Bullets don't "Tumble" thru the air..
Some rounds like the 5.45x39 (Read what Jsarclight wrote about ak47/74) were designed to have a yawing motion/tumbling effect... But that's after they enter soft tissue.
To be frank..
After a couple of years of collecting Macross toys I've kinda burnt myself out..
I'am thinking of buying a few more 1/48's and then taking a break until atleast spring.