Winchester has something serious going on. They have not been able to supply most of there premium hunting loads since before sandy hook. I don't know if it is because of government contract work or if they just tooled up to make more .223,5.56, .22 lr because of the demand a year ago.
I have not been able to buy a box of my hunting load for my 7mm(XP3 160 grain) for going on two years now.
Now it is impossible to find thier accubond and e tip loadings. For some reason the ballistic silvertips seem not to be affected.
One last place you can look is gunbroker.com, kind of the ebay for guns and related items. Its easy to register and buy.