If you're asking about 6RemBR then it's 350 for datum and best calculation is 1.1555-1.1565"? My datum chart shows 350, but calculated at 365. Datums are the same as 22br, 22-250rem, 6ppc and 6dash. If datum is 350, then it adds .0815" to 1.075". Geometry isn't my thing!