sorry I'm a little late to the party here. Jeff has given you good info. I would be a bit concerned as to the method of bluing used on the barrels. If hot blued ..bad...if slow rust blued...proper. A wealth of info here;
History of the Baker Guns » Baker Gun Web Site - The Guns of William H. Baker
From the pics it looks good. Now there were versions of this gun known as "black beauties" and the side plates as well as the fore end iron were blued. The case "hardening " is still there. The case "colors" are fragile and fade easily. These plates look to have been blued when the gun was refurbed. To re-case color it you would be looking at around $500 just for the annealing and re-casing. This would not count disassembly and re-assembly of the locks and the action. I don't know what you paid for this gun but I would hope that what we have just added up here for casing is more than you paid for it. I would really like a closer look at the barrels especially the flats on the bottom of the breeches to determine whether it is nitro steel or damascus steel. The "leaders" were listed as "twist steel" in the original catalog, but I have seen many with nitro barrels in my travels. If it has nitro barrels yes you can shoot it with low pressure loads. Available here
Polywad - Shotgun Shell Developer and Manufacturer - (800) 998-0669 These are 5000 - 7000 psi loads made for older guns like yours.
Bear in mind that off the shelf ammunition in that guns day was 5000- 7000 psi. Todays off the shelf ammunition is as high as 21000 psi. You may not blow the barrels up , but at the least you put a ton of pressure on the wood and on the barrel lug, and all the internal and mating surfaces. Quickly the gun will loosen up or go "off face" as we say in the biz. At the very least the stock will crack at the wrist as a result of the sideplates being slammed into the rear of the lock opening at pressure it was never meant for. It is a common break> I see it all the time on sidelock guns. Now add in years of oil soaking in the wood making it spongy and you have a broken gun. None of this is good of course. Send me pics of the flats and some good close ups of the area under the fore end wood, so I may be able to tell what type of barrels you have. If you are in my area anytime soon bring it with you and lets take a good look at her. You can come to my house if you like as I am not always at the shop. I hope this info has been helpful. I'm hoping for you that it is a HD Folsom marketed gun, that would give you "fluid" or "armor" steel barrels which are nitro proofed. Still you would need to shoot the vintager loads in it.