Can an M1A be built w/ a bull barrel, I assume it can't since all the barrel band and gas ferrel band are certain spec diameter, it's not possible ?

I don't know, but I'm sure I wouldn't want to lift it

H20,
I was playing w/ my EBR Scout (14lbs +), and how I love this thing, I kinda want to build a 24" bull barrel EBR for long distance, kind of like the DPMS LR308 bull, I bet if it was possible, this baby would be close to 18lbs

There were three in the 1970s.  From the 06/03/07 version of the Online Edition of M14 Rifle History and Development at www.imageseek.com/m1a:

"M14 Product Improved Rifle

Beginning in 1970, the U. S. Army Materiel Command funded a project at the General Thomas J Rodman Laboratory, Rock Island Arsenal to further improve the M14 rifle.  A civilian employee, Robert E. Snodgrass, headed the project.  As an aside, Mr. Snodgrass developed a side two point scope mount for the M14.

Three prototype rifles for the project were produced.  Each rifle weighed approximately 10 ½ pounds with sling and empty magazine.  These 43 " long rifles had 24 " heavyweight stainless steel barrels, two bedding lugs, improved gas systems, laminated walnut stocks, no hand guard, hooded target grade front sight, and no select fire components including removal of the selector lug.  The bedding lugs on the first prototype model were located at the front and rear ends of the receiver.  The bedding lugs for the second and third prototype rifles were placed at the front of the receiver lug and the operating rod guide.  The barrel on the first prototype rifle was broach cut (see The Barrel Making Process).  Remaining barrels for the M14 Product Improved Rifle project were to be made by the hammer forging method.  These rifles grouped less than two minutes of angle at 100 yards with M118 ammunition.  This was about a 100 % improvement over the acceptance standard of the M14 NM rifle specifications in 1975.  By 1975 the funding for this project was stopped."

Different,
Thank you for the link & history, I guess the only choice for a long range bull 308 semi available is a DPMS LR308 or similar variants. I have read their reliability is a hit or miss

Quoted: ...These rifles grouped less than two minutes of angle at 100 yards with M118 ammunition.  This was about a 100 % improvement over the acceptance standard of the M14 NM rifle specifications in 1975...

Just for comparison purposes:
My medium heavy 18.0" Crazy Horse barrel has grouped less than 1 MOA @ 100 yards with M118LR ammunition.

AR15KittyKat, you may want to consider the 22.0" Crazy Horse instead of a Bull.

Here's what the heavy barrel looks like.  It's huge right up to the gas system and two pounds heavier than a standard GI tube.