I’m no expert, so this is just my understanding . . .

Proviron binds extremely well to SHBG (sex hormone binding globulin), the hormone responsible for reducing free testosterone circulating in the body. Better than most other AAS, it seems.

This is good because testosterone bound to SHBG is not 'free testosterone'. It's been taken out of circulation and utilized and is therefore not available for muscle building purposes. Proviron added to a test cycle will bind to and saturate the SHBG, effectively preventing the SHBG from stealing this testosterone, which in turn increases the amount of 'free' testosterone available for muscle building, without merely adding more testosterone. There will be a limit to how much testosterone you can add before you saturate your receptors anyway.

Proviron also reduces the ability of estrogen to bind to estrogen receptors, therefore preventing problems caused by estrogen build up, such as gyno and water retention. This beneficial anti estrogen effect seems to have been superseded by the use of anti estrogens such as Aromasin and arimidex etc.

To get back to my point about natural test production . . .

The exogenous use of testosterone or tren or whatever other AAS you use is going to halt your own endogenous natural test production, whether gradually or immediately. I understand that using proviron on its own might not halt natural test production to the same extent, but I don’t see how adding it can do anything to prevent this inevitable cessation caused by using exogenous test or tren from happening. Proviron just doesn’t have the mechanism to do that.

Sorry, mate, I wasn’t trying to make a big issue of it. In a way I was half hoping someone knew a way to keep natural test production going while on AAS that I didn’t know about.