44 280 Keith .434I like this one. Yes, I know it's not 300 grains but it has a WFN meplat, no gas check and if you have an older Smith, like a 29-2, it can be sized to fit the throats. The H&G 503 is another good design, with a smaller meplat.
I have piles of 300gr. 44 caliber molds, but the utility of an "every day" bullet weight of 300grs. and something like a 300 WFN or WLN Lbt mould or shape like to be leaned on for best accuracy. They also are a bit too much in a 44 Special. Any true 44 fan WILL own a 44 Special or two.
The 280 has the SD of a 300gr. 45 bullet, give or take, works well with lighter loads and depending on the Smith gun they (300's and larger) have a tendency to run out of front sight height with moderate loads or even heavy loads. The 280 is a good compromise without giving up anything and getting you a bit more out of your investment instead of more of a one trick pony. LBT did make a nice 280 WFN 44, but the Keith one above is still more flexible and I doubt any bear would keel over with a stiff load with a 280 versus a 300. The 280 can be driven a bit faster with like bullet profiles.
