Will shortening a 24" 308 barrel by 2" change the harmonics and affect accuracy?

V

VaniB

New member
Will shortening a 24" 308 barrel by 2" change the harmonics and affect accuracy?

Though a DPMS Semi-auto .308 is not what most folks on these forums discuss, I think the issue and concern remains the same whether it be a Remington 700 barrel, or a DPMS barrel;

I have spent much time and effort to find the bullet and powder load to get this 24" rifle to shoot a one hole group.
Am I risking losing the current tight groups that I get with the specific load if I have my smith shorten the barrel 2" ??

I am also considering having him turn the barrel down to a lighter contour and was wondering if this will change the internal stress of the steel and also cause accuracy concerns.
 
Yes all these things will change your group sizes. Turning will change the vibration of the barrel. Shortening will not only change the harmonics of the barrel in a holly unpredictable way but you will also be giveing up an accuate load and crown. Why do you wish to change the length.
 
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why not just replace it with a benchrest rifle ? put a kreiger bbl on it and try again ? an ar is not a benchrest gun , so why expect or try for br results ?
do you have a nice flat forend ? a tight neck ? the twist for the bullet ?

still loading from a mag ? 4lb trigger ???

what are you trying to do ?
( if you do not know , i have a 308 (308 win br) ar10(t). its small group is 0.116" it ags under .2...easy, but it aint no semi auto......krieger 1/15 twist, 134gr BIB bullets...)

mike in co
 
Hmmm.... now I'm wondering if all my effort and time spent handloading to find the most accurate load will be all for naught if I proceed with altering the barrel dimensions. :confused:

I wanted to shorten the barrel, add a 4 sided rail and a flash hider, as well as make this heavy bull barrel a bit lighter by having some metal removed over the length of it. My smith says there's plenty of metal he can remove.

Mike,
It's just a matter of personal preference and how I want to trick-out the rifle to look and handle. The rifle currently shoots 3/4" and I'm quite satisfied with that. Not looking for benchrest. Just wanted to change the cosmetics and feel of it.
 
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ok...that is possible, but you will likely have to retune your loads for the new bbl characteristics.....i'd skip the lightening.... get a great crown and go for it.
 
22"

I'm guessing it would probably shoot better.

My LTR is 22" and shoots great. Although the 175gr shoot better than the 168's.

Does it have a flash suppressor? I'm thinking probably not.

Just hella curious..

:)
 
VaniB said:
Am I risking losing the current tight groups that I get with the specific load if I have my smith shorten the barrel 2" ??

I am also considering having him turn the barrel down to a lighter contour and was wondering if this will change the internal stress of the steel and also cause accuracy concerns.
Click to expand...

I think you might find this article very interesting (there is a bunch of good stuff on that web page).

http://www.varmintal.net/amode.htm

After reading it, I'd have to say the answer is not only "yes, it wll have an effect", it will absolutely definitely for sure have an effect, and the effect can't really be predicted in advance.

In short, it will be a completely different barrel dynamicallly, and you will have to make friends with it all over again. If the same load shoots best in it, that would be pure luck.

Fitch
 
Thanks guys. I have this question posted in a couple of other websights as well. But, I've had two competition shooters at one foum say that they have done this and have noticed no change. One of these two guys recontoured the whole length of the barrel with different dimensions.

But, the consensus is 50/50, and I'm under the impression that it's a crap shoot and it can go either way. I guess every barrel has it's own personality and there are just too many variables for this to be predictable.
 
If by change you mean shortening....

No it should not. As a matter of fact, it should reduce effects of harmonics since you will be making it more rigid. I have a 30-06 that was a 24-inch and shot MOA, cut it down to 17 inches, now it is a 0.6 MOA gun. Had similar results with a 260 Rem.
 
missloumudcat said:
No it should not. As a matter of fact, it should reduce effects of harmonics since you will be making it more rigid. I have a 30-06 that was a 24-inch and shot MOA, cut it down to 17 inches, now it is a 0.6 MOA gun. Had similar results with a 260 Rem.
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hmmm from moa to .6 moa...and that is not a change ???
he did not say bad or good, he said change
 
missloumudcat said:
No it should not. As a matter of fact, it should reduce effects of harmonics since you will be making it more rigid. I have a 30-06 that was a 24-inch and shot MOA, cut it down to 17 inches, now it is a 0.6 MOA gun. Had similar results with a 260 Rem.
Click to expand...

Was the improvement found with the benefit of your being able to use your same loads or cartridges?...or did you have to start using different ammo?

Sure a change for the better is welcome, if there's going to be any change at all. But my main concern is being able to use the same accurate handloads that took me a lot of time and trouble to find.
 
haha, yes change for the better

I am achieving better results using the same premium factory ammo, no handloads. I must mention a good recessed target crown was added also.

I first did this not on a whim, but I needed to lighten up my rem 700 30-06 and make it better balanced. It initially had 24inch long, 1-inch diameter barrel. cutting it back to 17inches took off nearly 1.5 pounds off the front end, made it much more balanced and easier to use in the woods.

Since then, I have found articles on it. GPS out of Arizona has conducted field test with 308's they have cut down the barrels on. They are shooting out to 600 to 1000 yards (much farther than I am with my '06) and show no decrease in benefits. Ya'll check it out -good reading.

http://www.sniperschool.com/barrel-length-revisited/

Jim
 
one very seldom finds a negative on something one is marketing.......
 
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