Clearly a super late reply but... There is currently no way to delay/specify the frame brass is spawned. This basically sucks for any manually repeating firearm (bolt, lever, pump actions).
Not sure If I completely understand your original question about setting up the anims but just put the bolt throw as part of "end fire". The stock M700 is this way and my x9 M40 and M700 were like that as well.
For now, I've just been shortening the gap between firing and chambering motions to make the miss-match in brass timing less obvious. Essentially tie manipulating the action with "end fire" recoil and settling back to idle upon completion.
Gigabyte P67A-UD4-B3, Intel Core i7 2600K (passmark 8555), 16GB Corsair DDR3, EVGA GTX 970 SC (passmark 8637), Win10 Pro 64-bit, Primary monitor @ 1920x1080, secondary monitor @ 1280x1024