Hello,

Sorry if this is a noob question, but wanted to pick up some 12 rd mags for my HK USP Tactical .45 full size.  Believe the USP and Mark 23 mags will also fit my gun but wanted to know what was the difference and is there any reason to buy one over the other for a USP Tactical full size.

Thanks,

R1300ZX

MK 23 MAGS FIT ONLY THE 23!

Unless a USP has some sort of a mag well (as the 9mm offers), all other .45 USP mags interchange with the exception of the USP Compact. It holds only 8rds anyway.

There's several threads in here about mag interchangeability. Might wanna search them up.    

+1.

USPf .45 and Tactical .45 mags will interchange, but not with the MK23.

im pretty sure they are the same mag body with a different floor plate.

I thought that the MK23 mag works in the USP 45 but the USP 45 mag will not work in the MK23. The mag bodies are the same but a slight difference is in the base plate.

MK23 MAGS WILL FIT THE USP .45 JUST FINE

The floorplate does not match up exactly but its not even enough to worry about IMO.

That is correct, the Mark 23 mags work perfectly in the USP .45 but the floor plate leaves a gap.  Change the floor plate and you cannot tell the difference.
Now, will the USP mags fit the Mark 23.  No, yes, and no.
No they will not fit because the USP floor plate will not let them lock in.  But what if you change the floor plate to a Mark 23 floor plate?   Still no, and yes.
The older USP .45 mags had short feed lips and regardless of the floor plate change, they caused feeding problems in the Mark 23.  However, most USP .45 mags seen new in the last year or so now have long feed lips just like the Mark 23 has, so if you have USP .45 mags with the longer feed lips, then a change of the floor plate WILL allow them to be used in the Mark 23.  I guess HK figured it was pretty stupid to be making two mags instead of one.


Here is a Mark 23 mag in the USP Tactical:  


Here is the same mag with the USP floor plate added to it:



When it comes to which mag to use in the USP, it matters not a whit.  The Mark 23 mag with the longer feed lips is not one bit more reliable than the short lipped USP mags, so I imagine the reason HK went to long lips on the USP mags is to eliminate making two mag bodies when one would work just as well with both the USP and the Mark 23 with only a floor plate change.