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Old March 13, 2011, 11:42 PM   #1
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.308 Barrel Length

So I have a question about the .308 barrel length.

What is the min. recommended length?

I have been looking at some guns with 16" lengths and am unsure if they will maintain strength and flat trajectories. I know that the .308 uses a faster burning powder than say a .30-06, so at what point does the powder burn up and any extra length become unnecessary?

The main use of this gun will be white tail hunting out to at most 400 yards, but most shots probably around 250 yards. So i am not trying to shoot targets at 1000 yards or anything.
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Old March 13, 2011, 11:51 PM   #2
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a 16" barrel will get you out to 1000 with the right loads. you will lose some velocity off say, a 24" barrel, but you can find loads that will stay supersonic at 1k.

the 308 and 30-06 use practically the same powders. you really only use the slower burning powders when you get up to the 200+gr bullets.
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Old March 14, 2011, 12:05 AM   #3
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Last year my granddaughter did a science project to show the most efective barrel lenght for a 308 rifle, taking inot account ease of carry yet maintaining the necessary barrel lenth to develope about 1800 ft lbs of energy at 300 yards for use in Elk hunting.

What she did was cut a rifle barrel from 26 to 16 inches, to see the difference every 2 inches. Here is the results, it will give you an ideal what you are looking for. She used Remington factory 180s.

The first colume is Barrel length, velocity & energy at the muzzle, then velocity and energy at 300 yards.

26 2826 fps 3,192 2240 2,005
24 2722 fps 2,961 2149 1,846
22 2713 fps 2,942 2141 1,832
20 2677 fps 2,864 2109 1,778
18 2654 fps 2,815 2089 1,744
16 2552 fps 2,603 2000 1,599
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Old March 14, 2011, 12:57 AM   #4
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Thanks that chart is going to help alot.

I did a quick search and it seems that 1000 ft lbs is recommended for taking white tail deer so even at 300 yards the 16" barrel ought to do the trick.
Thanks for the responses
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Old March 14, 2011, 01:29 AM   #5
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I find the chart interesting but it doesn't take into account one thing. You can change powders to adjust burn rate for the barrel length. Also, rate of twist will effect velocity. From my experience a 22" barrel is quite enough to get good velocity out of a .308. With handloads I've gotten 3000fps with a 150 grain bullet out of a 20" barrel. 22" barrels shot the load more consistently but I was able to do it with a 20". For what the author of the post asks I guess the answer is what do you feel is acceptable. I've found that going below 20" tends to drop velocity quickly and it's hard to get back by going to faster powders when you go below 20". Will 16" do what you want? Sure. Will 20 or even 22 inches do it better? Yes! Your trajectory would be flatter and you would generate more energy. The question really is do you want to deliver maximum energy or are you willing to compromise?
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Old March 14, 2011, 01:33 AM   #6
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what a project

Hey kraig, your grand daughter had an interesting project!!!!!!!!! She cut the barrels,.................... what a gal!!!!!!!!

One thing to consider, a 16" .308 may be noisy, like,....... really noisy. You won't notice it on game, but it may be very noticeable at the range and practice, even with muff's.

Plus, 16" rifles may make for a twitchy pointer. Most all the factory sporters, like the Rem 7 and the Savage 10, maybe the Ruger also, in carbine mode, go w/ 18-20" bbls. but that is a personal thing to an extent and you may like it fine.

I've always wished my Savage 10 had an 18" tube instead of a 20".
I think a .308 carbine is close to the perfect GP rifle.
Sort of curious, what rifles are you looking at w/ 16" tubes???
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Old March 14, 2011, 02:02 AM   #7
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bamaranger, I was looking at that new Ruger Gunsight Scout Rifle, 16.5" barrel.

I am still debating on if i can just use a higher burn rate and lower weight bullets or if the muzzle blast and velocity/energy loss will nix this as a gun for me, or if I will even like the forward mounted scope, I understand there are FOV problems with those, I need to handle one to check it out.

If not the Ruger I will either go with the Savage Scout 20.5" length, 1:10", or the Savage Model: 10 FP-SR 22" length, 1:10"

I like to stalk hunt so I figured a shorter barrel rifle would be good, but I don't want to limit myself if I get a longer shot. Also my father in law likes to stand hunt so I will be hunting with him also.

I would like the detachable magazine and the factory iron sights that come on the scout. But the FP-SR does have a lower MSRP and a threaded barrel if I feel that I have to be tacti-cool, they both have different scoping options, so we will see what happens.
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Old March 14, 2011, 07:23 AM   #8
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The most accurate predictor that I have found, is to expect velocity to change somewhere between 1/2%- up to 1% for each inch barrel length changes.
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Old March 14, 2011, 11:12 AM   #9
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You'd use the same medium burn powders regardless of the length. As said earlier, the blast will be something. 18" would be my limit.
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Old March 14, 2011, 01:35 PM   #10
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Rifles that are a wee tad muzzle-heavy for balance seem to be easier to hold on target when out in the field. That's particularly true when walking-hunting and an offhand shot is The Deal.

Sure, a shorty is fine if you're shooting from the cab of a pickup, but I don't see the point, otherwise.

On the steel target at my 500-yard range, a short-barrelled .308 just sorta scratches the paint. My 26" '06 makes dents.
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Old March 20, 2011, 12:19 PM   #11
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I've only had three shots at game that were over 200 yards and that's out here in the West where shots are long. One was at an elk with a .300 Win. mag which is not germaine to the thread but the other two were with shorter barreled rifles in .308 Win. which should be relevent.

Shot number one was with a remington 660, 20" barrel. Load was the 150 gr. Sierra spitzer flat base bullet. (They didn't call then Pro-Hunters back in 1973 as I recall.) The load was stiff charge of H-335 but I no longer have the data. Almost 20 years of reloading notes disappeared when I moved from Nevada to Arizona. No laser rangefinder either.

I and my three hunting buddies paced the distance off then averaged the step count. It was 427 paces. Game was a 195 pound Nevada Mule Deer. The second long range shot was with a Ruger M77 RSI, the Mannlicher stocked rifle with an 18.5" barrel. This rifle is a one trick pony as there is only one load it shoots even reasonably well. The bullet is the 165 gr. Speer Hot-Core over a stiff load of W-760, Winchester bras ans WLR primer. The shot was at 250 yards laser measured.

The bullet hit the chest as the deer was facing me and penetared all the way to a back leg, breaking the bome. I found that a bit of a surprise as the bullet was leaving the muzzle at all of 2550 FPS. FWIW, that same load will do 2610 FPS from the 22" barrel of a Winchester M70.

I tried the load in a new custom Oberndorf mauser I recently had made up and it locked up the bolt. That load is perfectly safe in my M70, my Remington 660, and three Ruger m77 RSI's but locks up the bolt in that Mauser.

I guess I'll have to find a different bullet for those RSI's as Speer dropped the Hot-Core line for a cheaper way to make bullets.

Guess I'll be trying the Sierra 165 gr. Game King hollow points. It took me a year and a half to find a load those Rugers liked and now Speer drops the line. Well, I think I'll try and find what I can and hope it's enough.
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Old March 20, 2011, 10:32 PM   #12
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I've had excellent results with several of the 30-caliber Sierra bullets. Tight groups, good expansion. Inside of 300 yards my preference is the 150-grain flat-base. I load the 150-grain SPBTs when I'm seriously expecting to play Ma Bell.

(Our mule deer season is only 16 days, and the population is sparse. If you aren't confident about hitting at 400 to 500, don't be surprised at being skunked for the season. That might be the one and only shot you'll get.)
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Old March 21, 2011, 12:03 AM   #13
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Below 18" with .308 is going to give you a lot of muzzle blast and noise, although that is dependent on load and subjective to some degree so YMMV. I wouldn't see the purpose of a civilian use for .308 with less than 18" but to each his own. The sweet spot for .308 for accuracy/fps in most loads would be 18-22". Differences within that range (18 vs 20 vs 22") is pretty much splitting hairs.
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Old March 21, 2011, 05:00 PM   #14
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Considering a 308 out of pretty much any barrel is going to be faster than the 30-30 I say you will be all right.

That being said I like my 308's with a 20" barrel for the "right balance" when shooting offhand. I had a 16.25" 308 Saiga once, but it just seemed too butt heavy. Now I have a 20" 308 Saiga that I really enjoy. Also have a 20" Savage 10 Heavy Barrel, and that is a real hoot to shoot.

Machine guns are awesome until you have to carry one.
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Old March 22, 2011, 10:10 AM   #15
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As a point of interest, the G3/HK91 used an 18" barrel. Combat is much the same as hunting, 400m is a long shot for the average soldier.

Note, the difference between 18" and 20" is almost within some loads standard deviation. It's not wrong to consider propellant as one variable you can use to compensate for velocity loss. Lots of handloaders are doing just that to boost speed within limits.

Another perspective is that, even with a 16" barrel, there is still 500 foot pounds more energy than needed at 300 yards. That's about 1/3 more, and considering that the rifle must be built to handle the extra power, the disadvantages are more weight and recoil. Both are about 1/3 more, too, .308 guns average 3 pounds more carry weight, and have 10 more pounds of recoil than an intermediate caliber that still provides 1000 pounds of force past 300m.

It's been said, take enough gun, it seems that the intermediate calibers can do that for 85% of the shooting done. What's interesting is that big caliber fans like to use a 15% situation to justify carrying their favorite 100% of the time.

It's like using a 3/4 ton diesel truck to commute to work. After a while, most stop looking thru testosterone colored glasses and downsize their expectations. And yes, I did sell my .308.

It took carrying the M16 22 years before it sank in, tho.
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Old March 22, 2011, 06:52 PM   #16
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I hunt with a .308 with a 16.5" barrel and it has performed well for me.
The longest shot on game with it was at 162 yards, and it killed cleanly.
Very accurate with Remington Coreloct 150 grain cartridges.
I do have one expanded projectile I recovered from a frontal shot on a white tail doe at about 85 yards.
That shot was also a one shot kill.
The blast dosent bother me anymore than any other rifle.
My Rifle is a Ruger Frontier, but I mounted a Leupold VX 2 3x9x40 over the reciever and had a one inch spacer and a packmyer added to the stock to increase LOP to 13.5 which is my preference.
Hope this helps.
I have not shot game at 400 yards with it however.
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Old March 23, 2011, 03:13 PM   #17
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16" is the minimum rifle barrel length, by Federal law. Some states have (or had) 18" minimum requirements for hunting.

Many good replies so far, and a couple I have to wonder about.

The .308 was developed to use a 22" barrel. And it was developed to duplicate the GI .30-06 M2 ball ammo. In civilian loadings, it, like the .30-06 have been increased over the GI specs, by a fair margin.

A .308 in a pistol length barrel (14" like the T/C Encore) still has plenty of energy to cleanly take deer at 300 yards. ALL .308 rifles have enough. Worrying about the energy from different rifle barrels is immaterial to the question asked. The 1000 lb energy rule is simply a reference point, and not a real world absolute. Note that some states only require 500lbs of energy for deer, from a handgun! If you can take deer with that, you can certainly do it just fine with more. Game laws are rule for sport, and not minimum limits for what can actually do the job.

As a point of interest, the G3/HK91 used an 18" barrel. Combat is much the same as hunting, 400m is a long shot for the average soldier.
As a point of interest, the M14 uses a 22" barrel. The original FAL also uses a long barrel. The original M16 uses a 20" barrel. Machts nichts. The only place where combat is "much the same as hunting" is that long shots are seldom made by the average soldier. Everything else is vastly different.

When you are talking hunting rifles, .308s are not "average 3 pounds more carry weight...etc". This can be true when you are talking about battle rifles/assault rifles in a military context, but for sporting rifles, its simply not true.

I spent my teenage years hunting deer with w Remington 600 carbine in .308 Win. 18.5" barrel. Blast is harsh, and recoil from the 6.5lb carbine is not inconsiderable. However, it performed very well, and was not a tremendous burden to carry. The same rifle in .243 Win or 6mm Rem is easier on the shoulder, and will do as good a job on deer (dead is dead), but I would choose the .308 if bear or anything bigger than deer were on my list.
All else being equal (and it almost never is) bigger bullets tend to work better.
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