I also get that problem pete...its a PITA...
Ive not gotten around to a good fix yet...
im thinking of something matt black--maybe fuzzy track pants material--& rubber band around barrel...?
Ive noticed the position (forward/back) makes a difference sometimes...but ive also noticed the amount of moisture in the air also adds to flare--kinda like fog...
Ill let you know if i find a solution...& id also be keen to hear if you do/what you try...
The man who knows everything, doesnt really know everything...he's just stopped learning...