Need help Identifying This Lead Cast Bullet

.301 is an odd size.

Here's a chart of Lyman molds. http://www.three-peaks.net/bullet_molds.htm

I'm not saying it's a Lyman but it gives you an idea.

Do you know by chance what guns he owned?

Those look like they were cast with an old Ideal Mold? I checked an old Ideal Catalog no match?

Since you mentioned Grandfather,just going to throw this out there after taking a ride in the "Wayback" Machine .Looking in the "Ideal Hand Book" No. 36 (6/49) page 74 shows a bullet (308403) as being 172 grains with the first 4 bands measuring .301". 5th band .303", last band @.315". Designed by Mr. Harry Pope, a target load for competitive shooting in the.30 Springfield rifle.

It could be a cast bullet for a 7.35 Italian Carcano. I don't know who made the mold.

170 seems a little heavy for that cartridge. However with the gain twist rifling in the Carcano, it may have worked.

Recheck your measurement. If you acidently measured in the groove you may get .301 for a .308 bullet. Could be just a standard 170grn for a 30-30. Just a thought. Just checked and gpb might have the answere. The 7.35x51 Italian Carcano was a true .30 cal so these could be sized down for that. Heres some info. Scroll down the the 7.35.
http://personal.stevens.edu/~gliberat/carcano/emary.html

Its in Ideal Handbook 30 too. The drawing looks exactly like the OP's pictures. Its listed at 172 grs.