I advocate gas piston rifles but this is more than a theory. ALL ELSE BEING EQUAL....a moving piston as a bullet is rolling through a barrel does can cause some inconsistent vibrations (harmonics) with the piston which can affect accuracy. Much of that can be mitigated with either a thicker...
Use any IWB holster with a neoprene fisherman's wading belt. No heat build up, repels sweat and doesn't require you to buy another holster!
I tend to wear sweats around the house too, so I bought a neoprene fisherman's wading belt (Simms is the brand; see link) and I attach the IWB holster to...