- That very hot & rapidly expanding gas that leaks from the flame-front at the cylinder gap in revolvers is nasty stuff - and is on record for having caused serious injury to shooters who put their digits in the wrong place - but I'm not going to show any meaty images here.
There was an early(ish) partial fix for this dangerous flame cutting leakage - The venerable maker Iver Johnson patented their Flash Control Cylinder in 1954.. Their cylinder was recessed at the front face to provide a rim or flange that deflected leaking gasses and any lead shavings forward and away from the shooters hands - indeed it also protected any close bystander from being 'peppered'.
- You would have to have a gap in the rim to allow the cylinder to clear the barrel when unlocked .. Derr.
The other well known answer to that cylinder gap problem is of course the Nagant 1895 revolver that was made in Russia for many years in 7.62x38mm - starting at the Tula Plant in 1898.
Empty Nagant Case (top, left) With Loaded Round.
This .32" calibre Nagant revolver gains a little muzzle velocity by eliminating this gas leakage - by having a reciprocating cylinder that pushes and seals its special cartridge deeply into the start of the revolvers barrel where it obturates.