Saigafreake is right, you did violate a law.
No worries--it's a stupid law and no one here will tell on you.
Just a note: to use magazines of over 10 rounds, you need
ten or fewer foreign-made parts on the gun, off a specific list. This means, on a Saiga, you would need to
replace 4 parts--adding US made parts for ones the gun didn't come with (a pistol grip or muzzle brake) doesn't lower the foreign parts count.
The most common are trigger parts (two will fit from the kit without modifying it the way it is) and the gas piston, and you can find a stock/grip combo that works without modifying the trigger further.
Otherwise, if you convert it to the proper 'AK look', swap out the trigger parts (3), stock, and add a US pistol grip, and you're good.
The magazine counts as 3 parts--mag, floorplate, and follower. Swap the gas piston and use US magazines, and you're good, no other mods needed.
And remember that, unless your Saiga came with the weld-lump 'feed guide', surplus AK mags
will not work. The Saiga magazines use the lip of the mag in front of the bullets as a guide, whereas AK mags don't--you'll have to make sure yours has the welded guide or add a guide to it.
