HK 94 SBR
I built mine from a SP 89, but it works the same way with an HK 94.
for a semi auto all you need is a stock unit. for the Hk 94 you can use an HK A3 slidding stock or a Flemming side folding stock.
Flemming built the stocks for HK. you can buy them with the HK logo for alittle more or get one with Flemming logo for alittle less. shop around i have seen the Flemming branded stocks for $150 up and the Hk branded for $200 up. once you have your form 1 back just push out the two stock pins slide the stock in the receiver and push the two pins in.
on the Hk 94 you must deceide on if you want to shorten the HK94 barrel or replace it with an MP 5 barrel. The barrels are pressed and pinned in the receiver and you must have the correct fixtures to replace it.
receivers have been ruined by people not equiped to change a HK94 barrel.
my MP 5 KPDW has a Flemming sear and stock, also a factory 3 lug MP5KPDW barrel.
hope this answered your question. any other questions just ask.