OK...here goes:
1" spacer is to increase LOP. There is a 1" spacer that fits between the buttstock and the lower and there is an internal spacer that fits on the back of the recoil buffer. These items, along with a couple of screws, come with in the DPMS spacer package.
The RRA stock came with stock, recoil spring, shorter buffer, and short buffer tube.
Everything from both of these packages was used with the exception of one screw which is a long one and is intended for use with an A2 stock if you use the spacer to make the LOP even longer.
SO...
Tweak, there are BOTH internal and external spacers. The extra long screw is for use with the A2 stock. The long screw is being used. The rear of the buffer is clean and has not impacted the screw. The bolt comes all the way to the rear, as far as I can tell. There are no problems with the bolt locking back on the last round or short-stroking.