The exact number of SMLE Mark I's produced by Enfield in 1903 is unknown but I can tell you it is at least 2,500. Most were upgraded throughout their service life, many like yours to an SMLE Mark I***. Value depends on condition as the Mark I*** is the most common early SMLE model. If it has been refinished post service its value will most likely be dictated by its shooting ability and yes, it is ok for commercial or Mark VII ammunition. Posting pictures of your rifle will help. Happy holidays!