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>308 Barrel Length

 
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  #8  
Old 02-09-2010, 11:48 AM
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Re: >308 Barrel Length

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 by ernierod; 02-09-2010 at 11:51 AM.
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  #9  
Old 02-09-2010, 11:56 AM
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Re: >308 Barrel Length

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
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  #10  
Old 02-09-2010, 11:59 AM
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Re: >308 Barrel Length

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.
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  #11  
Old 02-09-2010, 02:57 PM
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Re: >308 Barrel Length

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
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  #12  
Old 02-10-2010, 07:09 PM
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Re: >308 Barrel Length

Quote:
Originally Posted by Kevin Thomas View Post
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.
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 by Bart B; 02-10-2010 at 07:56 PM.
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  #13  
Old 02-10-2010, 07:58 PM
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Re: >308 Barrel Length

Quote:
Originally Posted by ernierod View Post
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
Rem700SPSV in 308 is a good starting point. Here's the write-up on mine....

My 308 1k Rifle - The Evolution Continues!

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.
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  #14  
Old 05-31-2010, 11:06 PM
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Posts: 529
Re: >308 Barrel Length

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.
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