The "H" with arrow seems to be a fairly common mark. Though I do not know if it is a proof mark and a makers mark. ELG marked barrels only tell us that the barrels were made in Belgium, but it really does not tell us where the gun was made. England and France were not only making their own barrels, but depending on the time frame, were also buying barrels from Belgium and Spain. Like any value question, a survey of the rest of the gun would help determine value. Were these guns made as a percussion gun or converted to percussion? Only one bolt holding the lock on does not really tell us if it was always percussion of not as many times fowlers were made with just one lock bolt. If the guns are truly shot, they would have as much value as a truly worn out rifle, unless it has some known historical value. JMHO