Originally Posted by
HCM
I can't definitively answer your question but if you read between the lines I think the answer to your question is below:
My Agency, with 15,000 armed LEOs has adopted a "DHS" specific SKU / model P320 carry 9 mm with an X grip as our standard issue pistol, replacing the SIG P229R DAK 40. The testing and adoption process spanned 3 to 4 years and over 200,000 rounds of Gold dot duty ammo.
In addition to GOV issued guns, we are allowed to use certain agency approved Personally Owned Weapons (POW). Unlike the approved Glock POWs and the SIG P365 POWs which may be standard commercial / Blue Label/ IOP guns, only DHS SKU P320s (usually purchased via an agency specific program) are authorized for POW/Duty use.
We are allowed (at least on POW) to use most SIG OEM Grip shells (except is the Legion Tungsten) and most SIG OEM Slide / exchange kits (no porting or lightening cuts in the slide permitted).
The DHS sku FCU has been described to me as an M17/M18 FCU without the thumb safety.
Based on this fact pattern, Commercial slides and grips ok - commercial FCU no go, a reasonable person might infer the issues were in the FCU.