Had this one out today and it looks like it has e/28 inpections on the gas shield. Rifle is mostly matching but does have an unserialed e/135(?) marked sight ramp and numbered but mismatched sight button. When I bought it I didn't look at the gas shield acceptances that closely but under a loupe they sure look like e/28, not e/26. Was under the impression that e/28 were armorer parts. Gas shield doesn't look like a replacement. Comments or thoughts?