It needs a little further digging before you plunge. 950 bar is the proof pressure, service load would be @ 750 bar. That would preclude any SAAMI Ammunition. FYI most Spanish 28 ga guns coming to the US are proofed at 1300 bars/ 1370 Kgs/cm/2 Call Birmingham Proof House to discuss and ask about off the shelf 3/4 & 1oz loads to US specs.
As I understand the system the Brits were using with the "bars" marks, those were lead crusher readings rather than transducer. Back then, per the Birmingham Proof House, the CIP standards for the 12ga were 850 bar proof and 650 bar service pressure--but converted to transducer, the equivalent readings were 960 bar proof and 740 bar service pressure, the latter of which works out to 10,730 psi transducer. If service pressure for the 28ga based on 950 bar (crusher) proof is 850 bars (transducer), I come up with a service pressure of 12,325 psi--which is just under the SAAMI standard of 12,500 psi for the 28ga. Close, but probably worth checking with the Proof House to see if they recommend standard SAAMI ammunition.
