My dad has always shot a 243. 100 grain and he loves it. I may be purchasing one for my wife this summer for deer season.
I grew up hunting with a Marlin 32spcl and it is still the only deer rifle I own. I love it. I feel comfortable shooting up to 175yards , and it does great at close range and is a good brush gun. Plus its lever action so it makes me feel like a cowboy!
As far as a 300 Win Mag, they are quite popular in central FL where I hunt, open palmetto flats offer long distance shots(although only few guys are capable of making them), and it is very hard (nearly impossible)to pattern where the deer will travel through these palmetto fields so the extra range is great. This will be the next gun I purchase.
I believe shot placement is more important as far as ruining meat than the caliber of the gun.
And to answer your question I wouldn't want to use anything smaller than a 100 grain 243.
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