I have a question regarding headspace. My brass after firing 2 times is only reading 1.617". Using Lee Collet Die only. The same was true with my factory barrel in the same gun. SAAMI states as 1.634" (having 0.007 tolerance) . Chamber minimum is 1.632-1.642"(this is with the 0.02 tolerance). I am using the Hornady Headspace Bushing with my calipers

So my question is why might my brass reading 0.01" below SAAMI min for the case measurements? Is this normal? This was true both with my Savage factory barrel and now a custom Match barrel.