I realize the BHO “nub” is different, but is that it?  Will a standard trigger pack work in a NATO stock, just without last round BHO?  I’m sitting here with a NATO stock, no NATO trigger pack, a perfectly good A3 stock setup and the wait for Steyr to get it together is killing me.  I don’t want to damage anything by mismatching parts, but I can live without BHO. Is there more to it, or can I go for it?

I don't recall if the A3 external bolt release nub will interfere with the wall of the NATO stock. I don't think so, but you'll find out in about 2 seconds if it does (the stock pin won't fit if it interferes).

Call Pete and see if he has a NATO BHO, swap 'em yourself.

I believe Maleante is correct and the standard pack fits the NATO stock, but I can only remember going the other way (NATO pack to standard stock).

I was told years ago - no.
NATO to NATO.
But I did not stay in a Holiday Inn lately.

The lower stud below the BHO that interfaces with the A3 stock bolt release lever hits the shelf in the NATO stock, preventing the trigger pack from being fully inserted.  It looks like that stud can be removed, since it freely spins about its long axis.  I need to find an exploded view of the trigger pack...

In the meantime, I have an email into Pete inquiring about NATO trigger pack/BHO availability.  Thanks to all who responded!

Ah bummer, if memory serves, you have to push the flush pin in towards the pack body to remove it, then slide the BHO out and I *think* the A3-specific stud pushes out to the rear of the now-removed BHO.  Vague memory based on WECSOG-converting an A2 pack to an A3 BHO... if you can find a non-NATO A2 pack that might also work (still w/o the NATO BHO of course).  Just removing the BHO entirely might be your best bet for now.

FWIW, a NATO BHO in an AUG magazine configuration causes the bolt to lock open every other round... I never tried the reverse.

Now you've really got me wondering where my collection of spare hammer packs got to