buckstix:
there are two quite different types of rifling seen on manufrance guns...the previously mentioned RAYE which is similar to the english type of rifled bore (paradox, etc.)....it is a section of rifling that is smaller than the bore diameter ("choked"), and about three inches in length from the muzzle...it was intended to swirl the shot as it leaves the muzzle, to provide a wider pattern than a cylinder bore.

the other is what you have purchased, which MF called SUPRA (hence the S in the model designation)...it is an unchoked bore with shallow rifling that is the full length of the barrel...it was built to allow both shot and solid projectiles to be used...my example (12 gauge) has about .716 diameter lands and about .727 grooves, and rotates about 1/2 to 5/8 twist in the length of the barrel...it's not easy to exactly measure these barrels.

here's a link to a thread with some useful references;

https://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=492115&page=6

i suspect the gun you have bought may be the one i mentioned in this thread...these little french guns are neat and not easy to research...this site is head & shoulders the best place i know of to learn about them.

best regards,
tom

"it's a poor sort of memory that only works backwards."
lewis carroll, Alice in Wonderland