I've handled this "new" Barrett and am very impressed. Changing calibers in this weapons system is pretty easy even in the field. I believe the phased roll out is done for reasons that relate to rifle caliber and purpose. Similarly, with the full roll out, there are a number of benefits that are expected. Here are just a few. The new Barrett (in any caliber) is much easier to shoot, by more riflemen, than the 50cal big brother. Ammunition is lighter which is a huge benefit to the soldier on foot. The 7.62 round is a great choice for SDM (Squad Designated Marksmen), while the larger calibers are well suited for more specialized marksmen and missions. If a rifleman is familiar with the new rifle platform, of any of the three calibers, he/she will be familiar and pretty proficient with the others because the chassis and action are so similar. Would I expect a rifleman to carry rifle barrels/bolts into the field. No - but they (squad, company) would likely carry "identical" rifles of more than one caliber. I can imagine the 7.62 for close in overwatch, the .300 and .338 reserved for vehicle/building/barrier penetration, or shots >700 yds. Would I expect a soldier to change barrels/bolts on any given rifle? No. But the armorer will. Lastly, successfully managing two or three weapons with differing DOPE is not a problem - especially with today's electronics.