Drill M2 for optics rail

[Moondog]

I'm planning to drill M2 Field to add a Picatinny Rail for a 4x scope for deer hunting (specifically a UTG rail for a Mossberg 500 Rail). Does anybody have experience in drilling the receiver?

 

Are there any special considerations such as depth or bit type or size that I should be aware of? I'm planning on using an M5 sized bit and thread tap.

[Steve Rose]

I've drilled and tapped several of them. The receiver metal is too thin for a blind hole - so drill all the way through, tap, then trim the screws so they do not protrude too far into the inside of the receiver.

 

 

The receiver is aluminum... don't over tighten the screw and strip the threads in those holes!

[Moondog]

Since its aluminium, should I go with 4 holes instead of 2 or 3?

[Steve Rose]

Yes, more is better.

 

Since its aluminium, should I go with 4 holes instead of 2 or 3?

[Moondog]

Anybody have recommendations for a Picatinny or Weaver mount? I bought this one but the bottom is too wide and site astride the sighting grooves. My gunsmith says this and mounts made for round-top receivers will sit a few mm above the groove, which isn't secure because the screws won't have as many threads in the receiver.

 

All of the Benelli M2 rails I've seen are for the Tactical model with ghost ring sight and are too short. Or they appear to be for the SB models with a round top receiver.

Edited November 3, 2017 by Moondog