only blackpowder?
 

I have this old shotty,a side by side 16 caliber st-ettiene,a family heirloom that belonged to my great grandfather ,I started black powder shooting in 1990 and since then the shotgun is back in practice,no need to say that I only reload with Black Powder,but always asked myself if its ok to use it with modern shells,?can anyone tell me what the numbers on the barrel stands for?
http://img842.imageshack.us/img842/4729/1002924.jpg
http://img839.imageshack.us/img839/9711/1003044q.jpg

I can't tell you what the numbers mean but it has the standard nitro proof. However it won't be chambered for 2 3/4" shells. More likely 2 1/2". At any rate I would stick to black powder with it and take it easy on the old girl. BTW St. Ettiene is a city not a manufacturer.

thank you Hawg,I will stick to black powder use, so I don't have a St. Ettiene
it's made in St.Ettiene, thank's

I don't know if you're buying bp shells or reloading them. If you're reloading you need to cut modern shells back because the star crimp will open over the forcing cone causing undue pressure. Since the gun is nitro proofed that likely won't hurt anything but it will pattern better if you get the crimp back behind it.
I cut my 12 gauge shells behind the crimp which only gives me a total of 2 1/8" then I roll crimp them after they're loaded. One of these days I'll break down and get brass shells from Magtech.

This probably isn't the preferred answer but for each of my antiques I'd have a newer/less valuable counterpart to mess around with.

Shell length will be an issue. I have GOT to get a better monitor, but think you have a marking of 66- believe that is your chamber length in mm- or, as the man said, about 2 1/2 inch shells. St. Etienne is the city where the French proof house that proofed your shotty is located. PT and Crown is nitro powder (smokeless) symbol. Means tested to 960 kilograms/ square centimeter. http://www.phoenixinvestmentarms.com/archives/Proofmarks.pdf

thank you for the very interesting site of the proofmarks ,I never felt sure about using modern shells,I still have a lot of new ammo, I prefer to shoot it with Black powder,its just a matter of having an uninvited guest in my house and that I don't have to look for the blackpowder shells but can use any shell I find
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Scratchammo,I like it when people give their opinion on this thread ,and I understand your point of view, I shoot it but not on a regular base ,just like in the US whe also have "historic gun" shooting discipline, I had an original ,snider enfield"sargent's type",remington rolling block,martini henry and enfield musket,al guns where in superb condition and I fired them all

Hawg ,I know it may sound weird ,but I use the original shells I take out the new powder and replace that with black powder,that's been done for twenty years now and never had any problems

Understood :) I'm just paranoid about using my old Antiques. We have an old Springfield 1861 & a duplicate from Taylor's that I shoot often. The original is for show. Did you get rid of them?