I have the Vortex prism 3x that I’m mounting on a rifle with a fixed front sight. It has a pop up Magpul rear. I’m thinking of just leaving it on, maybe even mounting the optic over it. It wouldn’t cowitness or be usable anyhow. The optic is not on a quick mount - maybe one day.

Seems a bit odd, but it’s not needed on another rifle.

Absolutely keep it on there. It would be far odder to remove it. QD optic mounts aren't a requirement for retaining a BUIS. I am sure your optic can be removed easily in the field with a multi-tool that you ought to have in your kit somewhere.

There has been such a strong push against BUIS lately, even on pistols. I don't get it. But, as with everything ever, everyone's uses and requirements of their equipment, and personal preferences, are different.

EDIT: I am not sure your optic can be removed with a multi-tool. My current setup on my "go-to" has the irons in an unusable condition unless I defeat a pair of allen bolts or a Larue VFZ mount, neither of which is easy with a multi-tool. I have the required allen key and Larue wrench in a tiny ziplock, in my utility pouch.

I specifically mount my Strikefire II far enough forward that I can still flip up the rear buis.

If it’s not in the way and not needed elsewhere, why not leave it in place?

If you ever remove your primary sight, the backup would be there.

quote:

Originally posted by sigfreund:
If it’s not in the way and not needed elsewhere, why not leave it in place?

If you ever remove your primary sight, the backup would be there.

Yep.

All good and then when your primary optic falls off the gun for reasons you didn't anticipate you are good to go...

My Sig M400 AR has an ACOG 3.5x and BUIS, but I cannot flip-up the BUIS where I currently have the optic mounted, but where I shoot it best. I keep the BUIS in-place because if I need to remove the ACOG I still be able to shoot it. (Okay, in fairness, I have thought about removing the BUIS).

I currently have one rifle with a fixed front site and yes I left it on with a backup folded down Rear buis. My scope can quick detach, but I would have left it regardless. It’s not hurting anything and not in the way.

The other possibility is you take it off, can't find it later when you need it, then buy another one whereupon the second you install it you find the old one.

quote:

Originally posted by k:
The other possibility is you take it off, can't find it later when you need it, then buy another one whereupon the second you install it you find the old one.

I hate it when that happens. Yeah, I've done it. Found the missing part the next day.

On the thread topic, my AR carbine is set up and zeroed for either an RDS or a scope. The RDS requires a Torx wrench but the scope is on a PEPR QD mount. The Magpul BUIS sits, folded, under the eyepiece of the scope so I would have to pop the scope off to use the irons. The RDS, I mount far enough forward that the BUIS is usable right through it. Can't do that with the scope due to eye relief limitations (can't see the front sight through the scope anyway, so either way the scope has to be removed to use the irons). The RDS is actually moderately usable as a ghost-ring type rear sight itself, albeit a pretty big one.

I've got an AR-10 that has a flip up rear that I wouldn't be able to deploy unless I ripped the scope off. It's not in the way, zeroed to the gun, and will be there if I ever need it.

On my AR10, I opted for a little level, where the rear sight ought to be. Still zeroed the irons with the rear sight mounted just ahead of the level, then removed it an attached it in the stowed position, just ahead of the front scope ring. In that situation where the optic is rendered inoperable, I have the tools to remove it and reposition the rear iron sight. I am not talking about doing this "under fire". You'd have to use a more improvised aiming technique, or employ a sidearm, until you're able to find a safe situation.

All my rifles have scopes. I've never removed any of the sights unless they interfered with the scope. For example my LMT MWS had to remove the huge rear sight to mount a Nightforce scope.

As an update, the rear sight came off. The Vortex 3x benefited from being closer to the eye. This was the gen 1 not the gen 2.

All of my AR’s have NF scopes in NF Unimounts. All of my AR’s have BUIS.

I keep a 1/2”, cut down, box wrench in my cleaning kit.

Yea, on my AR with a vortex scope on it but I have the scope on a QD mount so if the scope gets damaged it’ll be off the gun in seconds and back up irons are there. I’d suggest getting a QD mount for your optic. Never know when an optic will go to shit on you and you don’t wanna be caught with your pants down

quote:

Originally posted by Oz_Shadow:
As an update, the rear sight came off. The Vortex 3x benefited from being closer to the eye. This was the gen 1 not the gen 2.

Honestly, the Gen 2 Spitfire 3x isn’t any better with eye relief. Actually, it’s a little worse, according to Vortex (2.6” vs 2.8” for the Gen 1).

Whenever I have a flip up rear sight that’s unusable because the rear of scope blocks it from deploying, I always get a QD mount for the sight. American Defense makes one specifically for the Vortex Spitfire 3X.