http://tradetools.co.nz/products/2850100
Blow the 556 out with the compressed air, warm the area, spray the PB blaster around the stud root and leave it a couple hrs.
Also, whereas usually an impact driver would be the go, over that length it'll be less effective. A bunch of light smacks on top of those nuts with a half pound steel hammer would probably help though.
Oh, and if you're going to put stainless nuts on stainless studs use a liberal fingerfull of high nickel anti-seize paste on the thread.
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