A Machinist guide to SKS / AR magazine conversion

[xtriggerman]

  This article is primarily dedicated to what needs to be done to the SKS receivers magazine well so an unmodified AR ASC 7.62x39 (or similar) magazine  will function properly and function the SKS bolt hold open. A complete conversion would need a magazine well device such as the Marcus G9 mag well or similar magazine well device that holds the AR magazine up to the receiver.

Top view of the same first cut

Where to measure for the .180 wall thickness

 Moving forward

 Results should be as pictured


   
  The SKS bolt hold open will need to be modifyed to function properly off the AR BHO follower step. Despite this slight reconfiguring, it will still function in an unaltered SKS using the factory fixed box magazine.





  A very important modification is adding a 5 and 7  O"clock pair of feed ramps onto the chamber face as pictured. This will ensure flawless feeding from good magazines. Just be careful to not go deeper into the chamber wall as you see it here. The ramp cut is only slightly deeper than the factory extractor cut.

  That wraps it up. Hopefully, if the G9 adapter becomes available again, with these particular mods an SKS will have a seemless mag compatability with ARx39 rifles.

[1mlt]

Thank you XT for publishing this. If you don't want/can't do this mod we have vastly improved the install procedure of the G9 to use our modified ASC mags. We will have a working prototype this week for testing. We have redesigned how the G9 locks up with the rifle and how the mag angle-to-receiver is set. The entire rear locking "system" has been scrapped. In place we cut two "slots" that correspond to the the cross pin on the trigger assembly. Remove the factory cross pin and install the new longer pin in its place. Our modified mags will still run in the x39 AR.

Here are the basics of the install procedure. You still need to trim the trigger tangs back and modify the stock. Remove the trigger and stock and set aside. For fitment purposes the stock will not be initially installed. Leave it off so you can clearly see how the system locks up. Position the front locking lug onto the rear sight trunion. Place the G9 over the locking lug and loosely install the screw. (Replace the modified stock.) Lock the trigger group into place. Insert an empty mag w/bolt locked open. Tighten the front screw to lock the adapter in place. Press the mag release and the mag should "pop" out on it's own. This sets the "timing" of the mag to the receiver by allowing the adapter to "slide" to the "sweet spot" and set the optimum angle of the mag-to-receiver. Contact me if you have questions.
Marcus

[xtriggerman]

 Marcus, I'm happy that you have kept moving the G9 adapter forward. The receiver milling is really very basic in operation and any small bench top Mill/Drill type machine can handle it. Either way, since I have experience with your adapter, I can clearly say, its a fine accessory. The new design is a rock solid performer. I personally don't have a business doing this sort of work but as I said, if the guys want to use un cut mags, any shade tree mechanic should be able to bang out the work inside an hours time.
  The best of luck to you with the fine G9 adapter!

[1mlt]

Marcus, I'm happy that you have kept moving the G9 adapter forward. The receiver milling is really very basic in operation and any small bench top Mill/Drill type machine can handle it. Either way, since I have experience with your adapter, I can clearly say, its a fine accessory. The new design is a rock solid performer. I personally don't have a business doing this sort of work but as I said, if the guys want to use un cut mags, any shade tree mechanic should be able to bang out the work inside an hours time.
  The best of luck to you with the fine G9 adapter!

The objection I run into is the SKS owners don't want to make permanent modifications to their rifles. Most are running T6 stocks or "others". Some get a M or D stock to use. The G9 works super well with bulpup type stocks also. I have two of "frogy's". Those work w/o any mods and your numbs match stock remains unaltered. Trimming the two tangs on the trigger assembly won't hurt returning the rifle to "spec". Plus, we can cut the mags for the customer so all are the same.