My wife who should know better (ex national squad), a month or so back had several of us trying to clean out hairs from her back site for half an evening! Nothing there, just the hole was too small for her eye relief. Either get the rearsite a tad closer or buy an adjustable iris.
Its also similar to the post earlier this week, (Can anyone help from Dave Palmer) so have a look at the answers on that.
Good Shooting
Robin
Walther KK500 Alutec expert special - Barnard .223 "wilde" in a Walther KK500 Alutec stock, mmm...tasty!! - Keppeler 6 mmBR with Walther grip and wood! I may be a Walther-phile?