Allen key size for keeper bolts on LaRue Quad Rail Handguard?

[jlow]

Seems like none of my hundred odd Allen Key seems to fit these bolts . Please forward info if you know - thanks!

 

[jlow]

Thanks a bunch! It's interesting, I've tried all my hex head bits with no luck, and also looked on the web, seems like a 8/32 hex head bit is a bit of an odd ball? Am I missing something?

Sorry, looks like I missed your comment about a 9/64 hex wrench. Will look for that.

 

[jlow]

Git them off thanks!