Blitzen grub screw size

[45root]

So I picked up a couple of blitzen RTAs on clearance this weekend. On one of them, the grub screw just seems to almost get tight enough and the it seems like it just goes through. I need a longer screw than the stock one. I'm guessing about 1 or 2mm longer so the barrel will still for down in the grooves. Does anyone know what size they are?

TIA.

 

[uthinkofsomething]

Many are 3mm screws, but I don't know. Take it to a hardware store and match up the threads. Don't go too long...

 

[RudeRoo]

The stock screws are m2.5 x 3.
M2.5 x 4 is perfect.

Screw on the left is stock.

Stock screw on the right.

 

[45root]

Thanks for your help guys. @RudeRoo that's exactly what I need.