Is there any real advantage for super long barrels?

[arghloba]

I've tossed around the idea of purchasing a DTA HTI in .375CT for about a year now. I think I will finally give in sometime next year. In the DTA SRS/HTI thread, there are some users who run 35"+ barrels on their 338LM and other cartridges. What would be the advantages (other than boost in FPS) of having that extra six inches over the included 29" barrel from the factory? Would there be any noticeable accuracy difference at 1500+? I figured with such a "short" package from the DTA rifles, you could tack on a longer barrel and still be undersized/underweight for a big bore rifle.

Anything helps.

Thanks,

 

[mdmp5]

It’s not about accuracy; it’s mostly velocity guys are after in running a long barrel. In addition, the added weight gives the rifle a bit more stability under recoil. 35” is quite long though. The velocity gain diminishes substantially once you get over 30” I think; someone correct me on this if I am wrong

 

[Ripdog28]

It’s not about accuracy; it’s mostly velocity guys are after in running a long barrel. In addition, the added weight gives the rifle a bit more stability under recoil. 35” is quite long though. The velocity gain diminishes substantially once you get over 30” I think; someone correct me on this if I am wrong

Diminishing velocity from barrel length depends on the bore diameter/powder charge/ bullet weight/design/temp/altitude and probably a few other factors.

Short stiff barrels generally provide less whip than long but less velocity also.

 

[Fig]

This article is about barrel length in the 5.56 using a NATO cartridge, but the principals apply broadly.
http://www.sadefensejournal.com/wp/?p=1093

Twist rate also figures into it:
http://bulletin.accurateshooter.com/2015/02/does-barrel-twist-rate-affect-muzzle-velocity-litz-test/


"Optimal" also changes quite a bit depending on the burn rate or the powder and the weight of the projectile. You may as well just leave out barrel whip and precision; as that introduces an entirely different set of variables that can (maybe) be dealt with in the loading.

IMHO there are no definitive answers, and each specific system/cartridge/loading must be understood on it's own.

It's not my intent to give you a bullshit, non-answer, but once you start considering all the variables it quickly becomes apparent that there are too many to even come up with a rule of thumb. Just look at the 5.56 example and testing. There is no question those results don't transfer in any way to a .308 based on case volume and weight of projectile even if you kept to the same powder. Only the principals as understood in the study would generally transfer, but those parameters are going to be far different with a different cartridge.

I think that a ton of research could be done here, but the truth of the matter is that we have a wide enough selection of powders and bullets to load cartridges that maximize efficiency of normal lengths or even abnormal barrel lengths. The bottom line is that to a point you can make a longer barrel run faster with the right loading. The longer the barrel (to a point) the faster you can make it go till you're at Retumbo/50BMG powder range for each cartridge and you run out of speed (or rather can't get any slower burning powder). I would expect that those barrels, for any but the huge caliber cartridges, would be ridiculously long and of little practical use.

My .$02.

 

[silentheart]

My barrel is longer than yours. Ask your wife if that extra 6 inch matter when she shoot your dta.

 

[buffybuster]

Pros:
Velocity is free.
Makes you're regular chambering perform like an improved variant.

Cons:
Harder to handle, if you have to move around
Barrel is not as stiff, so nodes are narrower
Potentially harder to store/transport

My rule of thumb is the longest barrel I can comfortably manage. 26" no problem, 28" makes it an unmanageable pig.... Funny how 2" makes all the difference to me.

A bullpup action allows you to run a much longer barrel for a given OAL.

 

[BurnOut]

What all of these folks have said... accuracy actually may be negatively impacted by longer barrels (in regard to barrel whip, which is more more flexible, an 8' long 2x4, or a 4' long 2x4?), but in terms of velocity, there's no replacement for displacement (in this context, read: barrel length).

Velocity brings along with it reduced drop/drift for a given set of conditions, but modern range finders and ballistic calculators can do a LOT to bridge this gap; so ultimately, the remaining thing that velocity brings to the table is energy on target. Given that we're talking about a 375CT here, I don't really think that energy on target is going to be anything to concern yourself with.

If it was me, I'd stick with a ~30" barrel and enjoy the maneuverability inherent to the bullpup platform. FWIW, I run a 30" DTA in 338LM AI and get 3k FPS out of Berger 300s. Running the numbers, that's enough to put ~2600 lb/ft on target at 1000 yards; in other words, in terms of energy, it's essentially the same as a conventional .308 Win at the muzzle. That's enough for me.

Caveat - I have not yet had a chance to shoot that gun to 1000 yards, so I cannot speak to accuracy at that range.

 

[Jackomason]

Like said before, velocity is free. You can use a more conservative load and not be as hard on brass and the throat.

 

[Ledzep]

Just curious, has anyone ever done a thorough test on ES/SD vs. barrel length? I wouldn't think it would be a huge pattern one way or the other, but the thought crossed my mind and I haven't ever seen it tested.

 

[b6graham]

dont some of the KO2M guys run upwards of 40"?

 

[Ripdog28]

dont some of the KO2M guys run upwards of 40"?

Yep, 6-7’ Long gun pushing some serious powder for a .375 pushing a 400g bullet at 3000fps is nuts.

 

[Rudy Gonsior]

Yep, 6-7’ Long gun pushing some serious powder for a .375 pushing a 400g bullet at 3000fps is nuts.

What barrrel length is best is all about the case volume and powder burn rates in relation to bore diameter and projectile weight.

The .375CTs you mentioned are a great example. The .375CT doesn’t really gain anything once you top a 29” barrel. Both me and my partner ran .375CTs for Ko2M, he ran a 36” and I ran a 29”. Both rifles were right in that 3000 fps ball park and if I remember correctly my gun was actually a 40fps faster.

Long story short, we both finished in the top 10, and those 7” extra of barrel didn’t make a difference once you pass that point, other than the fact that my rifle was sub 30lbs and way handier.

Again the sweet spot for every cartridge will be different, .308s seem to top out around the 20-24” on the other hand the 416B for example really seem to shine with a 36”-40” barrels.

 

[8208]

100fps per inch roughly

 

[Sniperwannabee]

i always like the extra length just in case someone charges me, it gives me more distance between me and the enemy to stab him with my bayonet

 

[Rudy Gonsior]

100fps per inch roughly

That’s the kind of misleading information that without any particular reference point makes forums like this a huge waste of time.

 

[THEIS]

Hi,

The below comment is specifically to the 375CT........

Long barrel user beware........it is a pretty known fact that a standard 375CT using the 350gr weight range mono projectiles (Not the super heavies) experiences a weird fouling ring about 3in from the muzzle when running barrels over 29.5". It lightly appears at 30" and gets heavier up to 33". Anything beyond 33" and the fouling ring is same as it is at 33". It goes completely away at 29.5".

Sincerely,
Theis

 

[arghloba]

Hi,

The below comment is specifically to the 375CT........

Long barrel user beware........it is a pretty known fact that a standard 375CT using the 350gr weight range mono projectiles (Not the super heavies) experiences a weird fouling ring about 3in from the muzzle when running barrels over 29.5". It lightly appears at 30" and gets heavier up to 33". Anything beyond 33" and the fouling ring is same as it is at 33". It goes completely away at 29.5".

Sincerely,
Theis

Sounds like some great information to have. Has anyone shot out a 375CT barrel to get a rough estimate on barrel life? 1000 rounds maybe?

Thanks,

 

[Rudy Gonsior]

Sounds like some great information to have. Has anyone shot out a 375CT barrel to get a rough estimate on barrel life? 1000 rounds maybe?

Thanks,

800-1000, 1200 maybe if you go easy but what’s the point in that? ? I’ve haven’t actually shot one to death yet maybe someone else can chime in.

The JJ Rock Co. Rifle I ran at Ko2M, with no sign of give up at around 600ish...so I’d say a .375CT is at least good for 600 rounds, Lol!

 

[arghloba]

800-1000, 1200 maybe if you go easy but what’s the point in that? ? I’ve haven’t actually shot one to death yet maybe someone else can chime in.

The JJ Rock Co. Rifle I ran at Ko2M, with no sign of give up at around 600ish...so I’d say a .375CT is at least good for 600 rounds, Lol!View attachment 6970260View attachment 6970261

You got that kind of group at two miles? You’re a monster!

??

 

[THEIS]

Sounds like some great information to have. Has anyone shot out a 375CT barrel to get a rough estimate on barrel life? 1000 rounds maybe?

Thanks,

Hi,

The drawback to that question is that there are so many variables that the big cartridges seem to have exaggerated outcomes in comparison to the smaller cartridges.

The 375 and such seem to be way way more dependent on not only how fast/slow they are pushed but the actual projectile being pushed, along with what powder is being used to push them...paired with rifling profile being used

Changing any of those changes barrel life...sometimes quiet substantially.

I personally have never went over 1400 rounds with a barrel (That was with standard 350gr class projectile at MV3025). At around that round count the horizontal deviations outgrow the vertical deviations and that is where I draw the line per say....
Nowadays...I change at 1000 rounds and call it good.

I will dig up all the computer data from the RUAG facility in Thun that we tracked groups from on this barrel over the span of first round to 1k round.

Sincerely,
Theis