"Concentrated Nitric Acid", whether reagent grade or technical grade, will be about 70% nitric acid, by weight. To use it to dissolve silver, dilute this with an equal volume of distilled water. This is what we refer to as 50/50 nitric. Although any strength of nitric will dissolve silver, 50/50 nitric works about the best, for various reasons.
Two gallons of 50/50 nitric (one gallon of nitric + one gallon of distilled water) will dissolve about 100 tr.oz. of silver. Metrically, one liter of 50/50 nitric will dissolve about 13.2 tr.oz. (410 grams) of silver. One liter of 50/50 nitric will also dissolve about 117 grams of copper. These figures are never exact but they are always quite close. They are affected slightly by a number of variables, such as temperature.