Yes.
While the hobbyist who is buying less than 5K of ammo (particularly in the 1-2K range) can still find lots of offerings in 5.56mm or .223 Remington, anyone making bigger purchases will have a hard time finidng availability and face significantly increased costs.
This started not long after 9-11 and has just gotten worse. The "spin-off" effects are out there, too. Because Winchester-Olin and Federal/Alliant/ATK both have either major military ammunition contracts or supplemental contracts, they satisfy those obligations first, which also cuts into there production of other ammunition.
Q3131A/XM193 is a good example. When Winchester had the contract to run Lake City (which Federal has now), when they satisied their military requirements for any given month, any extra production at the facility was ammo they could sell on the civilian market Military requirements, both operational and training, have increased so much that there is no EXTRA ammo being produced, except for stuff that doesn't pass QC checks (the infamous "PD" stuff). Additionally, these companies "civilian" ammo production is increasingly diverted to filling military contracts. Lead time on Winchester handgun duty ammo used to be about 30-60 days, more in an emergency. Now it is 4-6 months, with no real exceptions, because they don't make it as often becasue they are making MORE 5.56mm (I know this because we probably buy 50K a quarter). We have been trying to buy large lots of Q3131A for over a year now, and it just isn't available, particularly since all of our purchases have to benchmarked against the state contract (which lists non-FET Q3131A at about $130/1000) and the low bid on contract has not honored any POs for Q3131A for the last year. Duty 5.56mm (if one wants fancy stuff) has about a 6 month lead time. While you personally can walk into Sportman's Warehouse or Cabela's (or go to an online seller) and buy 100 or 200 rounds with no trouble, try buying 25K, drop-shipped from the manufacturer. You are going to wait a while. You are NEVER going to get a big order of Q3131A or XM193. We have actually gone to buying from the military, and our lead time is still a couple months.