Folks have asked if there is a tool that can remove obstructions from a Lapua small, BR-sized flash hole without opening the hole size. The Lapua PPC/BR flash hole is spec’d at 1.5mm, which works out to 0.059055″. Most of the PPC/BR flash-hole uniforming tools on the market use a 1/16″ bit which is nominally 0.0625″, but these often run oversize — up to 0.066″.
If you want to just clear out any obstructions in the flash hole, without increasing the flash hole diameter, you can use an inexpensive “pin vise” with an appropriate drill bit. For $1.00, eHobbyTools.com sells a 1.5mm pin vise bit, item 79186, that matches the Lapua flash hole exactly. Other vendors offer a #53 pin vise bit that measures .0595″ or .060″ (depending or source). An 0.0595″ bit is close enough. You can find pin vises and bits at hobby stores.