Thanks Malco,
sorry but I haven't thought to look in on this thread for a few days, being otherwise engaged

So, yes, the old guys expected the bullet to 'slug up'. Some of the other posts show better accuracy with larger bullets but I notice the discussion moving on to headspace and excessive web expansion.

Could it be that the bigger bullets, while shooting better and suppressing 'Young gas', might bring higher pressures by having to engrave so much deeper?

On the matter of measuring headspace, is the old method of putting little discs of feeler gauge behind the cartridge until the bolt won't close too obvious to mention?

Daryl, when you mentioned the web starting 3/8" up from the rim, I thought that sounded a long way, but you a right; the 6.5x54 seems to have a longer solid head than any other rimless calibre we have here.

As you know, I reload so intermittently that my grip on the craft is a bit dodgy - but fragments of info from my youth haunt me from time to time. Isn't expansion ahead of the web more an indication of an oversized chamber (except where there's excess headspace and an incipient separation) than the definitive pressure warning? My understanding was that minute expansion (in 10,000s) of the solid head was the real deal - and that even that was expansion after the large movement caused by the initial firing of factory ammo.

Maybe I've been unlucky but the few front-locking rifles we've got all give more expansion of both web and solid head from factory fodder than I'd like - and, yes, I do clean the barrels before shooting. Maybe that's why I don't reload more. A chemical engineer I know who used to work for ICI won't touch reloading with a barge poll for safety reasons, though he has quite a few rifles and used to shoot pistols. He does use his knowledge to make great wine and vodka, however.