Barrel Choice for Standard Ammo

[sentinel77]

Hi, I'm trying to decide on which barrel to use for standard military ammo such as 55gr M193 and 62gr M855. I've been told recently that the Sionics 1:8 16" BB barrel is a solid choice as the 1:8 twist rate can theoretically stabilize 55gr and 62gr ammo better than its 1:7 twist counterpart. However, tipping the scales at 29 ounces, it's not exactly a light barrel. The meaty profile may better help with heat dissipation but only at the cost of maneuverability. Other well known and highly touted options are the Daniel Defense CHF lightweight barrel (24 ounces) and the Centurion CHF lightweight barrel (26.9 ounces). Though these barrels fully twist every 7 inches, the reports are that they shoot the lighter grain stuff every bit as accurately as the 1:8 and 1:9's. The only drawback to choosing either of these CHF barrels is the price (Sionics 16" retails $190; DD 16" retails $289; Centurion 16" retails $325).

With all the barrel configurations and flavors out there, from CHF vs BB to 1:7 vs 1:8, which barrel is the best value pick for combat applications (running and gunning) when mostly using standard military ammo (M193 & M855), and occasionally your 69gr or 77gr SMK's?

[MorphCross]

Not entirely sure if you missed it but Sionics has a barrel that weighs 22 ounces. I don't think you will notice enough of a difference between any of those three in terms of precision if your goal is for shooting while moving. I may have misread your intent but things like an accelerated heart rate that goes along with running will end up playing havoc as much as utilizing M855 and M193 as the primary ammunition.

[Eurodriver]

Not entirely sure if you missed it but Sionics has a barrel that weighs 22 ounces. I don't think you will notice enough of a difference between any of those three in terms of precision if your goal is for shooting while moving. I may have misread your intent but things like an accelerated heart rate that goes along with running will end up playing havoc as much as utilizing M855 and M193 as the primary ammunition.

I believe that one should seek the most mechanical precision and accuracy out of their firearm regardless if the purpose of that firearm might be inherently inaccurate.

FYI, OP, a heavier barrel does the exact opposite of helping with heat dissipation. It actually takes longer for heat to dissipate. The advantage is that, all things being equal, a heavier barrel will heat up more slowly. For your purposes this is a moot point.

[sentinel77]

Not entirely sure if you missed it but Sionics has a barrel that weighs 22 ounces. I don't think you will notice enough of a difference between any of those three in terms of precision if your goal is for shooting while moving. I may have misread your intent but things like an accelerated heart rate that goes along with running will end up playing havoc as much as utilizing M855 and M193 as the primary ammunition.

Yea I saw a few videos of their patrol rifle that has the lightweight barrel. My only concern is that it'll heat up quickly and POI shift will be pretty bad. I've seen videos and read reviews of the DD 16" lw barrel and that thing will not experience any POI shift even after 3-4 mag dumps. I'm willing to bet the Centurion has the same rigidity due to the hammer forging and rigid steel (heard FN uses a stronger steel for their HF barrels). But, you're right. Even with a more durable barrel, running and gunning will probably negatively affect accuracy far more than anything else. As the guy above mentioned, I'd like to have the best option (accuracy and durability wise) for the peace of mind, knowing that my barrel can handle any and all situations thrown at it.

[Hammer_Man]

I don't think you will notice much of a difference between 1:7 and 1:8 twist barrels, given the ammo you have decided to use. What will make the biggest difference is your level of skill/ability as a shooter. Of your listed choices I would go for an FN CHF barrel, (or Centurion) as I have had good experiences with those barrels. I have not used any Sionics barrels personally, but I have heard good things about them from other forum members.

[MistWolf]

...a heavier barrel does the exact opposite of helping with heat dissipation. It actually takes longer for heat to dissipate...

This is not so. A barrel made with a greater mass of the same material with the same surface area will radiate heat at about the same rate as barrel with less mass. Therefore, if a shooter were to dump 20 rounds through a barrel with greater mass and another were to dump 20 rounds through a barrel with less mass, both would dissipate heat at about the same rate and reach room temperature about the same time. But the barrel with less mass would reach a higher temperature after the 20 round mag dump because the heat more concentrated.

If the same shooters were to shoot both barrels until the reached the same temperature, say, 250 degrees F, it would take more rounds to heat the barrel with greater mass to reach that temperature than the barrel with lesser mass. Then yes, it would the heavier barrel longer to reach room temperature than the lighter barrel because it has more heat to dissipate.

It's like filling an air compressor tank to 250 PSI. If two air compressor tanks, one with a 5 gallon capacity and the other with a 10 gallon capacity, were filled with the same amount of air, the smaller tank would be charged to a higher pressure. If outlets of the same length and diameter were used to drain each, it would take about the same time for each tank to empty.

However, if both tanks were charged to 250 PSI, it would take a greater amount of air to charge the 10 gallon tank and would thus take longer to drain.

Generally, barrels with a heavier profile have a larger surface area. A larger surface area means the barrel can dissipate more heat in the same amount of time. Therefore, the heavier barrel with its greater surface area can dissipate the heat from a 20 round mag dump quicker than a barrel of lesser mass and do so at lower temperatures. (This assumes both barrels are properly designed with the needed mass at the chamber end where it's most effective at handling heat.)

[vicious_cb]

Mist is correct, heavier barrels have both greater heat capacity(ability to absorb heat) and greater ability to dissipate heat.

As for the OP, stop worrying about 1:7 vs 1:8, buy the best barrel you can afford in the profile you want. Why? Because your limiting factor in accuracy will be the shit accuracy of the M193 and M855 "standard ammo" you'll be shooting. Having a better barrel doesnt make inaccurate ammo into accurate ammo.

[_Stormin_]

What distances are we even talking about here? You're not going to be shooting 100 yards plus while moving are you? As was just said above, your ammo choice will be far more limiting a factor than barrel weight and twist rate from any of the aforementioned options.

[MWAG19919]

FWIW my BCM CHF 1:7 ELW and my dad's DD 1:7 lightweight barrels shoot 55 gr handloads about 1.5-2 MOA. The barrels shoot 62/64 grain stuff even better, and we really haven't shot enough heavy stuff to make a judgement. I've only ever shot 1:7 AR barrels, but I hear 1:8 is just fine as well.

Bottom line, any of the barrels you're considering will be fine. Cheap ammo + movement will produce poor accuracy in any barrel, and the barrels discussed should all perform well with match ammo should you choose to run that someday. I say "should" because every barrel is an individual.

[BigTex2000]

I have no expertise, but if two barrels are made of the same material (and assuming we are talking about the same length) then the greater mass barrel will have more surface area than the less mass barre, since it will be thicker. So, one of your assumptions seems to be incorrectly made. That said, I do not purport to know if this difference in surface area would be significant to heat dissapation.