As I understand, I don't know whether this came from Alex or Morris, any information printed about pressure figures can change on short notice and then be not as accurate. RST actually has their own pressure testing equipment (a fairly recent development) and don't have to send ammunition out for testing. I would imagine every large lot of ammunition is tested for velocity and pressure, resulting in minor differences. Email or telephone inquiries will result in the most recent and accurate information. I'm sticking with the RST products because of the variety of short chamber and low pressure stuff, the stuff that I use the most. I wouldn't know where else to go for ten gauge low pressure ammo for Damascus guns.