Hopkins and Allen made large quantities of shotguns, rifles and revolvers in the medium quality price range. They made revolvers in both single action and double action. Most of the single action ones were of the inexpensive spur trigger variety in .22 and .32, but they also made decent quality SA revolvers in .38 and .44 rimfire. Their "trademark" on their better quality guns was "XL". When they acquired Forehand and Wadsworth they continued to make that company's Bulldog revolvers, in .38 and .41 center fire, adding the "XL" and their own name.
A picture would help, but I think your gun is double action, similar to English "bulldog" revolvers, with swingout loading gate, and an extractor rod that swings out after being pulled out from the center pin. The center pin comes out to allow the cylinder to be removed. Most were nickel plated.
The gun should be safe with the .38 S&W cartridges that it was made for (including modern factory loads), but don't try to increase the power with handloads.
There should be a front sight; either it has come off or the barrel has been shortened.
Jim
