So, I saw a Sig P320 compact at a pawn shop with an OD green frame and night sights, barely used and got it for $340 OTD.

I fired it today, worked great, accurate, but I noticed some differences between it and my 320 TACOPS CA.

First, the guide rod sticks out a bit on this one.  I compared it to my TACOPS, which doesn't do that.  I swapped slides and guide rods around on each and it only sticks out a little on the compact, see pic below.
Attached File


Also, the slide on the compact is different, one large oval hole on the upper side as compared to the TACOPS with two small holes in the same place.  The compact is dated 1/31/15.  TACOPS is dated 8/2/16.

Compact slide:
Attached File


TACOPS slide:
Attached File

I have the full size p320rx and compact rx and guide rod doesn't stick out of either. Something is wrong with that guide rod.

ETA: haven't looked at the slides to see if anything is different between the two.

Guide rod doesn't sound right. I think early models required the guide rod be seated a certain way. Play with the rotation of the rod to see if that helps.

As for the slide lightening, word I got is that SIG was playing with weight to get proper operation with all kinds of loads. Not sure, but newest production may have even eliminated them.

It's the guide rod.  I played around d some more and for some reason it just sticks out on either gun.

I will get another and see what that does.

That is the way the guide rod was made when the P320 compact first came out.  In late 2015 Sig changed over to the flush ones.  I took delivery of 250 P320's at work in Oct 2015.  About half had the recoil assembly you have shown and the rest were the flush ones.  

The lightening groves have changed with production upgrades, we have a few different versions.  I'm just guessing is it quicker to drill out a few holes instead of machining out the larger oval or Sig decided change the total weight of the 9mm slide.  David

My compact made Jan ‘17 has no lightening cuts in the slide and guide rod is flush.  It is a MA safety version but shouldn’t make a difference.