chamber ring delayed blowback

[Les Snyder]

has anyone tried a chamber ring delayed system in their 9mm blow back carbines? I am referring to a shallow narrow annular ring, or taper,  machined into the chamber.... at initial max pressure the brass expands into the shallow chamber, then residual gas pressure forces the cartridge to the rear, which resizes the cartridge as it is pushed out the rear of the chamber... the resizing energy is used to delay the blow back... similar to the small chamber depression Seecamp used to retard the blow back slide in their .32

[Dannybot]

What does it do to the brass?  Is it reloadable?

[Les Snyder]

Danny.... at this point I don't really know... it should resize it as it is extracted...don't know about how much stretch

[Absocold]

Seecamp and Kimball pistols have used it, if the ammo is too hot or the brass is too soft the system performs poorly. Colt briefly gave it a try on some .38 Special gold cups but gave up on it.

 

The brass is reloadable but it gets worked an extra time (fire > resize > fire -vs- fire > chamber ring > resize > fire) so has a reduced service life.