You might be to essentially use your modern equipment as a store of magic, though. Let's say a 7.62 round takes a minute to produce magically, you now have a machine that can send the output of 10 hours of magic downrange in 1 minute. Even assuming quite a lot of loss, that could be potent depending on how your universe works.

If you know how your equipment works and can find the right smiths, potionmasters, etc you could essentially be carrying the templates for the most powerful items in the realm. Or useless wunderwaffe.