Also the prs enhanced butt pad will lengthen it a little too if needed.

for the record yes it looks like you can fit a sling mount where i wanted to 

 

 

http://firespeedtactical.com/review-magpuls-moe-fixed-carbine-stock/

Yes there are 2 plastic spacers. One is for a sling and one is for no sling.

Ill switch spacers today and take a pic

for the record yes it looks like you can fit a sling mount where i wanted to 

 

 

http://firespeedtactical.com/review-magpuls-moe-fixed-carbine-stock/

The sling mount you asked about will not fit with the Magpul fixed carbine stock.  The mount attaches behind the castle nut and as you can see in your posted reference pictures. The Magpul bushing for sling attachment butts up against the castle nut removing the needed space to attach the mount you referenced.  Are there other mounts that work, yes.  Magpul ASAP is one.  It is not a quick release type, and requires you to replace the plate in front of the castle nut.  

The sling mount you asked about will not fit with the Magpul fixed carbine stock.  The mount attaches behind the castle nut and as you can see in your posted reference pictures. The Magpul bushing for sling attachment butts up against the castle nut removing the needed space to attach the mount you referenced.  Are there other mounts that work, yes.  Magpul ASAP is one.  It is not a quick release type, and requires you to replace the plate in front of the castle nut.  

 

Thought i was screwed on all mounts my bad.

 

 

Would this work? https://www.primaryarms.com/Troy-OEM-M4-Sling-Mount-FDE-p/smou-m4s-00ft-00.htm 

No, it will not. As seen in the above picture of Shawn's AR, the front bushing of the stock seats against the castle nut. An optional bushing is enclosed with the stock, that has a bottom taper allowing room for a plate with a sling attachment but again, the bushing seats against the castle nut.

I don't have any time with one, but it looks like you could run something like this:

 

http://store.troyind.com/OEM_M4_Battlesling_Mount_p/smou-m4s-00bt-00.htm

 

As it only replaces the plate behind the castle nut, not the nut itself and won't interfere with the stock itself.

 

ETA: its the same Troy OEM sling adapter you linked to above on the Primary Arms site.

Thought i was screwed on all mounts my bad.

 

 

Would this work? https://www.primaryarms.com/Troy-OEM-M4-Sling-Mount-FDE-p/smou-m4s-00ft-00.htm 

It should, however it may require trimming of the bushing on the stock near the barrel nut.  All I can say is give it a try. 

It should, however it may require trimming of the bushing on the stock near the barrel nut.  All I can say is give it a try. 

 

Already ordered the stock should be here in a few days i'll put it on and see if i can find some dimensions for the troy one.