Go easy on me, only owned 2 ARs in my life.  Currently have a Olympic Arms K16 flat top, heavy barrel with no front sight.



I'm a lefty, so I'm considering getting a Stag.  Here are my 2 choices:



Ultimately, I plan on putting a red dot on there.  I really don't know enough about co-witnessing, back up irons, etc.  



So, for just a general shooter, home defense and a little 3 gun, what would be better, the fixed site upper, or adding a flip up front sight to the second option?



This







Or this

Honestly I'd rather hear the 'pros' of a removable front sight.

I've never found a 'con' with a fixed, with or without a magnified optic.

So if I may ask a very stupid question.



When you have a red dot that's co-witnessed with the front site, do you find it hard/slower to get your sight picture lined up with the dot/front site post/target?



 

Only cons I can think of:





Gives you no red dot options other than some form of co-witness.


Does not allow you to easily swap in different sights such as a Tritium front sight.





Otherwise, yeah, pretty much no real cons.



Personally, I prefer a rail block, so I have the options to try different configurations, but its just a personal preference not a "better or worse" kind of issue.





 

I don't have a red dot, but when I dial my Mk.4 CQ/T down to 1x, I get a lower 1/3 cowitness that isn't at all distracting.

I have an ACOG as well, but being permanently magnified, there is no cowitness.

YMMV.

I prefer the fixed FSB since it is pinned to the barrel and considered part of the barrel, the flip up sight bases tend to be the clamp type attaching with set screws, if you hit your front sight during a move and shoot scenario there is the potential to move the FSB and cut off the gas port, making the rifle a single shot as it will no longer cycle.

Cowitnessed RDS I find are really fast to get on target and having the dot cowitnessed with the irons I can transition back and forth between optic or irons with ease.

I had a red dot sight mounted on a flat top with a fsb.  I discovered that the red dot had to be mounted higher than I found comfortable to be even get the dot over the fsb post.  Got rid of the red dot and went with an A2 upper and made it a fun gun.

On another AR, I noticed a slight blur (fsb, just enough to be annoying) in the bottom of a Bushnell Elite 1-4 scope.  Put a clamp on gas block on it since it's my coyote gun.

I'm going through this same dilemma and when I asked it seems people are split, some say keep the FSB and some say go with a longer free float rail. I honestly haven't made up my mind.  The Optics forum has some good examples of what cowhitness, 1/3 cowhitness and no cowhitness look like.

I have gone both ways... but have returned to the FSB. It's robust and since I run Aimpurnts in LaRue LT150 mounts with a LT103 BUIS, it gives me a quick backup if the dot ever goes down...

- Clint

I have both and I prefer the fixed FSB for what I feel is more dependable, stronger and for me faster with a RDS...

I also prefer absolute co-witness so that may have something to do with it...

Really it comes down to what you prefer.  If your running a magnified optic then I would say lo-pro gas block but if your just using a RDS then I vote to keep the FSB.  Plus it makes it slightly cheaper to not have to buy a front flip-up sight.

FSB all the way for me. More robust, always ready, very little to break or malfunction. They only compliment a red dot, and they are basically invisible on magnification.
YMMV

My Stag was set up with removable front and rear sights. That configuration gave me the option of removing the iron sights and mounting a scope (which is how I have kept it), using iron sights only, or going with my EOTech and flip up irons. I use the Stag with a medium variable power scope for coyote hunting. I like the flexibility of the flat top.

Several years ago there was an article written by Larry Vickers and he addressed this as well as flash hiders.

He pretty much stated that people  in his view that showed up with the flip sights on a clamp on FSB had range toys, people with fixed FSB which is considered a part of the barrel had serious guns.

I tend to agree with him on this.

I was in the same dilemma and went with the FSB... couldn't be happier! I think it looks much more attractive and I've never had it get in the way.

Having used both I personaly would recomend a FSB. It is simple and bombproof. A lot of people would tell you to go with the longest FF rail you can and throw on a BUIS, but a lot of those people run an optic and rarely actually use their irons. Hence the term "back up iron sight".

It's personal preference, you might want to try it both ways to find out what you like better.

My preference with SHTF type AR are fixed FSB, I've got it on all my current 6 carbines and rifle.

The only exception would be a precision rig that I'm building now, it will mainly use optics and it will have a flip up BUIS set.

For me... it's quite simple... The gas block is the heart of your AR. If it gets misaligned... for any reason, you now have a single shot..

I don't care if it's got a clamp, or a set screw.. if it takes a good hit, and  becomes misaligned... your screwed.Metal heats up and expands ans contracts... causing movement.

A pinned  gas block is not moving... it's a solid part of the barrel..

And a FSB is always up... easy to use with your red dot as a big ghost ring.. even if the dot is off...

And it allows for a quick zero check...


I don't own "range toys"  I need and want them ALL to work... anytime... so they all get pinned FSB's

You do what you want.

I prefer the fixed post with a lower third for my Aimpoint.  If your dot goes down there's no need to flip anything, just slightly adjust your hold.  I run fixed front and rear(DD fixed rear).

Fixed FSB for me,always ready and more robust.

I appreciate all the responses.  I think I'll go with the FSB and go from there.  

This has been a good thread.. I've never really thought about the merits of either/or.. I like the looks of no FSP, but if it works better, that's good enough reason to keep it. ;) Both my AR's have are fixed FSP.. I guess I'll leave it that way.. :)

It all boils down to personal preference and its something you gotta try....your preference may change during the course of long term use in a variety
of shooting situations...

You might find that you are faster and more accurate with one form over the other...

It's not really a matter of  "which will be better" it's more a matter of "which will you be better with"....

-imo

I am ordering my second GG&G pinned folding front sight / gas block.
My first optics platform, a 14.5" Bushmaster will be the recipient. Holosight only with a possiblity of changing out to a A-1 carry handle / A-2 apperature assembly.  The pinned gas block / sight is strong as hell and with the sight folded I retain the sight picture I have with the currently hacked off sight tower. GG&G knows how to install these for sure.

If you want a FSB and a longer rail on a carbine system, go with a DD RIS II rail with FSB cut out. It is the best of both worlds, and I really like mine. Pus a great pace to mount a Surefire X300 light.

I have both.  I'm reading a lot above that says that the fsb is "bomb proof" / sturdier.  I won't disagree.  However, my last two rifles are Recce style with 12" rails covering low profile gas blocks, and I've been pleased.  There is no con to the fsb to me other than I do not want it in my sight picture (unmagnified Eotech / Aimpoint).  

Has anyone actually had a Recce configuration gas block (pinned or not) fail?

the way I look at it is very simple.
if i buy a barrel with a fixed fsb, i can remove it,replace it with a clamp on, and still have it to go back to.
if  i buy a gas block, i have to spend over $100 to instal a fsb, and HOPE its right.
buying it with a fixed fsb gives some options.
to sum up, its easier to take it off, then put it on.

That doesn't even make any sense.  You can easily operate a red dot independently of your front sight post.  That's sort of the point.  If you've mounted the RDS properly, and are shooting both eyes open, I never notice my FSB.  

And swapping out a tritium front sight post is one of the easiest things to change out on the rifle.  unscrew the A2 post.  put the tritium post back in it's place.

Railed gas blocks are hardly ever pinned, and most often a lower height than the flat top receiver so you have to buy a special front sight that's taller for it, or buy a riser which even further limits your choice of front sights as many sights don't fit on the riser itself.  

I've found that there's no good reason to remove or assemble sans fixed front sight base.  You mentioned "a little self defense" as one of the reasons for the rifle in the OP, so I think you would be crazy to use any other gas block for a "serious biz" rifle like that.

I'm interested in the idea of a clamp on sight bending, knocked askew, or failing in any way that's related to it's attachment method.
Outside of theory, who has seen a clamp on fail? Especially when clamped on correctly.

I have many items in my life that use a clamp on design that I literally put my life on the line when using. I'm sure a car mechanic can think of dozens. In the bicycle world a handle bar that slips in the stem could easily result in me eating thru a tube for life. Crapping in a bag, rolling in a chair.
Heck, even the wheels are clamped on.
The front sight uses similar mounts as my road/mtn bike stems, which never fail, slip, or given me anything other than perfect usage. I'm guessing that what it takes to make that handle bar actually move while riding might involve collisions that will poorly affect the rest of my day.

From my limited understanding of clamping forces, they aren't to be underestimated.

Perhaps the same w/ a gun, if it's going to knock a clamped sight askew, likely the gun won't be in my hands anymore. Plus then I'd have to wrest it free from the combine that ate my gun.

Now.. the likely event of a amateur gun smith (me) screwing up the install of a clamp so that it's ready to fail (not tight, too tight, whatever else I forget), that I can see.

And as for the co-witness? I like the view of a dot w/o iron sights visible. I'm not saying it's night and day, but it's clearer w/o a rear/front iron post in the way.

I stand corrected on the tritium front sight post, I honestly did not know that they made these.



As for the co-witness, I was just trying to point out that SOME people prefer to have nothing cluttering up the sight picture, and those people will often prefer a folding BUIS set in conjunction with an optic.



I'm confused why you said it doesn't make sense.  You do realize that this is personal preference and some people DO prefer to have no irons in their sight picture through their non magnified optics...yes?



If you understand that some people have that preference, then it should make sense why I listed it as a con for THOSE people.
 

I only have one AR that doesn't have a regular FSB, and its a Noveske Afghan barrel.  It has a low profile gas block that is pinned in place and has a set screw on the bottom.  I think it's every bit as solid as a regular FSB.

If my optic fails I want the transition to irons to be seamless.  Having to flip up my irons doesn't = seamless.  Just my $0.02.

There is no need to line up the dot with the post. If your doing it this way your missing the whole point of the RDS. Leave both eyes open and simply superimpose the dot on the target, the front and rear sight don't even come into play.



 

I leave my Troy front sight flipped up so it is already there if my RDS fails (unlikely, it is an Aimpoint ).  I do like a folding rear sight out of the way as I can shoot with just the front sight and the optic tube in a pinch until I get a second to flip up the rear.

My 2nd AR has a FSB, which really has no downsides either, it isn't really noticeable when using a RDS correctly and doesn't interfere with magnified optics either.

OP: as to the two options you posted, the FSB for sure.  Railed gas blocks have some serious downsides.  The height isn't standard making it hard to find sights that work and you aren't even gaining any rail space.  I could see going with a long rail over a low profile gas block, which is how folding front sights usually come into the picture anyway.  A carbine length handguard and a raild gas block just strikes me as