it is legal for a owner to replace the t-hole with a pistol grip configuration furniture set as long as the law (usc 18, sections 922(r) and 922(v)) are followed.

simply put, this means that your friend must replace 5 of the legally described firearm  parts that were made in with 5 of those same parts that are made in the usa.

it works like this:

your friend buys a usa made buttstock and pistol grip from k-var...that's 2 usa made parts.

he then buys a fire control group (hammer, trigger and disconnector) from redstararms...that's 3 usa made parts.

adding those 5 parts makes the changeover to a pistol grip configuration/high capacity mag accepting rifle perfectly legal.

the rule is, the rifle (with a grip and the ability to accept high cap magazines) can have NO MORE THAN TEN imported parts from the atf list of 'official parts' (a screw or pin will not count as a 'part'. only major components qualify...and even then, not all of them are on the list).

so...if you add a brake to that pistol grip rifle, another usa part must be added.

yes, echap, your mak-90 may be legally reconfigured into a pistol grip style kalashnikov.

t-stox, the quality of the american fire control groups has come a long way in 5 years.

the redstararms parts are, imo, the best in the biz. gordon's g2 sets are also darn good. although i have never tried them, i would assume the parts that are made by arsenal inc. are also of good quality.

the only set i know of that has trigger slap is the century oem parts that come in the wasr/sar's (although even some commie pre-ban guns exhibit trigger slap).

most folks change out the fire control group because of the relative ease of the swap out.