I have the required parts, what I need is a template, jig or schematic that explains where to drill and tap the 870. Does anyone have one or know where to find it other than spamming KAC?

bump for answers

ETA-

For my own clarification a masterkey is a SBS and not an AOW because it is attached to a buttstock via the host firearm?

I'm also pending a SxS shotgun build that appears would be an AOW with a pistol grip and short barrel only, but I could register it as an SBS and still have the ability to attach a full stock and not only a pistol grip? but would list a OAL with a stock attached even though it would primarily be used with a pistol grip?

If the gun you are using for your project started life with a stock, then it can never be a AOW.  It would be a gun made from a shotgun, thus, a SBS.

A Form 1 build costs the same 200 dollars whether you make a SBS or an AOW, so you are right, making an SBS gives you more flexibly in changing configurations after the initial build.

The Form 1 description, is of the gun you are going to make the day you get your form back - approved.  Those are the barrel length and OAL you use.  Once the initial build is made, you are then free to make any changes you want.  Martinsburg asked that you notify them of any permanent changes.

The only real benefit to making an AOW v SBS, is that an AOW does not require a 5320.20 approval for interstate travel. But, again, if the original gun has a stock, it can never be a AOW.

Thats clear enough, that and the Efile system doesn't even give AOW as an option. Submitted two SBS F1s yesterday.

I've submitted 3 AOW E-Form 1's in last year so the option is there.