I got to examine a friend's 2003 WASR-10 that had been factory converted to hi cap mags last Friday. The sides of the mag well and the two single stack mag spacers spot welded to the inside of the of the receiver on each side you could see the bare metal where they were ground down. There were plenty of metal shavings inside the receiver.
They had got a little over zealous grinding and a hi cap mag had plenty of side to side play. You had to be careful when inserting a mag as the mag well opening was so large and the spacers didn't even touch the mag. Neither guided the mag into the mag well. You had to make sure the rear of the mag was in the dead center of the mag well or it wouldn't lock in. We had quite a hard time changing mags till we set the rifle down on the bench and figured out what was going on.
Converting a singel stack mag WASR-10 to use high capasity magazines(LCMM) would violate this Treasury ruling.
http://www.atf.gov/firearms/assault/treasrelease.htm
After the implement date of the above converting(assembling) a AK rifle that uses hi cap mags, the BATF ruled that a thumbhole stock was the same as a pistol grip. The rifle would be in violation of section 922r and become a illegal assualt rifle.
http://www-2.cs.cmu.edu/afs/cs/user/wbardwel/public/nfalist/atf_letter32.txt
So the converted rifle could only have 10 imported parts otherwise you would be commiting a federal crime.
From United States Code Title 18,Chapter 44,Section 922.
(r)
It shall be unlawful for any person to assemble from imported parts any semiautomatic rifle or any shotgun which is identical to any rifle or shotgun prohibited from importation under section 925(d)(3) of this chapter as not being particularly suitable for or readily adaptable to sporting purposes except that this subsection shall not apply to -
(1)
the assembly of any such rifle or shotgun for sale or distribution by a licensed manufacturer to the United States or any department or agency thereof or to any State or any department, agency, or political subdivision thereof; or
(2)
the assembly of any such rifle or shotgun for the purposes of testing or experimentation authorized by the Secretary.