Is there any good reason not to go with a 6720? The 6920 is the standard that is regularly recommended. Why not go lightweight when the option exists? I think the 6720 plus a FSP 12" rail would be pretty handy.
(I’m not necessarily asking about standard vs. LW profiles, as much as differences between these models specifically.)
Thanks (& Merry Christmas!)
Nothing wrong with the 6720. The difference in barrel profile should not be a relevant issue, unless you plan on dumping mags after mags in a very short period of time.
…and even at that, the 6920 is not going to a much better job of this. As has been beaten to death, the standard M4 barrel profile isn’t thicker where it would actually count for this.
Here’s your difference:
The 6920 looks cool.
The 6720 -is- cool.
Any additional thickness to the barrel helps to keep temps down and prevent barrel warping at higher temps. It’s a giant heat sink that spreads the heat out.
I don’t plan on mag dumping but if I was in a large shootout, I would appreciate the thicker barrel.
I have one of each and prefer the 6720. I like the reduced weight and better (to me) handling characteristics.
Mine is pretty plain with the original Matech, an H1 and sling as I don’t want any more weight or clutter on it than necessary. Trying to keep it simple and basic.
I had a lengthier reply crafted, but it all came down to this:
No.
Why not go lightweight when the option exists?
Do that.
Thanks (& Merry Christmas!)
You too.
I hate LW profile barrels. But maybe I’m compensating for something… 
The extra mass of the M4 profile is ahead of the gas block. The heat from firing is concentrated in the chamber area which is under the handguards. While the extra mass ahead of the gas block helps some, it’s location keeps it from heatsinking the chamber area to reduce throat erosion. Moving the mass from ahead of the gas block to the chamber area would increase the capability to handle the heat while lightening the rifle at the muzzle to improve handling without adding weight.
MarkM, you say you hate LW barrels, but compared to what? The gov profile? M4 profile? HBar profile? Of the three profiles, only the HBar really handles heat better
Isn’t the Noveske a 4th option? Also recently seen on the Spikes “Optimum” profile. M4 weight with a smoothed contour throughout - this is a little better handling, and may be a tad better on heat than the M4.
There are many profiles but not many that show any objective improvements. A Spider barrel over a Pony? Really? As far as profiles I’m pretty enamored by the Centurion LW’s. Other than for a precision type rig I very much prefer LW profiles.
Yeah - probably move that Noveske N4 to the first option and just bypass the standard military issue stuff and get something of higher quality.
Not saying that my Colt’s are not high quality or anything - but Noveske Rifles are in a much different league.
Godzilla vs. Rodan. Godzilla vs. Mothra. Godzilla vs. Giant Robot. Take your pick.