Thinking about a 10.5" upper. School me.

[ratski]

I'm thinking about putting a 10.5 or so upper.
This will be going on a RR Lower so I'm not looking at the SBR process, before anyone gives me dire warnings about SBRs.

I want a flat top so I can put optics on it.

Sounds stupid, but I see a lot of short flat top uppers with the standard AR front sights installed.

Seems to me that a short optic would be blocked by that front sight.

Am I correct in that?

Any suggestions on a good upper and where to get it?

Thanks

Dave

 

[henschman]

I'm thinking about putting a 10.5 or so upper.
This will be going on a RR Lower so I'm not looking at the SBR process, before anyone gives me dire warnings about SBRs.

I want a flat top so I can put optics on it.

Sounds stupid, but I see a lot of short flat top uppers with the standard AR front sights installed.

Seems to me that a short optic would be blocked by that front sight.

Am I correct in that?

Any suggestions on a good upper and where to get it?

Thanks

Dave

Depends on what type of optic, and how you have it mounted. Most people put red dots on ARs with barrels that short, as they match their capabilities nicely. With a red dot, whether it's absolute co-witness or lower 1/3 co-witness, the front sight is pretty much irrelevant. You don't even notice it when using a red dot properly. With magnified optics, the one-piece AR scope mounts that most people use place the center of the optic well above the plane of the iron sights, so the front sight is frequently not visible on higher magnification; or is, at most, a blur in the bottom of the field of view. I don't use those mounts myself, as mounting a scope that high compromises cheek weld... if the center of the scope is at the same height or lower than the front sight post, it will cause a blur in the scope and negatively affect image quality and your ability to see the target. So I don't have fixed front sight bases on any of my scoped ARs.

As for good uppers, DD makes a very nice CHF 10.3"... PSA has a 10.5" upper with a FN CHF barrel that is good quality. BCM is very good, but they don't go that short... the shortest they make is an 11.5". Also very good quality if you don't mind an extra inch. They claim it helps reliability. You can also get a lightweight barrel profile with them.

 

[Shodown]

The front sight does not necessarily block the view of a red dot. It will depend on how high the mount is for the red dot. If you put a red dot of some sort directly onto the flat top rail then yes, it might block it (depending on the red dot), but if you get raised mount (absolute cowitness or lower 1/3 cowitness) then it basically be in line with the front sight. Absolute cowitness = the red dot will be exactly in line with the front sight. Lower 1/3 cowitness = the front sight will be in the lower 1/3 of the red dot.

I have an LMT 10.5" MK18 upper with an A2 front sight on my AR pistol paired with a Primary Arms microdot mounted to an American Defense lower 1/3 cowitness and I really like it.



This pic should help as well:

 

[Cavedweller]

Depends on what type of optic, and how you have it mounted. Most people put red dots on ARs with barrels that short, as they match their capabilities nicely. With a red dot, whether it's absolute co-witness or lower 1/3 co-witness, the front sight is pretty much irrelevant. You don't even notice it when using a red dot properly. With magnified optics, the one-piece AR scope mounts that most people use place the center of the optic well above the plane of the iron sights, so the front sight is frequently not visible on higher magnification; or is, at most, a blur in the bottom of the field of view. I don't use those mounts myself, as mounting a scope that high compromises cheek weld... if the center of the scope is at the same height or lower than the front sight post, it will cause a blur in the scope and negatively affect image quality and your ability to see the target. So I don't have fixed front sight bases on any of my scoped ARs.

As for good uppers, DD makes a very nice CHF 10.3"... PSA has a 10.5" upper with a FN CHF barrel that is good quality. BCM is very good, but they don't go that short... the shortest they make is an 11.5". Also very good quality if you don't mind an extra inch. They claim it helps reliability. You can also get a lightweight barrel profile with them.

My 11.5" BMC SBR had no problem on the 500yd stage at the Run N Gun this year. I had a LMT 10.5" upper also that I was very impressed with.

 

[Mad Professor]

Dave,
What kind of optic and what are you going to do with it?

I always could only see one pro for a A2 FSB. They take a pretty good beating and still perform as intended. I was intrigued enough about your question to dig to the back of the safe and pull out a Colt 6920. I popped a scope on it and I was actually surprised on how little the front sight interfered. I’ve raised the backups on some of my others and they have seemed much worse. A lower 1/3 co-witness with 1x sights is not bad at all, but I prefer the cleaner view without it.

With a RR you might want to stay with a chrome lined barrel if you intend to run it in squirt mode much at all. Personally I’d stay away from the A2 FSB on a 10.5” to be able to run a longer uninterrupted forearm.

Here is the 6920 with my Meotac 1-4x mounted with a Bobro mount. That I tested. I need to try it again outside at 200 yards or so and see what it looks like.

Below are 9”, 10.5”, and 12.5” uppers with the majority of their usual accessories on it. I’ve been changing/testing some configurations and still don’t have everything just quite settled. Currently my hands down favorite is the 9” setup. 200 yards with the T2 is not really a problem if I do my part.

Rick

 

[CAR-AR-M16]

I have a Colt 10.5" barrel on an LMT flat-top upper with the fixed A2 Front Sight and an LMT Rear BUIS on my Mk18 Mod 0 clone. No issues with the Aimpoint. Iron sights appear in the lower 1/3 of the optic. Red Dot appears above. If the dot dies, it is an almost instant transition to the irons.

 

[Big50]

Noveske makes a nice 10.5'' upper.

 

[Big50]

I have a Colt 10.5" barrel on an LMT flat-top upper with the fixed A2 Front Sight and an LMT Rear BUIS on my Mk18 Mod 0 clone. No issues with the Aimpoint. Iron sights appear in the lower 1/3 of the optic. Red Dot appears above. If the dot dies, it is an almost instant transition to the irons.

Nice looking rig Car-AR-M16!!

 

[CAR-AR-M16]

Nice looking rig Car-AR-M16!!

Thanks!

 

[ratski]

Just wanted to say thanks to everyone that responded.

Gonna mull this over

Dave