While it's only hearsay, I know a fella who's been shooting it for some time in some very early English guns and he's quite happy with the results.
The costs (when compared to RST) appear to be substantially less as well (IIRC they apparently absorb the shipping?).
I've gone through at least 3 cases of the 12 gauge by Armusa low pressure, they shoot good. Maybe case and half of 16 gauge.
If you buy at least $500 of shells from ClayAmmo.com It's now ammofix.com (I think they are the importer and primary distributor) the shipping is free. At least $6 per box cheaper, maybe a bit more.
While they may be Cheddite style hulls or even Cheddite's with the ARMUSA headstep, I'd rather not guess, hence my original question.
The price is currently $165/case ($10 flat rate shipping per case. More than $500 free shipping) for the low pressure 12 gauge which is 1 oz @1170 and a listed pressure of 6100 psi. It went up $20 since my last order maybe last May or June. Cheapest RST by the case is $230.00