I have owned a .243 since 1980 and have killed about 150 deer with...The first 75 or so fell to the 100 grain Remington CoreLokts...A few years ago I started trying different factory loads...This included the Federal Premium 100gr Nosler, 100 grain Sierra SPBT GameKing, the 85gr Sierra HPBT and the Classic 100 grain...In Winchester I tried both 100 grain soft point loadings, in Supreme and the Classic white box...In Hornady I tried the 100 grain InterLock...The Federal 95gr Fusion and the Hornady Light Mag didn't group well in my gun...

For longer ranges the 85 gr HPBT did very well, the Hornady also did well, but accuracy was so-so in my gun...When it was all said and done, I ended up going back to the CoreLokts, just because my gun likes them so well...

I'm assuming your shots will be on the longer side, I would start with the Hornady Light Mag as you mentioned, but would also try the Federal Premium 85 gr, sighted in 2 1/2 high at 100 yards, you should be 2 1/2 to 3 inches low at 300.