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Old February 26, 2013, 12:58 PM   #1
new_scopeshooter
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rem 700 .308win

Hello! I am debating on cutting down the barrel on my 700. It is currently 26inches. I have read that alot of long range guys go as short as 20inches. It has a 1/12 twist. What are your opinions.
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Old February 26, 2013, 02:07 PM   #2
GeauxTide
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Don't go past 22". This cartridge has a great bore/capacity ratio, so you'll get max velocity with the 22".
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Old February 26, 2013, 02:36 PM   #3
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What problem do you think this will solve?
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Old February 26, 2013, 02:49 PM   #4
jmr40
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Here is a good read

http://www.tacticaloperations.com/SWATbarrel/

It really depends on the gun and the use. Some go as short as 16" with acceptable results. I prefer 20" as a minimum, and it isn't just about velocity loss. Shorter than 20" and muzzle blast starts to be a problem and depending on the gun the balance is all wrong.

You will lose some speed going down to 20" from 26", but probably less than 100 fps. Unless you are really pushing the limits of 308 range I don't think you will ever notice the difference.
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Old February 26, 2013, 07:57 PM   #5
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I prefer 24" out of a .308 barrel. 20" is a little on the short side if you are thinking about getting into the long range game.

However, 26" really is not that bad. Why are you wanting to cut it down?
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Old February 27, 2013, 06:43 AM   #6
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Really was just looking for a better balance. Im running a HS Precision stock with Leupold mk 4 ert 4.5-14x50. Looking at 1000 yard max shots. In the spring I will be attending a long range school here in ohio. I also would like some input on muzzle breaks. Every manufacturer says thiers is the best. Which one to get???? O the cost of long range!!!
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Old February 27, 2013, 08:24 AM   #7
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Folks shooting the best scores in long range competition use barrels from 26 to 32 inches. With the .308 Win. case and powders used for best performance, they all increase muzzle velocity up through 34 inches; probably more. Palma rifles have 30 inch barrels to get 155-gr. bullets out the muzzle at about 3000 fps to stay supersonic through 1000 yards; shorter barrels won't do it. A 22 inch .308 Win. barrel is barely going to do it at normal, safe peak pressures at 52,000 cup (60,000 psi) with 175 or 180 grain bullets.

Yes, some folks do use 20 inch barrels; AR10's chambered for the .308 Win. are allowed in NRA service rifle competition. The US Army does but only because folks shooting 7.62 NATO Garands were producing better scores in 1000-yard matches than their 5.56 NATO service rifles and the US Army Advanced Marksmanship Unit didn't have anything to compete with those Garands; they got the NRA to allow AR10's to be used. The load used in them to shoot Berger 185-gr. bullets was about the same as proof loads close to the 65,000 cup (80,000 psi) range. It was the only way that short barrel could produce the muzzle velocity needed. Military teams had previously used such loads in their M14's and 7.62 M1's with 180's and 190's, but those rifles could handle that pressure with ease and members didn't reload fired cases using them.

I discourage folks using muzzle "brakes" as rifles with them are not allowed in competition and may be so in training classes, too. To say nothing about their oft time issues of robbing accuracy. Especially when it's raining. Muzzzle brakes are not needed on .308 Win. rifles; unless they weigh less than 2, maybe 3 pounds.

GeauxTide, what's your reasoning behind this comment: This cartridge has a great bore/capacity ratio, so you'll get max velocity with the 22".? How do you calculate that ratio?
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Last edited by Bart B.; February 27, 2013 at 05:34 PM.
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Old February 27, 2013, 09:15 AM   #8
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jmr40' link http://www.tacticaloperations.com/SWATbarrel/ is both interesting and typical of what lots of published results of rifle tests say. But like so many of them, it doesn't tell the whole story and some of the data is questionable. Examples:

Quote:
Going to an 18-inch barrel doesn't adversely effect the accuracy of the rifle. Tac Ops has achieved incredible accuracy with the shorter barrels. The 18-inch barreled Tango 51 rifles will still shoot sub-1/4 MOA.

The accuracy of the Tango 51 isn't hampered by the shorter barrel. While at the range with the Tango 51 we were consistently getting sub-1/4 MOA accuracy at longer ranges? Well, the shorter barrel doesn't hamper longer range accuracy either.

As I mentioned in my article on the Tango 51, San Fernando (CA) PD Special Response Team long rifle marksman Chris Colelli once fired a 3-shot sub-1/4-inch group at the article appeared, Colelli fired a 3-shot group from the rifle at 700 yards that measured just under 2 inches center to center. The group, which was witnessed by several credible spotters, was shot off of a bipod with one small sandbag.
What's the size of the biggest groups fired? Are they too egotistical to publish that data? They obviously don't want folks to think about the larger ones even though that 2-inch 3-shot group was probably by far the smallest one shot and all the others were larger; much larger.

The very best benchrest rifles do not consistently getting sub-1/4 MOA accuracy at longer ranges; it's more like sub 3/4 MOA which is what their group agg's prove.

Quote:
Shorter barrels are actually often more accurate than their longer counterparts. A rifle barrel is a cantilevered beam and as such they sag. More sag results in more whip and vibration as the bullet travels down the bore. Barrel sag induces longitudinal stress that can cause stringing of shots. Using a shorter, heavier barrel minimizes reduces stress and accuracy-robbing barrel vibration. A shorter barrel is stiffer and vibrates at a less.

Barrel length and contour determines the relative "stiffness" of a barrel, i.e., how much a barrel will tend to vibrate. Shorter barrels generally have oscillations of smaller amplitude. than longer barrels. Thicker barrels generally have fewer vibration nodes than slimmer barrels. The ringing frequency of a thicker barrel is higher and the oscillations are of a smaller amplitude and of a shorter duration. This equates to less barrel motion at the muzzle. The use of a shorter barrel also allows the use of a heavier contour without making the rifle unwieldy.

The use of a heavier contour tends to provide less variation between a cold shot and any subsequent follow-up shots. Barrels expand as they heat up. As the barrel expands any stress on or in the barrel will cause stringing of the shots. Bore expansion results in an increase in group size. Heavier barrels tend to be more consistent because they take longer to heat up.
What they don't mention is that any given barrel vibrates exactly the same for each shot fired for a given load. A different load makes it wiggle more or less, but the vibration frequency's the same.

If the bore's enlargement from normal to bigger as the barrel gets hot starting out cold, then nobody would be able to shoot a few dozen shots under 2 inches at 600 yards. That's been done but with bullets sorted to use only the perfectly balanced ones so the barrel could be tested for accuracy going from cold to very, very hot. They don't know what they're talking about. I think their problem was poorly fitted barrels or barrels not stress relieved properly.

Quote:
During the development of the Tango 51, Tac Ops took a standard 26-inch barrel and cut it down to 18 inches in one-inch increments. Between 10 to 20 rounds were fired at each invrement. They found that a 20-inch barrel provides for a complete propellant burn and no velocity loss when using Federal Match 168-grain BTHP, a cartridge that has become something of a law enforcement standard. Going to an 18-inch barrel only resulted in a loss of 32 feet per second (fps).
Too many people have done similar tests, including SAAMI, and with bullets leaving in the 2500 to 3000 fps range muzzle velocity drops by 20 to 25 fps per inch the barrel's shortened. Maybe they used ammo with "barrel length sensors" in it so the powder would keep the same pressure requirements to push the bullet out at nearly the same velocity by changing the powder's burn properties. That claim's one worth "dishonorable mention" in my opinion.
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Last edited by Bart B.; February 27, 2013 at 12:48 PM.
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Old February 27, 2013, 09:25 AM   #9
jmr40
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Quote:
GeauxTide, what's your reasoning behind this comment: Don't go past 22". This cartridge has a great bore/capacity ratio, so you'll get max velocity with the 22"
If I read that right he is suggesing not going SHORTER than 22".


Shooting at 1,000 yards was not mentioned in the OP. At that range the extra barrel length is helpful. For a general purpose hunting rifle shot at closer ranges, say 400 or less then a shorter barrel is much less of a handicap. My original advice was with that use in mind.
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Old February 27, 2013, 12:18 PM   #10
allaroundhunter
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For 1,000 yard shooting I would keep the 26" barrel.... If you cut it down do not go less than 24". You won't be able to get the velocities necessary to keep the bullet stable out to 1,000 yards consistently; especially if you don't handload.
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Old February 27, 2013, 12:46 PM   #11
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jmr40, I was referring to his great bore/capacity ratio comment and 22" for max velocity. Thanks for commenting on it; I edited my earlier post.
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Old February 28, 2013, 11:03 AM   #12
new_scopeshooter
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Thanks for the advice. I will not be shooting in competition. This will be a hunting rifle with 1000 yard range trips.. how exactly does a muzzle break hinder accuracy?
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