One thing is for certain, Remington wasn't making any ammunition during the shortage until Vista took over. Additionally, even BEFORE the bankruptcy, Remington was making little ammunition due to lack of capital to acquire raw materials. I have a friend who is an engineer for Remington. He stated that the day Vista became the official new owners, the components started flowing in. It didn't take long for them to get up to full capacity.
Regardless of perceived monopolies or not, Vista's acquisition of Remington ammunition has increased supply for the consumer and prices are already coming down. At the local Academy Sports earlier this week, there were full shelves of .308 Win, .30-06, .270 Win, .243 Win, and .300 Win. all in Remington for $23.99 to 28.99 per box. It was much cheaper than the Winchester, Federal, Hornady, Norma offerings that were sparsely available.
As to whether or not Vista holds a monopoly, there is Winchester, Black Hills, Hornady, Berger, Sierra, Nosler, Armscore, Barnes, Magtech, and several boutique or specialty makers. Vista holds Federal, CCI, Speer, and Remington with CCI only making handgun ammo and rimfire, while Speer makes handgun ammunition. Only time will tell if it is good or bad for the consumer, but at this time it is a GOOD thing Remington is running up to capacity.
At this time, I have not seen any evidence of market manipulation by Vista. If anybody has any evidence they are doing so, I would love to take a look at it.