Quite a few apparently normal SMLEs do shoot very high - ie outside the normal range of issue sight blades. Sometimes it is not at all apparent what is causing the problem - especially if the rifle appears 100% to specification. The usual check list I run through is:

1. Vary the inner band screw setting (usually just affect group size);

2. Change the nosecap (can have a dramatic effect on POI and/or group size);

3. Replace rear sight leaf - even if the original appears perfectly normal.