I'm a reloader...so I don't buy hardly any ammo / but a lot of my buddies search the cheapest stuff out all the time...and they have good and bad experiences with a lot of different outlets.
I am very confident in my own reloads...my procedures...quality control, etc....but out of all the guys I know that reload...way too many of them do not use very good controls. Just look at some of the questions on the reloading site on this forum...it can get a little scary on what folks think is acceptable.
In general, there can be issues with re-man ammo....and while some of it alledgedly is "company re-man ammo"...in my experience it is often from a 3rd party they they hire to re-man it ( some guy in his basement often), and their contract requires the 3rd party to have commercial general liability insurance, which they rarely have - and most mfg's ignore it. To rely on insurance to help you if you have a problem ...on new ammo / or re-man ammo is probably a stretch ...because often it will come down to an investigation into circumstances and whether shooter error contributed to the accident. It might be very hard to prove it was exclusively an ammo related issue. Just because a guy has a website selling ammo...doesn't mean they have insurance - let alone good insurance. Homeowners insurance....in most states....does not give the homeowner any liability for business interests, like reloading ammo for sale - whether its profitable or he is just breaking even, does not matter.
If you are going to buy reloads...buy based on word of mouth in your area. If guys are buying enough of it ....or shooting enough of it ...and they say its ok, its probably ok. If you start having misfires, any squibs..etc...its time to find a new supplier. At the same time...every now and then new factory ammo will have issues as well.../ so to some extent its part of the hobby to unerstand and accept the risks, especially if you buy re-man ammo.
My best advice...learn how to load your own / buy ammo from businesses in your local area that have a real brick and mortar operation if you want to buy re-man ammo and pick them based on their local repuation word of mouth recommendations / or buy the least expensive factory ammo you can find in case lots...Federal white box, Blazer brass, etc...
Understand your guns warranty...many gun mfg's do not warrant a gun if you use reloads...