shooter has to do with a bolt action rifle. It’s extracting and ejecting spent cartridges and loading the next round up.

It is mainly the follow through fundamental that is so critical to achieving the accuracy potential of an SAR. If you are lax on your follow through as it moves through the different phases of the complicated recoil impulse the gun will start exploiting any weaknesses of the shooter.  You see it with the gun moving off target. That makes it difficult to keep the gun’s point of aim the same on subsequent shots. There is another issue that seems to be cropping up with large frame SARs in higher pressure calibers like 260 Remington, 6.5 Creedmoor, 6mm Creedmoor, etc.

The issue is the larger SARs can really start beating up on brass. The extra pressure translates to a harshly cycling gun. There are products that can be used to tame the pressure and alter the timing of the cycle. When I first put my 6.5 Creedmoor together it was ejecting brass with such force that I was getting brass rubbed off on the case deflector. Then the spent cases were landing 6-8 feet to the 2 O’Clock of the ejection port. Additionally, the gun was cycling too quickly. The bolt would start to unlock while the case was still under pressure. As the bolt unlocked the ejector would take half moon shaped chips out of the case head. Since the bolt had unlocked and started to open the case head was no longer supported. This leads to prematurely loosening of the primer pockets.

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Color levels of this photo were altered to try and bring up the half moon ejector marks, you may have to view the photo full size to see it

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No flash or color options showing the case heads in this photo, the half moon gouges from the early unlocking are more obvious here

Since somebody is bound to ask about the load itself, I’ll explain briefly. The only signs of pressure are related to the fast cycling of the rifle. I’m not getting the ejector gouges in the typical round stamp, its more of a half moon gouge from the bolt unlocking while the case is under pressure. Additionally the primers themselves are round as normal without any flattening. The gouges didn’t get any better or worse during load development and I ran it up to and even a little past maximum in small increments. The gouges were present at even the lowest beginning charges. It is a timing issue, not a pressure issue. My final load wound up being most accurate almost a full grain below maximum.

Frankly, the SARs seem to be much more pressure and timing sensitive with the better ballistic calibers. Most of the top gunsmiths recommend you not even run a 140gr projectile in the 260s and 6.5 Creedmoor rifles. The 130gr and under projectiles do almost as well ballistically and with much less in the way of pressure and timing problems. Its pretty well documented and if you aren’t familiar with it just do some Google work and I’m sure you can find it.

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Products used to slow down the cycle of the rifle, a Full Weight Bolt Carrier Group, Tubb Flatwire Spring, Tubb Carrier Weight System, Ultra Heavy Buffer from Heavybuffers.com

Upsides to SARs for Long Range Shooting

What about the upsides? It can’t all be bad, right? There are some definite upsides to using an SAR for long range shooting. For starters, there’s magazine capacity. Finding 10rd, 20rd, or even 25rd magazines now is easy and reliable with Magpul’s offerings. There’s something to be said for not having to reload the gun on a complicated stage at a long range shooting match even if you are having a bad day and wind up running the maximum round count.

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20 Rounds of 6.5 Creedmoor is a lot of firepower packed into a rifle that doesn’t need a reload during even complicated stages

 

The modular nature of the SAR platform is a definite advantage. There are countless options from stocks, to grips, to handguards and other accessories. The sky is the limit and you can customize the unholy hell out of an SAR based on the AR10 platform. It also makes bigger jobs like a barrel change easier. Instead of having to mail the gun off if you have the right tools you can swap a barrel out yourself. Or, if you have the extra money, you can build another upper receiver in a different caliber and swap uppers just like with an AR15. Whatever your heart desires, there’s a part for that.

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Stock options, you bet! This rifle is configured with a Magpul STR stock, Battleline Industries SAPR, and enhanced recoil pad

Some shooters will say you can shoot faster with a SAR than when using a bolt action rifle. I’m not sure that’s true. Certainly you can get rounds fired faster but whether you can fire accurately faster is a bit debatable. In my experience, the speed for accurate fire is roughly the same with a possible slight edge in favor of the SAR. However, we already discussed the issues with follow through and recoil effects as they relate to accurate fire using an SAR. The advantage in speed comes from the fact that you don’t have to break your grip to run a bolt. There’s no time penalty while you get your hand back on the grip and your trigger finger re-indexed on the trigger. However, since you have to break your grip to dial adjustments even this can be argued as not much of an advantage.

Mounting points for accessories are plentiful on SARs. So if you need a spot to mount a sling attachment, or a light for a night stage, optics, barricade pads, whatever you might need to mount on the gun, the SAR has a way to mount it. Some stocks and chassis options for bolt action rifles offer similar amenities but the bolt action rifle definitely lacks the modular nature of the SAR.

Wrapping Up

So we talked about a number of disadvantages, and a short list of potential advantages of a semi automatic rifle when compared to a bolt action rifle for the purpose of long range shooting. At the end of the day we have two different rifle configurations with a lot of similarities and not that many significant differences. What this really boils down to is personal preference. Which option are you comfortable with and which option do you enjoy shooting? If you are a serious competitor looking for every edge you can get the semi automatic rifle may not make sense for the kind of long range shooting you do. On the other hand higher capacity and rate of fire can be advantageous on a battlefield.

You really just have to evaluate the long range shooting task you plan to undertake and then decide which rifle configuration makes sense for what you want to accomplish. If you need every edge in precision, maybe the bolt gun is the way to go. If you plan to be engaging multiple targets under time from awkward positions the semi automatic rifle may make sense. Evaluate the task and assess any weaknesses you have when trying to determine what you hope to gain from either platform. Semi automatic rifles are a lot of fun and when given a realistic set of expectations can perform at a very high level.

Owner and Proprietor of AccuracyTech, LLC. Rich is a Firearms Enthusiast, Precision Rifle Competitor, and Writer. He is committed to bringing readers quality reviews and articles related to the Precision Shooting Sports. If you have any questions for him, please use the contact form on the site.

Comments

  1. very informative info,like to hear about fun shooting stuffs!!

  2. The problems you described with ar type rifles in these larger higher pressure rounds sounds to me that a slow burning powder is resulting in higher gas pressure at the gas port and driving the bolt and carrier faster and harder than it was designed for

    1. Author

      I agree, unfortunately I think the solution is a longer than “rifle length” gas system!

  3. I had no idea that you would answer so fast. I really liked your article, I am a older shooter that needs step up to some higer ballistics and your article was right on point

    1. Author

      I can typically answer questions pretty quick, unless work has me occupied! Thanks for the compliment, glad the article helped!

  4. If you have a +2 gas system, combined with an adjustable or bleed off gas block, do you feel the full weight BCG, Tubbs and heavy buffer would still be necessary?

    1. Author

      I can’t say, but certainly the issue is dwell time. By extending the tube, and limiting how much gas travels through it, you’ll extend the dwell time and that’s really what AR10s seem to need to run well. My next barrel will likely go in a similar direction with an extended gas system. I think you’ll still want the full weight carrier, and probably the heavy buffer anyway. You might get away with not needing the Tubb carrier weight.

      My AR10 in 6.5 Creedmoor is still unlocking a bit early, not enough dwell time. However, I did manage to get it to stop hucking the brass 20ft from the rifle but only after utilizing the full weight carrier, the heavyweight buffer, flatwire spring, and the carrier weight system with the tungsten weight. Even with all that, the dwell time is still a little low and I’m thinking that’s a problem only solved by the extended length gas systems. How much weight you need with regard to the other components mostly depends on how hard/fast the gun is cycling. An adjustable gas block isn’t always enough to slow it down to an acceptable level.

  5. I know that I am behind the curve, also my comments are simple, and won’t be any help. But as the M1 and the M14 plus the M16 and AR10, are basicly designed to operate within a specific chamber pressure, bullet weight and powder within a certain range of burning rates to make the gas gun perform. Change these perimaters some what, a true ballistic proformance change,the newer much higher chamber pressures and longer heaver higher BC bullets and band aids will only go so far. Gas guns may be reaching their limit. John Browings M2 50 cal is recoil operated, Maybe springs might be easer to devolope than trying to balance the type of powder we need with the gas byproduct that it produces .

    1. Author

      I am sure you’re correct as far as parameter changes mucking up the systems by going outside their original intent. I do believe that modern gas guns can be made to run properly, but it will take some tweaking of those parameters.

      Namely, longer gas systems to extend dwell time on higher pressure chambers and heavier components to slow down the cyclic rates.

      I don’t think you’re behind the curve at all, brother!

  6. I want to thank you for replying to my comment, It made me read and think a lot and I have a new understanding of your depth of development. It looks to me like you are developing a real separate process and control of the same gas that provides the energy for the new high pressure rounds and still provides cycling and long range precision. I am going to watch and learn, I really never got past bent op rods. I want to thank you for your work and your ability to write about it.

    1. Author

      You’re welcome, Sarge! I appreciate meaningful comments that provoke thoughtful discussion.

      My experience is with AR10s and not the M1A, though I’d love to have one and it’s on my list for acquisition! I think the real benefit of AR platforms is modularity. Different parts from different manufacturers typically work together, within reason.

      The problem, as you mentioned, is that we’re living in a time where we’re taking the platform outside it’s original design parameters. That’s not a bad thing, but it happens to kill some of that modularity and a more custom approach becomes necessary to get each rifle working the way it should.

      The key there being “the way it should.” People throw AR10s together all the time, and they’ll work…

      Do they work well, though? I sheared an extractor hook off a bolt in a big match. The gun was horribly overgassed, and I didn’t know any better. I see guys posting photos all the time of AR10s they threw together. They’re all chewing up brass because the dwell time is too short and the cyclic rates are too high.

      There’s doing it, and then there’s doing it right. I’m trying to make my rifle work properly, instead of just letting it eat brass and components like a monster.

  7. I have a 24 ” fnh bolt awesome rifle, I am getting a rock river 26″ sar.308 varmint rifle. I have been doing research which led me to your article. Thank you for helping me over the fence. You dealt with the topic in a reasonable way. I am also seeing the benefit of 26 over 24 inch barrel from a ballistics perspective. the plan is range time to see the difference .the key you gave me is application. Thank you again.

  8. Hi Rich any way you would list a name or two of 26 inch semi auto 308’s. I am looking at a Rock River lar-8.308. Not for price as much as I took a liking to it. However accuracy and precision being the point I am asking your thoughts. thanks.

    1. Author

      Hey Thomas, if you’re going factory builds and want real accuracy I’d look at a GAP 10, not cheap or quick to come by.

      You may have more luck getting your hands on a Seekins SP10 than the GAP rifle. I don’t think either will let you down in accuracy.

      Keep in mind with a big AR that accuracy is as much, or more, about the shooter than it is about the gun.

  9. Hi Rich it appears barrel length does not need consideration? As much as quality of build and shooter ability. the rock river is [email protected] at 26 inches. Both the GAP and Seekins are sub moa with 18 and 22 inch barrels. That’s impressive for ARs. Are those considered long range guns ? or better served custom building ? if you are open I would like your thoughts on that. thinking about 3500 to4500 in dollars. Thanks for your responses.

    1. Author

      Hi Thomas, barrel length doesn’t really have an effect on accuracy. What barrel length really influences is muzzle velocity and effective range.

      You mentioned 308 Winchester. You can get away with a pretty wide range of barrel lengths in 308 and still have an accurate rifle.

      The GAP and Seekins would be considered long range rifles, for sure. As far as whether you’re better off building or ordering it kind of depends on budget and knowledge.

      I think in your case you’re better off ordering one. I’d take a hard look at the Seekins and try to start thinking about glass while it’s being produced.

  10. I had a JP LRP-07 in 308 (20″ barrel) and then got one in 6.5 creedmooor (22″). They are both awesome and both easily shoot sub moa.

    1. Author

      Sorry about that, Bruno, you got caught in spam filter. Two JP rifles, you must be a surgeon!

  11. Hi Rich – just discovered your blog, thanks for the work. I have some comments re AR10 in competition. I built an AR10 in 260 earlier this year. I had the advantage of some good advice, and started with a rifle +2″ length gas system, a JP adjustable gas block, and more importantly, a JP Low mass carrier and “silent captured spring” buffer. The combo reduces the oscillating weight over a regular BCG by 12 oz! This makes it a lot easier to see through your shot, and follow through. I too started off too highly gassed, and had a serious failure to eject problem because the cycle time was way too short. With just enough gas now to lock back the bolt on an empty magazine, it shoots very smoothly. Brass lands in a neat pile just 18″ away at 4pm. While not sufficiently accurate for a benchrest gun, it is a 0.6 to 0.7 MOA rifle (Berger 130 AR hybrids over 42.5 gr H4350, 2760 fps), and plenty sufficient for typical tactical steel events out to 900 meters+. A further advantage SAR have is that they are typically 4-5 lbs lighter, and 4-6″ shorter than a typical 16# competition bolt gun. In positional stages (eg kneeling, sitting, barricades, piles of rock) it is much easier to find a steady hold; and not having to cycle the bolt while in offhand or some other weird position is a huge advantage.

    1. Author

      Welcome, Paul! I can’t disagree with anything you’ve said. I’ve run a SAR in competition a few times myself, and for the hokey positional shots you see in a lot of matches these days, it’s definitely easier to build a position and get some work done without having to cycle the bolt. Obviously weight will depend on how the rifle is built up, but you certainly have the ability to lighten up the rifle and shorten the length of the system quite a bit to make it handier. I’m hoping to put a bunch of ammo through my SAR here in the coming weeks. The weather has been great I’ve just been dealing with some health issues the past several months that have limited my range time.

  12. Hi Rich,
    What is your opinion on the BATTLELINE INDUSTRIES SAPR?
    Thanks a lot

    1. Author

      I like it, if you plan to run a carbine stock, SOPMOD or Magpul, on a precision rifle with optics the SAPR let’s you achieve proper cheek height. It’s very adjustable.

  13. Hi, Rich,
    My two cents on this issue: I am a fan of auto loaders and bought parts to put together a DPMS AR-10 patterned rifle with a heavy barrel, without previous experience on this type of task.
    In the beginning, I installed an adjustable gas block and it solved most ejecting and extracting issues until it failed. Replaced it with a more recognized brand-name adjustable gas block and also added rubber O-rings purchased at the local hardware store to beef up the extractor. Since those two enhancements, no more issues. I can collect the spent cases piled up near-by my bench, and brass is reusable, should I want to reload.
    If or when parts are available, I want to put together another upper assembly in 6.5 Creedmoor. I read the recoil is less than that of a .308 caliber, and that is very appealing to me, plus the 6.5 would have a longer range than the .308.
    Thank you for your article.

  14. What are your thoughts on piston operated system vs gas impingement, with the 6.5 creedmoor in mind?

    1. Author

      I don’t own a piston gun but from what I’ve seen of other people’s experience the gas tends to be more accurate. Less moving parts.

  15. What if one could delay the pressure impulse on the bolt carrier until the bullet left the barrel? Would the incidental movement of internal parts have any significant impact on accuracy?

    For example if you disconnected the gas tube would the accuracy be equal? From an engineering POV a simple delay mechanism (no moving parts) could be created.

    1. Author

      They had a gun set up that way at the 2015 Hide Cup. No gas system, side charging handle, so it wouldn’t cycle till you ran it by hand. I would imagine that would help with accuracy to a point, the lock time is still a lot longer than a bolt gun, though.

  16. I appreciated the article. Right on target. I am a fan and a weekly user of SAR. In my personal experience what I did was run JP Silent buffer with the heavier spring while using a rifle length gas system and an adjustable gas block. Also I added the JP enhanced bolt and voila! a real accurate fine tuned SAR rifle.

  17. why not get a bolt action and a semi auto I mean if you want to be prepared they have specifically two real purposes and those being self defense in a combat mode versus long range shooting of either the hunting or sniping type so the discussion is kind of off target from what I see for those reasons basically

  18. Im assembling a 6.5 cm sar. Im using a recipe from many manufacturers but I’ve yet to decide on bolt and barrel. Any suggestions? Im leaning towards jp industries.

    1. Author

      JP has made some real strides to get the pressure under control and properly managed so that’s probably a great choice!

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