What stops the bolt on a Darne shotgun?

[Colt Fanning]

Howdy
I have a Darne shotgun in which the bolt slides completely off the gun.  What stops the bolt on a Darne.  The safety is missing and that may be the problem.
Regards
Colt

[Coffinmaker]

Unfortunately, your Face and be instrumental in stopping the darn bolt   

Hide and Watch

[Professor Marvel]

My Good Colt Fanning -

I fear that more information is necessary for a correct reply... BUT

If you mean the Sliding Breech Darne Double Shotgun, this page can offer an explanantion of how
the lever operates a bolt to hold the breech on place

https://www.gunsandammo.com/editorial/french-masterpiece-darne-v22-28-gauge-side-by-side/249810

hth
prf mumbles