Ideal Barrel Length

[Polar Express]

I was going to put this in a different thread, but decided it would likely be better to begin a seperate one instead.



In the following calibers, what barrel lengths offer the most bullet energy at distance for the greatest varitey of loads and bullet weights?

.308

.300 Win Mag


If I'm willing to spend the $ to have the the bbl made for me, what length should I go with?

Im a bigger guy, so the extra weight/length won't be much of a concern.

thanks,

PE

 

[Shootin7.62Russian]

It would depend on the application. If you are looking for 600-1000 yard benchrest accuracy I would think the extra velocity of a 24"-26" barrel would benefit the .308 for this type of shooting, and would also benefit the 300 mag as well. I have even heard of bench rest guys using 28" barrels on the 300 mag as they burn a lot of powder and extra length helps velocity.

If you are going to stay 500 yards or less, I would think 22"-24" would be sufficient. The extra weight and length wouldn't really be worth the slight trade off in velocity.

Either way you go, bull barrels of .920 diameter are definitely the way to go. A barrel of normal contour at 24"+ would have excessive vibration and wouldn't be accurate at extreme distance. You want a really stiff barrel to control harmonics when shooting 600-1000 yards, as even slight differences in muzzle position at bullet exit will translate into erratic bullet behavior at those distances.

How far are you looking to shoot, and what kind of shooting are you doing? Will this be used for hunting, or will it be a target gun? This all play a factor in what you will need and what will benefit you. You don't want to lug a rifle built for F-class target shooting through the woods all day, and you don't want to go to a1000 yard benchrest match with a hunting rifle.

 

[cbrgator]

24" is probably ideal.

 

[jerkface11]

If the weight doesn't matter get the longest barrel possible.

 

[gvnwst]

If you are looking to shoot LR with that .308, i agree with jerkface.

 

[~z]

I shoot a 33” 300WM, it is 22# and generates quite a bit of velocity. It will launch a 175gn SMK at 3300fps excellent for long range shooting, not much fun to carry around. As has been said, it depends on your application.
~z

 

[Jim Watson]

Russian underestimates the barrel lengths common in long range shooting, but his last paragraph is the most important. The application governs.

Once upon a time, a 24" barrel was usual for standard caliber hunting rifles, 26" for magnums. The short action rounds like the .308 brought in a lot of 22" barrels.

My targets-only .308 has a 28" barrel only because a 30" would have cost more and taken longer to get.

Yes, a longer barrel will get you some free velocity, but if you go too long it is not worth it for anything but dedicated target shooting.
You can go too far the other way, too. There was an article in the Blue Press plugging a line of sniperoid rifles with 18" or shorter barrels. They were plenty accurate with "only a few MOA more elevation" required at long range. But the short barrels were large diameter and they were in big stout stocks, so they are still stubstantial guns. And I am not going to hump a 12 pound rifle in the woods no matter what its barrel length.

 

[P.B.Walsh]

I think for a .308 a 23"bbl. would be a good medium between a 26" and a 20". I have not a clue about a .300WM

Again, it depends on your application.

 

[Shootin7.62Russian]

I actually meant to write 28" or longer, and I have only been to one long range match so I only state what I have seen, and it hasn't been much in comparison to some people. Others who are more familiar with the sport will have more knowledge. Also, the application is important in deciding barrel length, so without knowing it is hard to say what "ideal" would be. Jim Watson and Z both own long range rifles, so their opinion far outweighs mine. But the application is most important in deciding barrel length.

 

[MCMXI]

I went through this decision process last year for EXACTLY those two calibers. The barrel contour is important too, or at least, can have a significant effect on barrel deflection. I ended up choosing 26" Krieger fluted barrels with the MTU contour for both. I reasoned that it's a lot easier to remove a few inches than it is to add them. I shoot 168gr and 178gr bullets out of the .308 and 208gr bullets out of the .300 Win Mag. Both barrels have a 1:10 twist and both barrels are very accurate with all three bullets. As you might expect, barrel length and weight affect the natural frequency of the barrel. Barrel deflection isn't necessarily a deal breaker since barrel whip and vibration can be accounted for ... the important thing is consistency i.e. where the muzzle is pointing when the bullet leaves.

Does anyone know the relationship between barrel length, twist rate and bullet weight? In other words, do slower barrels need more length to stabilize heavier bullets.

Some barrel deflection comparisons ...

 

[Jim Watson]

Does anyone know the relationship between barrel length, twist rate and bullet weight? In other words, do slower barrels need more length to stabilize heavier bullets.

Not in normal use.
If you have a marginally slow twist, the little bit of "free velocity" from a longer barrel might be the difference between adequate and inadequate stability. Best to avoid such a situation, there is plenty of data and experience to go by.

 

[Polar Express]

Thank you all for your replies!

The reason I left out what my use will be, was the last time I mentioned it, and asked a question about brand opinions, many tried to tell me to change calibers, not answer my question.

But, you all are very correct, the use dictates the specs. My intention for both of these rifles is hunting. I expect to do the vast majority with the .308, and when I want 'a little more' to reach for the .300 WM.

I don't want a long barrel just for the sake of a long barrel, but as long as the performance gains outweigh the hassle gains, I'll strongly consider it. But, I also recognize there will be a point where the extra length doesn't get you much, and lugging around a battleship barrel is a pain in the arse. I'm not little, so a few extra ounces is'nt going to matter as much to me as a smaller person.


At this time, I have no interest in long range target competetions. (if that changes, part of that consideration will include the potential need to use a different rifle)

PE

 

[Uncle Mike]

Hunting irons eehh... for the .308... 24" Standard or Light Magnum taper.

For the 300WM... 27"... Same taper.

The 300 can use more barrel, that is a decision you have to make, concerning maneuverability in the wood. The 300 can use every bit of 35".

The 308 is pretty much starting to burn out at 24-26", so the handling assets you will gain with the 24" tube compared to velocity lost, isn't a factor.

 

[~z]

35" WOW, I know it is only 2 more than what I have, but WOW, just seems a lot bigger...Fill er up with RL25 and look out 3500fps here we come!
~z

 

[Badger Arms]

46 Angels can dance on the head of a pin.

Barrel length is a PERSONAL decision. I prefer barrels of 22-24" for magnum calibers, 18-20" for lower-pressure, slower bullets.

All things being equal, shorter barrels of the same weight are more accurate because they are stiffer. A barrel that's too short, though, won't have enough powder burnt to be consistent in the velocity range, but I feel the cutoff for THAT would be in the 12-16" range. Shorter barrels also shoot slower and have more report, effecting how flat the trajectory is and your flinch respectively.

So, the answer is 21". That's the perfect barrel lenght. So sayeth me!

 

[lefteyedom]

For hunting
20" barrel for 308 and 24" for the 300 win mag.
A great stock and scope will help you more than couple extra inches of barrel lenght.

 

[USSR]

Does anyone know the relationship between barrel length, twist rate and bullet weight? In other words, do slower barrels need more length to stabilize heavier bullets.

1858,

Actually, the relationship involves velocity instead of barrel length. Of course, it's easier to get more velocity out of a long barrel than a short one, so I guess you could say there is an indirect relationship with barrel length. BTW, I also have a 26" Krieger MTU contour barrel on my .30-06, which is without a doubt, my favorite barrel. I had Jack flute it, which dropped a pound off so that it would balance better. What kind of velocity are you getting with the 178gr Amax's?

Don

 

[ParaElite]

I think I am going to pull out all my Precision Shooting magazines! When I shot 1000 yards (sling) with a .300 Win Mag. I used a 40XB which is under 12 lbs. even with a 27.25 inch 1X10 twist barrel. I was using a Unertl externally adjustable scope. It near pounded me to death. I was loading SMK 190 grain bullets with 79.5 grains of H1000. 80 grains was a might too hot. Muzzle velocity was just under 3000 fts.
For .308s I would use at least 22 inch 1X10 twist barrel and 175 grain at least. Unless you are shooting Palma which restricts bullet use to 155 grainers and a 1X11 or so twist and a 28-30 inch barrel.
I am seriously thinking of getting into the smaller caliber bullets now that I am older and want to use things like bipods. I am looking into the 6.5 Grendel and the 6mmAR (turbo or turbo + 40 Imp).
I have no idea what hunters haul around. However, I was in the army and hauled around all manner of weighty ordinance. These days, if I think of hauling around anything, I think light weight and handy with less recoil and "smaller" calibers.

 

[rangerruck]

I personally, like a 26 to 28 inch bbl; bull bbl type, medium/heavy contour.

 

[gvnwst]

I am looking into the 6.5 Grendel and the 6mmAR (turbo or turbo + 40 Imp).

For a 6mm round, while the 6mmAR is great (it was nice and accurate for me) I prefer the 6mmBR or BRX. The brass is more commen, cheaper, and you can still get Laupa. And if you want a AR, there are companies that make a BR upper.

 

[jerkface11]

A barrel that's too short, though, won't have enough powder burnt to be consistent in the velocity range

All the powder is burnt in the first two or three inches of barrel.

 

[P.B.Walsh]

For hunting, 26" in your favorite contour is AT MOST all that you need, I have no idea what target shooters use.

 

[USSR]

...I shot 1000 yards (sling) with a .300 Win Mag. I used a 40XB which is under 12 lbs. even with a 27.25 inch 1X10 twist barrel. I was using a Unertl externally adjustable scope. It near pounded me to death.

I'll bet it did. My .30-06 tactical rifle weighs 16 lbs. and drives 190SMK's at 2900fps with 60.8gr of RL22, and at the end of a prone match, I know I've been shooting a heavy load. My next build was a 6.5x55, and it's a pussycat to shoot and shoots flatter to boot.

Don

 

[EdLaver]

My 20" Remington SPS Tactical .308 does just fine out to 600 yards...

 

[MTMilitiaman]

From a .308, with no concern given to rifle size or weight, I could see going with a 26 inch barrel with a 1:10 twist to stabilize bullets of 175 to 190 gr. But the .308 case is relatively small and efficient. It does well with barrels down to 16 inches and in a portable package is well served with an 18 inch barrel. You could probably go with a barrel longer than 26 inches without seeing a loss in velocity, but any gain you experienced is probably going to be pretty small. So for optimal performance from a full-size set up, a barrel length of 22 to 26 inches makes the most sense, IMO.

A longer barrel makes a lot more sense with the .300 Win. It's less efficient but has enough capacity to deal with a healthy dose of some of today's slower burning propellants. I don't think a barrel length of less than 26 inches on a .300 Win intended for long range shooting or ballistic performance makes any sense. If I was setting a rig up around the .300 for 1200 to 1500 yard steel plates and paper, it would probably have a heavy contour barrel of 27 to 28 inches on it, with a fast enough twist to stabilize a long HPBT of 200 to 220 grs--something like the 220 gr SMK or Hornady's 208 gr Amax. The .300 has the capacity to drive either of these high BC bullets at over 2800 fps, but is going to do best with a fairly long tube. You could probably see usable ballistic gains going up to a 30 or 32 inch barrel, if you were so inclined.

My dad has a custom .338 RUM based on a M700 LA with a 30 inch Lilja #5 on it. Without even touching max listed loads, we watched 250 gr SMK chrono at over 3100 fps. Some of today's modern propellants have slow burn rates that will help achieve never before seen velocities from some of the more expansive cases available, but they need barrel length to do it. This is part of the reason I am a big fan of barrel length for most applications. I certainly think people should be getting as much of it as is practical for their use. For example, I prefer 26 inch tubes on magnum sporters and 24 inch tubes on non-magnum sporters. I don't see any reason for a heavy-barreled "beanfield" type rifle chambered for a magnum cartridge to not have a barrel of at least 26 inches, with 28 inches being even better. But of course, that is personal preference. The hunting I do is usually in country open enough to not have to worry about a little loss in handiness, and to take advantage of an extra 30 to 50 fps per inch of additional tube.