Came across this link which might be of help to others who haven't seen it.
I don't use moderators through choice, and have no idea who this RFD is. He might be a member on here for all I know, but it's a useful and informative piece.
There is another point worth mentioning about the care of moderated rifles. Those which are fired in quick succession are more at risk of heat erosion because of the lagging effect of the sleeve. This erosion is where the barrel steel is literally washed out by flame temperatures which are (momentarily) much higher than the melting point of steel. OK this applies to all rifles, but bare barrels cool down much quicker than 'insulated' ones. I've seen some people fire a box or two within 10-15 minutes during sighting in with new rifles/new mods, sometimes both. When clearing weapons on the firing line you can't touch the barrel or chamber,or you take the skin off your fingers.
What nobody knows as a buyer of any rifle is how it's been treated or cared for. Round 'counts' and age are useful pointers if you trust the seller, but there's no way of identifying a rapidly-fired rifle from any other.... yet moderated rifles actually encourage this practice because they're comparatively quiet and recoil free. Personally I wouldn't buy a secondhand rifle which had been fitted with a moderator, but it's a cop out for me because I don't believe in mods. If I did it would have to be factory-threaded, and brand new. Now you can all have your say ....