Why not ditch crown seals altogether? To repeat an old post...
I have a supply of coopers bottles and screw top lids and all I do is screw the lids back on again each time. No bench capper is required. I lose maybe 1 bottle per 1000 to undercarbonation and have never had a bottle infection. If it looks like there's crap on the lid I just throw it out. Similar sanitization applies to this method as if you were using a capper, although I'd ensure you sanitise the lids (if you don't already, some people don't sanitise crown seals)
I use a teatowel to screw them back on and you'll feel if the lid is slightly bent out of shape so ditch these. Tip the bottle upside down after sealing and you'll also see if it leaks pretty quickly. Obviously if you've used an opener to get the lids off you can't reuse with this method. I have a supply of about 250 bottles and caps that I keep reusing. I try to buy a new carton every 6 months or so to keep refreshing my supply.
Some brands work better than others. Coopers, boags, bitburger and the cheap aldi brand lager work well. I find some of the megaswill bottles, VB etc don't work, but who'd buy them anyway... Try to use the same brand bottle with the same brand lid but I've even used coopers bottles with boags lids sometimes with success. When I'm trying a new brand I test a couple of bottles at the end of a batch done with bottles I know work so that way I'm not risking a whole batch.
I find this much easier than a capper, the only equipment required is a tea towel.
EDIT: HB79, I've had some of these coopers bottles on the go for several years and have had no problem. Why does this thinner glass cause problems? Is it the capping itself that stresses the bottles (which is not an issue with the method I use)?