AR buttstock question

[blank4u47]

Sorry if this has been posted before I couldnt find it. I have a fixed A1 buttstock on my new ar build for some reason I had to piece it together but my question is do I need a castle nut for it or a spacer? I also wanted to know if I need to fill the the butstock with a rear spacer wedge? Sorry for the newbi questions but this is my first fixed stock build

[kendog4570]

The A-1 should fit over the buffer tube and attach with the upper butt plate screw. The A-2, being 5/8" longer, takes the same buffer tube, a spacer, and a longer screw. Both of them trap the rear take down pin detent and spring. No castle nut on either. Hope that answers your question.
Ken

[blank4u47]

Thanks for the response that sounds exactly what I needed to know