I'm considering buying this lightweight 6.5 Grendel barrel and would like to use it with my specwar762.  Is there any issue with attaching such a heavy object to the end of such a thin-contoured barrel?

http://www.undergroundtactical.com/products/6-5-grendel-barrel-ultralight-w-bolt.html

This may be not be a direct answer, but BCM said that their enhanced lightweight fluted barrels (ELW-F) were not meant for suppressor use due to possible contortion from the weight of the suppressor. Not a quote but it is more or less the gist of what they said. I would imagine the same would be for the barrel you posted.

I use my SDN-6 on my 11.5" LW profiled BCM upper all the time. Hasn't had any bad effects except moving my POI about 6" low at 100yds lol

I ran POI testing across my commercial and Form1 5.56 and 308 cans that ranged from 8oz to 23oz on a rigid 12.5" Compass Lake barrel and then on a 11.5" LW DD and 16" BS Hanson (a hybrid profile that is sighly heavier than a LW).  There was no notable difference.

Many LW profiles on an AR are Gov't. Profile behind the FSB so for a 14.5" or 16" barrel you only have a few inches of "light" barrel, really.  My K-31 with a 28oz can shifts POI significantly downwards when suppressed and that is a similar profile to some of the modern tapers, and it is long (23.5" IIRC).  My ARs don't shift downwards with light barrels, but I'm sure they would with that can and a pencil barrel.

I have since prioritized size and light weight for my cans over absolute attenuation so that will be my last heavy can on a light barrel.

I am okay with POI shift as long as it is consistent. I was more concerned about any other adverse affects.  I'll try contacting the barrel maker.