Cleaning rusted steel

Hi all.
I have an antique cannon that had been left out in the elements for some time. The interior of the barrel has rusted and gotten pitted.
I have been using penetrating oil and a stiff wire brush to clean it and I've noted that rust is still being scrubbed out after a large number of cleanings. I was wondering if there is anything that you folks might suggest that would help break up the rust mre efficiently. I don't want to use a Naval Jelly type product.
I've thought of electrolysis but space and equipment are an issue.
Any suggestions?
Thanks.
ed
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please forget the chemicals - would use hones and manual speed honing via hand pistols/deWalt etc proffessional drills, to mechanically remove the rust. sure you may have to make up extension spindle drive shafts, but results will be well worth it.
there are many low cost honing sets available for automotive and hydraulic cylinder honing available + it is only a question of your time n patience required to hone in-out-in-et seq of bore.
stones can be rough - medium - smooth, but are low cost, so get a full set.
get honing. tell group if you need info where to get hones.
from sandy snipped-for-privacy@sacomet.com

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