Gunsmithing Barrel length vs accuracy

Bryschopper

Bryschopper

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Minuteman
Dec 30, 2009
28
0
54
FL
#1
I have a 308 with a 26" barrel and wanted to know how much could I remove without affecting accuracy for long range shooting. I was thinking of taking it down to 24" and threading it 5/8-24, then adding a muzzle brake. I'm currently using Sierra 175gr HPBT match with 43gr Varget and the gun is shooting awesome, I would hate to ruin a good thing, but would really like to shorten it up. I know that I will lose a little velocity. What distances are you guys shooting with what barrel lengths?
Thanks
IMG_2475.jpg
 
#7
Re: Barrel length vs accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kane308</div><div class="ubbcode-body">I'm getting 1674fps out of my 20" with 175SMKs with 45.5 gr of Varget. It was accurate out to 1200 </div></div>
I think you mean 2,674fps, right?

Keith
 
#8
Re: Barrel length vs accuracy

accuracy is generally improved by shortening a barrel, unless the crown job is jacked up. The shorter barrels are stiffer. You will typically lose some velocity requiring more elevation to get to 1K, but the accuracy should improve. In a .308 20" seems to be the least you can go without marginal performance, though some are doing less with a tight bore. At higher elevations you can get a little more out of a load as well.

Dave
 
#9
Re: Barrel length vs accuracy

I was thinking that he was using the powder measure for my 5.56 ammo, I figured he meant 2674 FPS. Anyways I'm looking forward to making her shorter, I do have one question, using a 20 moa base would I be able to zero at 100 yards or would I have to zero at say 300. I would like to set up for long range, but the longest range I have access to is 600 and soon to be 800. I have my scope zeroed at 100 yds, I have noticed that I have 4 revs under my zero, which works out to 24 moa that I'm not using. The Millett scope that I'm have has 6 rotations for a total of 48 moa adjustment. I guess I just answered my question with a 20 moa base I would have -4 moa under zero to play with and +44 moa above. My barrel at it's current length 26" would require about 30 moa to reach 1000 yards, When I cut it down I figured about 40 moa to get out there. I'm starting to see the light at the end of the tunnel. This stuff is finally making sense. I'm rather new to this style of shooting, let me apologize up front, I am here to learn, thanks for your input.
 
#10
Re: Barrel length vs accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DebosDave ©</div><div class="ubbcode-body">accuracy is generally improved by shortening a barrel, unless the crown job is jacked up. The shorter barrels are stiffer. You will typically lose some velocity requiring more elevation to get to 1K, but the accuracy should improve. In a .308 20" seems to be the least you can go without marginal performance, though some are doing less with a tight bore. At higher elevations you can get a little more out of a load as well.

Dave </div></div>

There are a lot of factors that influence accuracy and many are hard to test. If you shoot or watch long range matches (bench rest where small group size and score wins) it is very rare if they are won or records set with short barrels. Short range is a different game but most rifles are configured to weight 10.5 lbs with scope so a short stiff barrel is the only viable option however this question was about long range shooting.

If folks are getting better accuracy out of shortening the barrel, my guess is the new/fresh crown caused the accuracy gain!
 
#11
Re: Barrel length vs accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rodbolt</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DebosDave ©</div><div class="ubbcode-body">accuracy is generally improved by shortening a barrel, unless the crown job is jacked up. The shorter barrels are stiffer. You will typically lose some velocity requiring more elevation to get to 1K, but the accuracy should improve. In a .308 20" seems to be the least you can go without marginal performance, though some are doing less with a tight bore. At higher elevations you can get a little more out of a load as well.

Dave </div></div>

There are a lot of factors that influence accuracy and many are hard to test. If you shoot or watch long range matches (bench rest where small group size and score wins) it is very rare if they are won or records set with short barrels. Short range is a different game but most rifles are configured to weight 10.5 lbs with scope so a short stiff barrel is the only viable option however this question was about long range shooting.

If folks are getting better accuracy out of shortening the barrel, my guess is the new/fresh crown caused the accuracy gain!</div></div>

I don't think it is that hard to test the theory, and I don't think there is much myth about it. Shorter is stiffer, stiffer is more accurate. You can have a longer accurate barrel but you have to go heavier to do it. In the same contour the shorter the barrel the more accurate all else being the same. There is a reason they pick 20" heavy over 24" lighter contour for bench guns, Less Whip. If length and/or velocity was king they would be going longer and fluting barrels to make weight in the bench game...

the only trade off for shortening a barrel is velocity loss. Velocity has little to do with accuracy. It does affect effective range and subsonic distance, but not accuracy. A rule of thumb is the heaviest shortest tube that will get you where you need to be. It is a balance of desired distance, weight, and accuracy.

Dave
 
#12
Re: Barrel length vs accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DebosDave ©</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rodbolt</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DebosDave ©</div><div class="ubbcode-body">accuracy is generally improved by shortening a barrel, unless the crown job is jacked up. The shorter barrels are stiffer. You will typically lose some velocity requiring more elevation to get to 1K, but the accuracy should improve. In a .308 20" seems to be the least you can go without marginal performance, though some are doing less with a tight bore. At higher elevations you can get a little more out of a load as well.

Dave </div></div>

There are a lot of factors that influence accuracy and many are hard to test. If you shoot or watch long range matches (bench rest where small group size and score wins) it is very rare if they are won or records set with short barrels. Short range is a different game but most rifles are configured to weight 10.5 lbs with scope so a short stiff barrel is the only viable option however this question was about long range shooting.

If folks are getting better accuracy out of shortening the barrel, my guess is the new/fresh crown caused the accuracy gain!</div></div>

I don't think it is that hard to test the theory, and I don't think there is much myth about it. Shorter is stiffer, stiffer is more accurate. You can have a longer accurate barrel but you have to go heavier to do it. In the same contour the shorter the barrel the more accurate all else being the same. There is a reason they pick 20" heavy over 24" lighter contour for bench guns, Less Whip. If length and/or velocity was king they would be going longer and fluting barrels to make weight in the bench game...

the only trade off for shortening a barrel is velocity loss. Velocity has little to do with accuracy. It does affect effective range and subsonic distance, but not accuracy. A rule of thumb is the heaviest shortest tube that will get you where you need to be. It is a balance of desired distance, weight, and accuracy.

Dave</div></div>

Doesn't that beg the question, How accurate do you want to be at X range? at X velocity? And, I think velocity does definitely have an affect on accuracy. Why do some bullets (155 Scenars) shoot much better at higher velocities at near maximum pressures?

Sorry I don't follow your logic of shorter is more accurate (I do understand the shorter=rigidity argument). But I think it is a bit more complicated than that, don't you? Sure, Lowlight's 18.5 inch barrel can ring 1K steel at moa or sub moa all day long. But most people are not running custom actions and custom barrels that can perform equally, much less factoring in shooter error or inexperience. I think it is entirely misleading encouraging novice/somewhat experienced shooters to just chop their barrels and expect to get great results. Not gonna happen.

All that aside, you probably know more than I do but I figured someone should pipe up.
 
#13
Re: Barrel length vs accuracy

There is nothing wrong with short barrel for 308. Sure a longer barrel can push those bullets a bit faster but as was stated before velocity does not translate to accuracy. Sure you need to stay supersonic out to your target distance (that transonic thing generally doesn't work out well for lighter 30 caliber bullets), but the key to accuracy at distance is consistency. Top velocities are nice for bragging rights but top velocities don't help your ES is 15+ and SD is 10+.

Remember that 308 winchester generally burns powders with fairly fast burn rates thus is blends well with shorter barrels. Benchrest and Palma shooters do a lot of things differently because it is a different environment and style of shooting. Think of it this way you wouldn't want to drag that 20 plus pound benchrest gun out hunting would you? No body does and that is because it doesn't fit the situation. Same goes for this. For practical purposes there is no need for a barrel over 20 inches on a field gun in 308 winchester.
 
#14
Re: Barrel length vs accuracy

I just compiled the best group shot with 24 of my best rifles.

The rifle I hunt with did not make the list.
It is a 270 with a 22" Pac Nor ultra light barrel.
That rifle weighs 8.9 pounds with scope, sling, and bi-pod.
It can shoot 5" 3 shot group at 500 yards.

I have all this junk to carry:
Binoculars
Range finder
GPS
Camera
Cell phone
Water
Knife
Saw
Harness for dragging the animal out

Often I climb up 1000 feet, once I climbed 3000 feet.

What does it all mean?
As a 58 year old man with a beer belly, I put my rifle on a diet.
 
#15
Re: Barrel length vs accuracy

Wow, I guess I opened up a can of worms, My reasoning behind my question was that I'm interested in shooting in two man sniper comps, I want accuracy as does everyone else, I just don't want to be running and lugging a heavy rifle if I didn't have to. I am looking for a compromise in length and weight. If it's good enough for the Marines then it will work for me.
 
#16
Re: Barrel length vs accuracy

Swan,

Just an FYI, the Gladius started out as a $1400 Reminton PSS in an AICS and I had it changed... I bought it on the Hide in the For Sale section. Sent it out and had my changes made to this 700. (Kept the stock here)

it's just a rebarreled Remington 700 with a good Bartlein Barrel... it's not a custom action, but it is a good barrel.

As well I have a 16" AR10 that shoots factory 175gr ammo to 800 yards with amazing accuracy, there is a member here who shot it one afternoon without me and had the same results, consistent hits on an 8" plate at 800 yards.

Experience does matter, but the shorter the barrels are, the more consistent they appear to be, not just by me but by a lot of people.

Also we loan our rifles out to a lot of students and all our barrels are short, 22" or less, we have no 24" 308s on the range at Rifles Only and when we rebarrel them we continually go shorter. They have absolutely no trouble as new shooters to hit what they aim at, whether a 1000 yards or in, at sea level in South Texas, using factory fare.

In 2005 the Harbinger won the ASC "dirty group" at 600 yards using factory ammo. It shot a 3.25" group at that distance under field conditions, in fact I was holding a mil of wind on the target. I didn't win the match, but won that, against a host of wind cheaters, so while experience matter, the accuracy was there in my 22" 308. Ask GAP how many people cried because they didn't want anything to do with a 22" 308, to this day it was the most complained about thing with that rifle which also had the very first Badger Bottom metal for the AICS magazine. Everyone wanted the bottom metal, no one wanted a 22" barrel... Harbinger = Remington action with good barrel.

I take opinions on short barreled 308 with a grain a salt because I see it everyday, as that is pretty much all I use... Email Clint Smith at Thunder Ranch, ask him how long his barrels are in his and Heidi's 308 that they shoot ? and he uses 168grs which I don't recommend. I am not shooting F class where I am trying to hide my desire for a 260 in a 308, so I have no need for a 28" long 308 pushing 155gr stuff at 2950fps... if I want a 260, I can just unscrew my 20" 308 barrel from my AI AW and put my 22" 260 barrel on, so why pretend with my 308.

Light is Right and and Short is Smart,
 
#17
Re: Barrel length vs accuracy

My 27" .243 is my most accurate rifle. Has a #7 barrel on it. Shot best group at the Idaho State Sniper Challenge of .250" outside to outside so that would be about .007" center to center. Also here's a 3 shot group from 2008 NorCal match at 500 yards. And before anyone says anything that was the drill, 3 shots
wink.gif

norcal_tbrc08_09.jpg


Shorter might be a little more handier and lighter as far as carry and even make it stiffer but it doesn't make it more accurate. A good barrel and gunsmith does that. My 28" 6.5 Creedmoor with Factory ammo is plenty accurate also. Old lot 5 shot on left and 10 shot new lot groups
P7080622.jpg


For a .308, I would go about 22" as it will still give you plenty of velocity for reaching out long but also make it a little lighter and handier. My .308 was at 22" until I set it back when the throat went and it shot 178 AMAX at about 2710fps and was good to 1300 yards. It runs at 20" now and that's about the shortest I would go but it's also a custom tube and they usually get better velocities than factory barrels due to better bore conditions. Velocity is about 2690fps now. Just something to think about.
 
#18
Re: Barrel length vs accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">
Light is Right and and Short is Smart, </div></div>

Short is smart LOL
smile.gif
 
#19
Re: Barrel length vs accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Swan</div><div class="ubbcode-body">

Doesn't that beg the question, How accurate do you want to be at X range? at X velocity? And, I think velocity does definitely have an affect on accuracy. Why do some bullets (155 Scenars) shoot much better at higher velocities at near maximum pressures?

Sorry I don't follow your logic of shorter is more accurate (I do understand the shorter=rigidity argument). But I think it is a bit more complicated than that, don't you? Sure, Lowlight's 18.5 inch barrel can ring 1K steel at moa or sub moa all day long. But most people are not running custom actions and custom barrels that can perform equally, much less factoring in shooter error or inexperience. I think it is entirely misleading encouraging novice/somewhat experienced shooters to just chop their barrels and expect to get great results. Not gonna happen.

All that aside, you probably know more than I do but I figured someone should pipe up.</div></div>

Yes, that is why I said it is a balance between distance and weight. You have to have enough velocity to play the game that's why I quantified my 20" statement above for 1K yards. You can do better with a tight bore or a higher elevation.

The reason a scenar flies better at higher velocities in some rifles is due to twist rates and stabilization. It isn't the velocity that makes them more or less accurate it is the stabilization.

I don't think it is any more complicated than this: Shorter barrel is stiffer, stiffer is more consistent and more accurate. To have a same stiffness barrel at a longer weight you need to increase the contour making it increasingly heavier. You definately DO trade off velocity for rigidity in similar contour barrels. SO, with each distance goal that you want to consistently shoot at, the best match is the heaviest shortest barrel you can do practically. That means for the .308 20" is a good number, then go the heaviest contour to make a reasonable weight. This is typically a Rem Varmint contour or a #7 straight taper... maybe a Light or medium Palma...

Your mileage may definately vary, but I don't think there is much arguement that shorter/stiffer is more consistent (all other variables being the same).

Dave
 
#20
Re: Barrel length vs accuracy

I will say this, velocity will give an advantage in drop and windage adjustments, but that doesn't translate to accuracy, it only translates to forgiving user error in ranging and wind calls. Just to quantify because it seems that Rob (a much better shooter than I am) is directly contradicting what I am saying, but I think he is saying something different than I am. I also tend to think that saying my most accurate rifle is 27" doesn't tell a complete story. Would 28" be more accurate? Would 26"? Perhaps this is just a hummer barrel?

Not trying to offend you Rob, as your results are tough to argue with
wink.gif
. I think at the end of the day if we all spent more time shooting and less debating what is best or not, we might all find that our skills increase enough to not get our panties so twisted over such trivial matters...
 
#21
Re: Barrel length vs accuracy

one thing to mention is cutting an oem barrel down to 20" is probably not going to have the same velocity as a quality match grade 20" barrel.

while a 20" barrel will get you to 1k, in my opinion, it is not the best choice for a dedicated 1k prone rifle. now if you want an all around rifle, it may be a good choice.
 
#22
Re: Barrel length vs accuracy

What I was saying is that saying a barrel will be more accurate because it's stiffer and shorter is just not true and I gave a couple of examples. My most accurate rifle <span style="font-weight: bold">is</span> a 27" barreled rifle and that is a fact. Complete story. Would it be as accurate a couple inches shorter? Possibly but that doesn't prove the point that shorter is more accurate. Just that it might be as accurate. Saying that a 18" barrel will be more accurate than the same barrel at 26" also doesn't tell a complete story in the same regards.

My .308 was a 24" barrel and I had it cut to 22" and had it threaded for a can. Lost a couple of FPS but same accuracy. Had it set back and a new brake for my Surefire can put on and the rifle and it's at 20", same accuracy just lost a little FPS. Lost 4" of barrel but didn't get more accurate. Shouldn't it have now that it's shorter and stiffer?

Get a good barrel and have it installed by a good smith and shot by a good shooter and it will shoot very good no matter if it's 18" or 28". That is my main point. Don't get hung up on shorter is more accurate. Shooting more and posting less will definitely help the shooter. I will agree with that.
wink.gif
 
#23
Re: Barrel length vs accuracy

Note that shorter barreled <span style="font-style: italic">rifles</span> can be more difficult for the average shooter to shoot well at longer distances.

As with everything, the best package for the task is a compromise.

My .284 build, when it arrives, will have a 25" barrel. Because for tactical comps I don't need F-class velocities, just BC enough to rule the wind.
 
#24
Re: Barrel length vs accuracy

Not sure if this was addressed because I only skimmed some of the longer responses... But does twist rate come into play when shortening a barrel? I would think that a 1:12" twisted .308 may not stabilize the more common weight bullets if you go too short. Would it be better to start out with a 1:10" or 1:11.25" or does that not matter at the length you're talking about??? Just thinking outloud...
 
#25
Re: Barrel length vs accuracy

Well Guys it's finished. I had to make a few tools to get the job done, I cut a barrel wrench out on the wire EDM, then made some oak vise jaws. She came apart real easy, It took a while indicating the barrel in true on the lathe but I wanted it dead nuts. After cutting off the excess, I turned down the barrel then threaded it 5/8-24. Finally I re-cut the crown nice and sharp with no burs, It was about 2 hours in all, I made the wrench and vise jaws yesterday. Here are some finished pics, I still plan on fluting the barrel this weekend.
IMG_2487.jpg

Homemade tools
IMG_2490.jpg

IMG_2477.jpg

The before pic
IMG_2478.jpg

IMG_2480.jpg

IMG_2486.jpg

Finished Product, I plan on making a muzzle brake next after fluting the barrel, Then a new stock on the way.
Thanks for all the input...
 
#27
Re: Barrel length vs accuracy

Well today I started on the muzzle brake, It started out as a 1.250 dia piece of 304 stainless. I turned it down and drilled and tapped the bore. Then I cut some flats on it to shed some weight. I'll cut the gas ports tomorrow. Here are some pics.
IMG_2495.jpg

IMG_2501.jpg

IMG_2505.jpg
 
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