Thread on factory Remington sight bead?

[Stevo]

Lost the bead of my factory Remington 18.5" barrel this afternoon. God knows where it went in the snow. Does anyone know what the factory thread is?

Thanks.

 

[sunray]

6-48. Brownell's sells a Meprolight Tritium self-illuminated sight sight that replaces the bead for $36.99US. Kind of pricey. And a Lyman "ivory" bead with a wrench for $6.99US.

 

[Stevo]

Thanks, sunray.