Putting the orange XS big dot sight on my Mossberg 500. I'd also like to have the receiver milled so I can install a dot too. Any possible way for me to install a dot and still be able to use the front dot?

Any higher rise mount should allow you to cowitness fine.  The stock Sig Romeo 5 red dot mount cowitnesses fine.

I don’t think you can cowittness but with a high riser you can look under the red dot sight. You might be able to cowittness with a Burris speed dot but I haven’t found the speed dot to be very stable.

Doesn’t sound cost effective

Probably $250 to $350 to mill flat plus a plate plus the optic …

Take a look at the Williams LRS (Low Reflex Sight).  It is designed to sit pretty low for this purpose.  I don't believe any milling is required to get it to co-witness the front sight.

Edit, I just realize you said XS big dot, I was thinking the ghost ring front.  I'm not sure if this gets low enough.  

Mossberg has a new pre-milled gun that can use RMR pattern sights.  It may be cheaper/cleaner to get new guns and sell your current setup.

Not worried about co-witness. Just don't want to lose the ability to use the front sight

I just saw this from Defender Tactical.  It is a mount for an RMR pattern cut optic and has provisions for Glock sights to co-witness with the optic.  It isn't pretty, but it looks like it would work.

https://c8sxz297bjc3lpmb-60962373811.shopifypreview.com/products/cosight

Defender Tactical really specializes on the Mossberg pump shotguns, particularly the Shockwaves.  They make a semi-permanent adapter for the Mossberg pumps to use short shells that doesn't need to be removed to use standard length shells.

I would assume there is something out there for mounts.  I'm using an RMR with my Benelli M2 on a Scalarworks mount and it's a direct cowitness with my front sight.  So basically if the sight died there wouldn't be a problem.


Attached File

I've heard this one mentioned a lot but I have no idea if it works with existing sights.

https://www.burrisoptics.com/mounting-systems/speedbead-mounts

Scalar Works is going to be your best bet. No need to mill anything you receiver should already be drilled and tapped. https://scalarworks.com/shop/integral-mounts/sync-03/

I’m not 100% certain if you will still be able to retain the use of your front sight with the dot mounted because various optics are various heights and I believe the XS Big dots on the Mossberg guns is barrel mounted so it sits lower than the XS sight on say the 870 which is on a pedestal. I’m not sure what the concern is but if you’re worried about losing the sight in a fight and thinking you will need the front sight, you won’t really. The optic window will kind of work like a pseudo ghost ring sight. Put the target in the center of the window and fire. It’s not going to be super precise but it will be plenty fine under the circumstances. Inside of 25 yards it will be minute of man for sure.