So I am having a bit of a debate with myself..can't  purchase that LW Daniel defense barrel Brownells has on sale, but there is a LGS that has heavy barrels for days, but .750 under the gas block.  Any advantages of taking a heavy barrel and having ADCO contour it to .625 from the muzzle to under the gas block, and keeping it thick (and subsequently heavier :-( ) under the handguards? This is for my XM177E2 build that will probably take longer than my A1 build did.  I figured I would toss the question up on the forum just to see what kind of knowledge is out there..thanks for any responses.

Why not just get a bcm?

I did my E2 with one of these because I couldn't find a lw colt barrel and very happy with it

why not the DD barrel op?

Well you see, what had happened was...   I'm married, I have to budget my hobbies...shameful I know.  So I may miss the sale on DD pencil barrels, just considering the local option of a heavy barrel, and having it machined down to .625 in case I have to go that route for cost reasons...I've got time to do this as I am waiting patiently for more moderators from Brick.  What BCM barrel are you referring to btw?

The advantage would be that from the shoulder behind gas block to barrel extension would still be HBAR profiled, handling heat from firing much better. The thing that would worry me is the fact that the whole rest of the barrel from gas block forward will have a different heating/cooling temperature/rate than the .750 portion. Which could cause a loss in accuracy due to uneven heating/cooling

To be honest, DD never made a pencil contour, it's lightweight.  So it's wrong anyway.  What's the difference?  Lightweight is a .625 over the whole barrel, pencil is about .550 and it does make a difference.  .625 in front of the gas block still looks looks wrong to me.  

It actually steps down slightly in front of the gas block portion. I'll mic it later but it looks like my 20" pencil barrels

The DD barrel I have is .625 under the front sight A frame, and .570 in front of the front sight.
And just for general information, a Colt 723 barrel measures .625 and .575.

I don't see how that will save money.

Prototype heavy barrel XM, third from top.



In the long run you will have spent more to recontour a heavy profile barrel.  http://www.brownells.com/rifle-parts/barrel-parts/rifle-barrels/16-lightweight-carbine-5-56-barrel-1-7-twist-sku100009472-41976-103017.aspx?aid=27795&source=ir&cm_mmc=affiliate-_-Itwine-_-IR-_-59979



Some of us have purchased barrels from J&T/Double Star either directly or through Brownell's these are available on a regular basis

http://jtdistributing.net/store/product1231.html

http://www.brownells.com/rifle-parts/barrel-parts/rifle-barrels/ar-15-m16-5-56-carbine-barrels-prod23131.aspx?avs|Manufacturer_1=DOUBLE%20STAR