Granted that the choke must always reach the end of barrel and get fastened
to it by the internal diameter edge, before you mount it, accurately check
that it is not damaged each time, particularly the final diameter (internal)
that goes into the bar.
When using, it is better to check the tightening, since the chokes should
always remain locked to prevent gases from entering between barrel and
chokes (most common problems of broken reeds derive from this).
When you don't use your rifle for a long time, disassemble and clean the
chokes and its housings and, before reassembling it, we recommend to lubricate
it with some special grease, resistant to high temperatures.