The only time I choose the Garand over the Springfield is when US is Army instead of Marines (why can the Army even equip Springfields? Hadn't they replaced the 1903A1 before Guadalcanal?), though I would prefer if we were issued 1903A3s for the post-42 maps.
Anyway, I found that the best thing to do is be very VERY conscious of range. If they are within 100 meters, you want the top of the spike to be about level with their temple/forehead. This is generally the same if they are at 150 and you're zeroed for 200. If they are at, say, 85-115? Top of the spike, it works perfectly. One thing to be aware of though, and I've seen this a dozen times, sometimes they duck right as you're firing, or they move a bit or some such. Just the other night, I was playing on Kwajalein, plinking off japs in the trenches and not 10 times did some jap turn or duck or what-have-you right as I had the trigger squeezed and it threw off my shot.