You have a very heavily modified No4 Mk1 Lee Enfield. Biggest change is modification of the action to fit in a one piece stock, this is major surgery. Someone invested a lot of time, and perhaps money, to do this. Overall a nice rifle, but not particularly valuable in this day and age. It used to have a scope, but is now missing the top portion of the base.
You're obviously quite young, 30 year old ammo is not old. If its commercial soft point eg Winchester, Remington, Federal, Dominion, its not corrosive. Go ahead and shoot it, with the usual precautions. BTW - The safety is engaged, surprised you can manipulate the bolt.