I was going to go to the range and shoot it some more today ,but it's raining and I am just getting over being sick so I stayed indoors this morning and took the Arez Rex Zero one completely apart. Internally there are a lot of differences between this pistol and a Sig Sauer P226 series style pistol. If you are not one who can deal with tiny springs ,pins and ,detents then this is not a handgun that you should disassemble. It was not hard to get it apart,it's just got a lot of small parts that if lost your not going to be able to replace them easily. If I want lighten the DA pull I am going to need springs from another pistol outside of the Sig lineup. The mainspring is longer than a Sig mainspring. Another option if i want to use the Sig 17 lbs Bruce Gray spring would be a custom spacer to make up the difference. I really don't want to spend time making a spacer,so I came up with another option , a CZ 75 16 lb Wolff mainspring. Its a little to long so I will cut it to size reassemble and take some trigger pull readings. The SA pull from the factory is quite nice already, so it really does not need to be lowered. The DA pull is too heavy over 12 lbs and that is what I want to lower it. So if all goes well with the swap and shop testing I will go back to the range and do some test firing for function.