I have a feeling your quest may be fruitless. The lightest bullet mentioned in Speer#13 is 325 and that was cast. Otherwise 350 is lightest jacket and that was HP.
Thing is, I suspect all bullet profiles will be effectively flat nose, so as to suit tube mags. I guess someone may make a full jacket flat point but yet to see one - and again - 300 seems to make a search even harder.
I am using Lasercast 405's in my loads - some for BFR but also including ''hotties'' with those thru #1 rifle.
Sorry no help.