Bullets labeled .358" 180gr. TC-weigh170, which weight do I load for?

[dgang]

Uncovered a stash of ABC cast bullets from years ago. They are labeled .358" 180gr. TC but weigh 170. gr. Would a high alloy mix account for 10 gr. of weight? Do I load for 180gr. or 170gr.? Planning on using 13 gr. of 2400. Sound right?
Thanks in advance, dgang

 

[Texas10mm]

Alloy could make that kind of difference. Usually you see the bullets heavier than stated though. If there's too much tin in there that drops the weight quick.

Load for the 180 since it still has that much bearing surface.

In reality there's so little difference between 170 and 180 you could use either.....unless you're one of those fearless reloaders.