>308 Barrel Length

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by ernierod, Feb 3, 2010.

  1. ernierod

    ernierod Member

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    I am considering a .308 Winchester for informal target and bench rest shooting.Everything else being equal-does a 20" bbl offer better (generally speaking) accuracy over a 24/26" bbl?? Any advantage of a barrel with 5R rifling?? Any advantages with cut rifling over button rifling. Thanks for help. Erod
     
    Last edited: Feb 9, 2010
  2. J E Custom

    J E Custom Well-Known Member

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    If you are looking for a light weight rifle the 20" barrel will be fine. But for targets
    out to 600 to a 1000 yards. a 26" heavy barrel will do better.(Some where around
    a Sendero taper or heaver).

    The 308 can use the extra velocity with the bigger bullets (168+grs) and a 26 to 28"
    barrel will work best.

    As to the barrel type and rifling , Any good custom barrel will work, and rifling (Cut or button
    with 3,4,5,6 and 8 grooves ) will shoot great as long as the smith does his part,

    6 and 8 grooves are normally preferred for target bullets because of jacket thickness but
    the others will work.

    I hope this helps.

    J E CUSTOM
     

  3. Michael Eichele

    Michael Eichele Well-Known Member

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    I totally agree with JE on this one.

    26"+ may not be the best choice for benchrest competition but is for 600-1000 yard match shooting.

    I have seen BR quality accuracy out of all my 26" 308 barrels. None have offered BR accuracy with my hunting loads every day but then again, they were developed with high BC bullets at max velocity potential utilizing hunting weight rifles. BR accuracy being .150 or better.

    With different bullets and lower velocities and more tedious loading tecniques while utilizing a heavier platform, I am pretty sure I could have seen .15 MOA groups more often than not with any of my 308's other than 1 wby I had which was turd.
     
  4. Bart B

    Bart B Well-Known Member

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    I'm not convinced barrel length has much to do with accuracy for the .308 Win. As long as it's long enough to get small velocity spreads for the powder used and long enough to get the bullet out fast enough for the rifling twist rate to stabilize it properly, great accuracy will prevail.

    One issue with groove count as seen by top competitive shooters using wide ranges of bullet weights. Lighter bullets, such as 135 to 155 grains, tend to shoot more accurate from 4 groove barrels than 5 or 6 grooved ones. Why? I've no idea. Bullets heavier than 160 grains seem to shoot well in any groove count.
     
  5. brimiy

    brimiy Active Member

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    You did not say what type of target shooting you will be doing. A longer barrel may not be more accurate than a shorter barrel, but if your target shooting will include offhand shooting, a longer barrel may be easier to hold steadier than a shorter barrel. My suggestion would be to go to a shooting range and see what equipment they are using for the type of shooting you are interested in. Ask them questions about their equipment and why they are using that type of equipment. Most shooters are happy to talk about their shooting and their equipment. When you do get your rifle, you will probably be shooting alongside these very same shooter. Good luck and have fun.
     
  6. Kiwi Nate

    Kiwi Nate Well-Known Member

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    I shoot a 20" barreled .308 TM700 Tactical. This is my goat culling/ dog tucker rifle and light recoiling back up rifle for hunting clients as an alternative to the 7mm Magnums.

    Pro's of the 20" barrel.
    Portability
    Achieves 2840fps with 150 grain bullets.
    Achieves 2660fps with 168 grain bullets.
    Achieves between .250 and .4" groups at 100 yards with full power loads.

    Cons.
    Loss of sight picture during recoil.
    Upper end of recoil for newbies with full power loads.
    I find the recoil acceptable but feel there is no need for it when a 24"-26" barrel would tame it right down.
    Would be nice to get the 168 grain bullets shooting 140fps faster from a 24" barrel or 200fps faster from a 26" barrel (using Varget rather than the faster powders which work well in the 20" barrel).

    For target work, if I wanted to stick with a 20" barrel, I would perhaps adopt a suppressor to dampen recoil.
     
  7. Kevin Thomas

    Kevin Thomas Well-Known Member

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    I'm with Brimiy here. Need to know what sort of target shooting you're doing with this one to give you good advice. If you're into Palma shooting, a 29"-30" is pretty much required to get the velocity you need to stay supersonic @ 1,000 with a 155 grain bullet. If you're shooting across the course, a 26" barrel should be about right. The offhand and rapids dictate that balance be taken into consideration, and this is pretty much the norm among most shooters. Using a 26" barrel at 1,000 isn't a problem as long as you are using 190s or 200s (not an option for the Palma mentioned earlier), so yes, the type of shooting makes a huge difference.

    Someone suggested that you go spend some time on the range with folks who are shooting they sort of competition you want to engage in. That's great advice. I'm sure most will be more than happy to tell you their likes and dislikes, and you'll be able to make a much more informed decision.

    Kevin Thomas
    Lapua USA
     
  8. ernierod

    ernierod Member

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    Thanks people for all the good advice. I will be shooting up to and occasionally 1,000 yds. I am thinking Remington 700. Will have a choice between SPS/26"/Heavy bbl-1:12 twist OR Rem 700SS Milspec 5R type rifling-24"-1:11.25 twist. I am aware that, most likely, the 1:10/1:11.25 twist will handle heavier bullets better than the 1:12 twist bbl but I am a beginner in LR shooting and don't really know how important heavier bullets are to the long range-(700+ yards) shooting in the accuracy department.Thanks for opinions. Erod
     
    Last edited: Feb 9, 2010
  9. tackb

    tackb Well-Known Member

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    I love my 20'' custom remmy , i get 2650 out of 168 grain amax's over varget and it will shoot 1/2 inch all day if i do my part ! i'd personally not bother with an extra couple of inches for the small gain in velocity but thats just my opinion?

    Russ
     
  10. Bart B

    Bart B Well-Known Member

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    Note that when the military teams used their M14's and M1's in 7.62 NATO, handloads with 180 grain Sierra's shot very accuate at long range from their 22 and 24 inch barrels. And Sierra 190's from M1's 24 inch shot just about as accurate as the best bolt gun's with 26 inch barrels.

    Bullet quality's darned important for best long range accuracy. Even though weight and shape may all be perfect, the slightest imbalance due to jacket thickness and core metalurgy will cause inaccuracies.

    Best example of what "perfectly balanced" bullets can do was back in the early 1970's. A tool and die machinist made some collets to match the ogive and body dimensions of Lapua 185-gr. rebated base FMJ match bullets. With the collet hucked in a Dremel Moto Tool with an ampmeter connected in line with the power cord, bullets were spun at 30,000 rpm. Those with perfect balance used the least amount of current to spin the tool's motor. Slightly unbalanced ones drew more current as the put and extra load on the motor's bearings from centrifugal force that had to be overcome. A few bullets were so unbalanced they flew out of the collet and bounced off the walls and ceiling. That may have explained why 2 or 3 bullets out of a box of those Lapua's shot 9's instead of X's.

    Loading several dozen perfect ones in full length sized .308 Win. cases seated out to touch the lands, they were fired in a wood stocked Win. Model 70 with a 26-inch Hart barrel clamped at butt and forend in a machine rest. Several 10-shot groups were fired at 600 yards. They ranged from 1.5 inches down to .7 inch. Few, if any, 600 yard benchrest aggregates are that small.
     
  11. Kevin Thomas

    Kevin Thomas Well-Known Member

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    Just a quick addition here; the 11.25 would be the way to go if you're going to run the heavier bullets. The 168s mentioned will work just fine out to around 600 yards, but won't stay supersonic out to 1,000. They run out of gas between 800-900 yards in a 308. The 175s will stay supersonic out that far if they're driven to about 2,640 fps, which is what LC runs the M118LR (which uses this bullet) Match ammo. The 1x12s will handle everything up to and including the 190s, but they're starting to get a bit marginal at that point.

    The old style 180 was a great bullet in the M1 and M14, but Sierra discontinued this bullet close to 20 years ago. They replaced it with a short-boat tailed 180 MK that is totally useless, and also won't stay supersonic at 1,000. Ironic, since this was pretty much the only reason for being for that bullet. The AMU continued to buy special runs of those old-style bullets for several years afterwards, until the ARs took the game over and the M14s disappeared altogether.

    Lastly, do not EVER run 190s in either the M1 or M14s. You'll damage the gun, even if the loads are perfectly safe and well within pressure limits. The 175s or 180s are the heaviest that these should ever be fed. Otherwise, you'll wind up replacing op rods, which aren't gettin' any cheaper these days. These guns simply aren't designed to use the heavier bullets, and are balanced for bullets in the 150-175 grain range.

    Hope that helps,

    Kevin Thomas
    Lapua USA
     
  12. Bart B

    Bart B Well-Known Member

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    Good info on twist for heavier bullets in the .308. Most of the matches were won with and records set doing it with 26 inch barrels in .308 Win. had 1:11 twist. I sure wish Al Hauser of Hart Barrels was still around to make those tack drivers.

    I've still got a 1000-bullet box of the new short-tailed .308 caliber 180-gr. HPMK "standards" we got from Martin Hull. They've shot great at 1000 yards from my 26-inch 1:11 barrels at 1600 feet altitude. I don't know how they would do at Perry at aboiut 600 feet up in the air. I've heard that the new 180's weren't as good at long range as the old ones, but haven't seen it myself.

    Folks might be interested in learning that the USN and USAF Rifle Teams shooting M1's rebarreled to 7.62 NATO pulled bullets and powder from M118 LC match ammo then replaced 'em with 44 grains of IMR4350 and a Sierra 190 HPMK. The way the match conditioning shops smith's rebuilt the Garands and fitted their op rods, no problems occured. I've shot 1 to 2 thousand of them in each of the three Garand barrels I wore out. That's in addition to a thousand or so of M80 ball ammo whose 147-gr. bullet was directly replaced with a Sierra 168 for each barrel. Both loads were both hot and the most accurate short and long range loads our Garands shot. But no rifle suffered from it. Even magnifluxed some of the receivers checking for cracks at times but none were seen.

    But I caution folks with Garands, don't use these loads unless one of only two people left over from those shops and still building them did all the right stuff on yours.
     
    Last edited: Feb 10, 2010
  13. trebark

    trebark Well-Known Member

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    Rem700SPSV in 308 is a good starting point. Here's the write-up on mine....

    http://www.longrangehunting.com/forums/f53/my-308-1k-rifle-evolution-continues-43510/

    Others have said it and I agree that for long range shooting you should be looking at the 175+ grain bullets. Although I've seen some guys get the 168's to 1000, I've seen just as many key-hole the target (bullet started to tumble) at 1000 yards.
     
  14. davkrat

    davkrat Well-Known Member

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    I'm confused running the numbers on a 155 grain bullet (BC .500 or so) around 2800 fps still stays super sonic at 1000 yards. I must confess I have never even attempted a 1000 yard shot but the computer models make it seem like a easily obtainable MZ in a 24" barrel would be more than enough with that size bullet.