Help me decide

[Jspy]

I've been looking at some of the AR offerings for a while now and was leaning towards the Colt 6920 based on various threads, forums, etc. I have however came across a couple of the 6720's which have me thinking. I would like to have some other opinions on the matter. To my knowledge the only difference are the barrels, but are there other things to consider besides weight,etc. I'm generally not the type to see how fast I can pull the trigger, but should I worry about the smaller barrel heating up more quickly?

 

[mastiffhound]

25 years ago, maybe I would worry. Now, not so much. I read an article around 2008 about two AR's, a heavy barrel and a pencil barrel. I wish I could find it now because it had some info for handloads too. The author tested both AR's and when shot at a pace like a bolt gun they both performed the same. It wasn't untill the pace picked up considerably that the heavier barrel made a difference and it even eventually started stringing. The one thing that made me think of this was that the pencil barrel cooled down more quickly than the heavy barrel and was able to return to previous accuracy quicker. Barrel steel has advanced quite a bit since the 80's. Either Colt will make you happy, Colt is a wonderful choice either way.

 

[Okiegunner]

I am far from an expert on this topic. However in making my AR purchase, this topic also came to my mind.

From what I came to understand:

The heavy barrel should take longer to heat up and begin to deform. It should also take longer to cool down and revert back to original form.

A lighter barrel should heat up faster and begin to flex and deform earlier. It will also cool down and revert to original form faster.

I am not a gunsmith (just an old soldier) so I could be mistaken. However, I have read this before and it seems to make sense to me. For myself, I chose the HB.

 

[MistWolf]

A lighter barrel heats up to temperature with less heat than a heavier barrel and so has less heat to dissipate when it reaches the same temperature. In other words, it takes fewer rounds to get a light barrel hot.

A heavier barrel takes longer to cool off because it takes more heat to reach the same temperatures as a light barrel. But it's quicker to cool than a light barrel because it has a larger surface to dissipate heat. In other words, a heavier barrel will be at a lower temperature than a lighter barrel when both shoot the same number of rounds and will dissipate heat faster.

The light barrel will serve you fine and makes for a livelier handling rifle

 

[Ian]

I'd go with the light barrel, because I think it's more likely that you'll appreciate the handier-carrying rifle than the one that can give you more sustained fire.