I know I should know this, but can you strip the threaded FSB and 90 degree gas block off of the barrel of a Bulgarian stamped AK-74 kit and use them to replace the originals on a Romanian SAR-2?

Are the barrels different diameters or something?

Thanks,

Thekatar

The Bulgarian and Romanian 74s are different diameters,the Bulgarian bbl is slightly bigger.

If you can swallow the labor cost, just buy a new bulgarian front end.  Thats what I did.  You get the correct gas block, lugs, comp, and threaded FSB all in one shot.  I did that when I sent my SAR2 in for upgrade.  It has a AK100 folding stock now too.  Except for the words SAR on it, I dont' think it has any romanian parts left.  (RSA trigger group)  I'll throw this pic up again, its the only one I have.  

This is the SAR2 upgrade kit.  Ditch those crappy romanian parts.  
www.k-var.com/product.asp?0=211&1=212&3=628

5.45x39 Caliber

BULGARIAN BARREL:  O. D. DIMENSIONS  
Chamber .871"  (22mm w/ .004 - .005" press fit)
Rear Sight Base .694" (17.5mm w/ .003 - .004" press fit)
Handguard Retainer .671"  
Gas Block .594" (15mm w/ .003 - .004" press fit)
Front Sight Base .575" (14.5mm w/ .003 - .004" press fit)
GERMAN BARREL:
Chamber .867"  (22mm w/ .001 - .002" press fit)
Rear Sight Base .694" (17.5mm w/ .003 - .004" press fit)
Handguard Retainer .671"  
Gas Block .594" (15mm w/ .003 - .004" press fit)
Front Sight Base .575" (14.5mm w/ .003 - .004" press fit)
ROMANIAN BARREL:
Chamber .908" (23mm w/ .003 - .004" press fit)
Rear Sight Base .694"  (17.5mm w/ .003 - .004" press fit)
Handguard Retainer .671"  
Gas Block .594"  (15mm w/ .003 - .004" press fit)
Front Sight Base .517" (13mm w/ .004 - .005" press fit)
ROMANIAN SHORT BARREL:
Chamber .908" (23mm w/ .003 - .004" press fit)
Rear Sight Base .694" (17.5mm w/ .003 - .004" press fit)
Handguard Retainer .671"  
Combination Gas Block & Front Sight Base .575" (14.5mm w/ .003 - .004" press fit)


Taken from AA-OK.com