I have the Compact RX slide and it shoots my 4.7” threaded barrel on the same spring without issue, at least with medium and up loads (1050fps at 115gr).
That barrel 4.3” in your post may be too short for your non “X” compact slide. Note the X-compact slide is for a 3.6” barrel, the "non-X" Compact RX that you (and I) have is for a 3.9”. The thread protector on mine is ~0.45”, so I wonder if it or a muzzle device would hit the slide and not fully engage the threads? I would verify with Sig before purchase.