What BUIS, if any, are on your SIG MPX, MPX K, MPX Black Copperhead K, Copperhead that work with a PCC? If you used rifle sights did you have to file down the front post? Thanks.

I put a set of Bobro Lowriders on my 8" MPX. Not the most solidly locking irons when in use, but they're good enough for a pistol caliber. However I wouldn't rely them with any rifle caliber shooting out at distance...if I had eyes that were good enough with open sights to be shooting out at distance. In hindsight they weren't worth their cost but at least they "look cool". And no, I didn't have to mod the front post. There's enough adjustability to sight out to 70 to 75 meters, which is what I think I had set up my MPX for (it's been minute).

I picked up a set of BUIS that Sig made specifically for the MPX. I don't think they make them anymore but you can find them in the secondary market. You should put a WTB ad in the classifieds.