I think the big prblem would be sizing the bullet. Depending on the saturation of the meat, the bullet could expand up to 5% when frozen, and may not fit in the case. I suppose you could cast the bullet, freeze it, then size it and freeze it again.
There is the consideration that the bullet will be very low density compared to lead. Since "meat" in general is not homogeneous, the center of gravity may not be in the geometric centroid of the bullet, so it will not likely be too stable in flight. Also, with the low weight, the bullet, if it stays intact, may not be carrying enough energy at the point of impact to penetrate anything. Ugh. A meat-splat bullet.
I don't see any special problems with the basic concept, but it will definitely take some experimentation to perfect. If you are able to make it work, the groundwork is laid for all manner of body fluid and semi-fluid bullets. Blood bullets, poop bullets, toe-jam bullets, earwax bullets, booger bullets ... If you want to stick to food, you could try Spam, candy, gum, black-eyed peas, blueberries, Grape Nuts, peanut butter.
What do you clean your barrel with afterward? A-1 Steak Sauce? Or do what I do after eating a steak: soak up the juice with some bread!