I have never had an issue with steel cased ammo in anything I shot. Some have had major problems in high round count rifle classes with stuck cases and so on. Wolf/Tula are however very dirty ammo compared to others with Tula being the worst. I do not know what powder they use but from the smell of it there is a cat box or pig farm involved somewhere.
I do shoot quite a bit of Silver Bear with is basically Wolf/Tula type ammo but the difference is that it has a zinc coated case which seems to eliminates the stuck case problem. My rifle has a fail zero upper so cleaning is not a big issue with whatever I shoot out of it.
I buy my ammo from J&G Sales. Good prices, quick shipping and they always have something in stock. I have purchased ammo off gunbroker also just read the fine print. Every once in awhile you will find someplace that offers free shipping for "X" number of days on certain amounts.
I don't like Tula ammo. It is super dirty and, to me, it almost feels like double the round count when I clean up.
I shoot tons of Silver Bear and Wolf ammo with no problems.
I love Wolf Military Classic... it's the same thing as normal Wolf WPA, just made in another factory from what I have read.
If you look you can get it cheaper than Tula, which I do not like.
For SHTF..... It's more expensive, but it's gotta be M-193 for me (Federal XM193). It's 5.56 and uses the correct bullet and velocity to still supply sufficient effectiveness on a target. Some .223 rounds will fragment and make for an OK defensive round in a pinch. But M-193 is more consistent with the added velocity and correct bullet (some .223 rounds do have a cannuluer).
I have 3 mags loaded with Mk318, MK262, and 75gr TAP. The rest are M-193, mainly for range use, but can be used if absolutely needed.
For simply just going out the range and shooting, any of the steel cased rounds will be fine as long as they run in your gun. I like PMC as a cheap, brass cased .223 option.
There are some places that had low price sales of British or Australian SS109 55 grain rounds. Those rounds are under loaded so they cycle better in the rifles the Brits and Aussies use. But they are under powered compared to the M193 and M855 62 grain green tip US ammo.