I frequently weigh bullets to see their manufacturing consistency. Most (even high quality brands) vary up to +/- 1.5~2 grains from their nominal weight.

Yesterday I took some 90gr XTP and filled the cavities with DAP window and door caulk. The one bullet I weighed afterward was exactly 90.0 grains. Now to see how they expand in water compared to regular XTP at 930 fps from a .380.

DAP advertises that it stays flexible and a typical life of 15-20 yrs, so I don't expect it to 'harden' in storage, at least till I shoot them. This concept provides multiple testing opportunities to shoot more - different fillers and different brand bullets... all in the name of science of course.