Fixed FSB in 2015 - Why?

I have been wondering for a little while about fixed front sight bases. I was issued a rifle/carbine with one throughout my military career, and most issued LE rifles/carbines I've seen also have fixed FSB's. 

 

I don't know why, but I just don't like them. It seems most companies are still selling a majority of AR-15 style uppers with fixed FSB's. I mean, try buying a BCM upper with no rail/handguard and a low-pro gas block... you can't.

 

I bet a majority of us desirous of free floating handguards immediately swap those FSB's out for a low pro block, which is sorta a pain in the ass.

 

Am I missing some awesome benefit of the fixed FSB? It's an unnecessary snag hazard, gets in the field of view of most optics (whether that bothers you or not is a different story), and limits rail options when a low-pro gas block does not. 

 

With modern optics and their reliability regaling BUIS to almost an afterthought for some of us, it seems like the need for a front sight always in our face would be even less. I've never felt unprepared even with my cheapo plastic Magpul flip up BUIS. If I was really worried about it, I'd buy nicer, metal ones and really not feel unprepared. 

 

Not really trying to start an argument, just wondering what's up with people's thoughts on the subject. 

 

 

 

 

Joined:      14 January 2010                Location:     Lobster emoticonMAINELobster emoticon

Original Post

I guess, like you said, it all kind of depends on how strongly you value the BUIS, in this age of modern combat optics.

 

I personally prefer standard front sight bases, especially on guns where I want a 24/7 back up front sight deployed.

 

Obviously, for Recce or SPR type guns, with magnified optics, then a rail mounted, flip down or offset front sight clearly makes more sense.

 

While I don't know this for an absolute, quantifiable, fact, I strongly believe that standard front sight bases are more mechanically accurate than rail mounted front sights, since standard front sight bases move in conjunction with their barrels as they flex.

 

Due to their taper pins mounting to the barrels, I also feel that standard front sight bases are the most securely mounted gas blocks available.  So much so, that I prefer to cut down a standard front sight base, rather than to use a set screw mounted low profile gas block, for use beneath an extended free float hand guard.

 

Also, they are far less likely to loose zero or become damaged, when compared to folding, rail mounted sights.

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Joined: 3/20/05 4:14 PM        Location:  North Carolina

I put a Troy rail on a 20" gun I built up.  Long handguard, gas block only, folding front sight on the handguard.  Couldn't get it zeroed.  Not even close.  That rail was off just a smidge and it wouldn't work.  So I put the fixed FSB back on.  I have another rifle with a folding FSB/gasblock.  I'll admit, I'm always a bit wary on whether the pic rail on top is truly in line with the bore, and that isn't a real concern when the front sight is mounted on the barrel.

-------------------------

Mark

Swear allegiance to the flag Whatever flag they offer

Never hint at what you really feel

Teach the children quietly For some day sons and daughters

Will rise up and fight while we stood still

 

Joined:  2/24/2003                          Location:  Nevada, USA

I'm with 4track for my go-to gun.  I'm still rocking a CompM2 and the FSB really doesn't hinder that at all.  Also, all my real-world experience comes from the military so I guess I'm just used to them.  I agree they seem more durable, are always ready, and at least in my experience more accurate than the BUIS I've used.

 

However, on my SPR-type rifle, I have folding BUIS front and back.

"These are the rules. Everybody fights, nobody quits. If you don't do your job I'll kill you myself."

 

Joined: 04/01/2004     Location:  Twin Cities, MN

This goes for both fixed front sights as well as running folding front sights up, but they do allow you to see any cant in the rifle that's difficult to see with the front sight down.  At moderate distance, it doesn't take much cant (rotation) in the rifle to start throwing rounds where you don't expect them.  Without some point of reference, it's very east to get the gun rotated all out of whack and not realize it.

I prefer a fixed front on a defensive gun.

 

One of the things I have my guys do when we train is a cold, unannounced qual or unannounced course of fire.  They leave their rifle in the rack in the car, and merely remove the mag of Gold Dots and insert a mag of 55 FMJ practice ammo. 

 

What I see is, regardless, is dead or weak batteries, even with Aimpoints.  Guess what?  No mulligan in those cases, they have to drive on and solve the problem at hand with irons. 

 

I consider myself more diligent than most people, yet I've sometimes checked my Aimpoint and found the dot brightness weak, and turning it up to max didn't make it much better, so of course the battery was on its last legs  (I never turn them off), and didn't have time at that particular moment to change a battery.

 

While a AP battery will last a very long time when the brightness is on a moderate level, leaving it on the highest setting will deplete the battery much quicker.  Sometimes people leave it on HIGH inadvertently, and either an extended period of this, or several shorter ones, means you're gonna have to change the battery sooner than anticipated.

 

In case of a murphy moment, I can at least use the fixed front and the tube of the optic as a large rear aperture, until I can erect the rear BUIS.

 

YMMV

 

Fixed front sight base or flip-up, I think it depends upon how the rifle is set up and application.  If running a magnified optic, I find that flip-up front & rear sights works better, as they allow a cleaner field of view.  On my SWAT rifle, I run a Aimpoint M3 on Larue mount, combined with fixed front sight base and Meprolight tritium front sight post, and Larue BUIS rear sight with XS same plane sight aperture.  I prefer this set up for all around SWAT work, as the fixed iron sight picture is in the bottom third of the field of view, and if the optic isn't working or didn't get turned on for some reason, all I have to do is tuck the chin down a little tighter and I am looking through the iron sights 

 

The rifle I take on the road is a SLR15 Commander, which has a 16" long sight fixed front sight base barrel, Meprolight tritium front sight post, C7 A1 type offer receiver with XS same plane rear sight aperture, and a Trijicon TA01 ACOG on top.  By having the ACOG mounted on top of the A1 fixed carry handle, I am able to go heads up to look through the ACOG, but also tuck the chin down tight and I am looking through the iron sights.   If I were to mount the ACOG on top of a flat top upper receiver, then the iron sights wouldn't integrate well due to the blocked field of view.  

 

I also have several rifles that are built on C7 A1 uppers, with 16"-20" barrels that have fixed front sight bases.  These rifles are strictly set up with iron sights and no optics.  These rifles use Meprolight tritium front sight posts, and XS same plane rear apertures. They shoot well, and the iron sights work if I do my part.

 

I do like optics, especially quality ones that are mounted correctly.  I find that optics generally allow most shooters to have more consistency in their hits, and most shooters are quicker to get hits on target when measure on a shot timer.  I see a lot of our LEO's at work that use optics as a crutch, as many can't shoot iron sights very well, and rely on their optics to carry them through, so how will they perform when their optic has issues or doesn't run due to Lil Murphy the Leprechaun screwing up things during a gunfight and they now have to rely on their irons?  My opinion is to master the irons, then add an optic, as I see good iron sight shooters that are usually hell on wheels with an optic.  

       

CY6

Greg Sullivan "Sully"
SLR15 Rifles
TheDefensiveEdge.com

(763) 712-0123

Originally Posted by Sinister:

One of the very few things I buy from ARMS (the exception that proves the rule I suppose) is their folding front sight.  Fewer screws and more grab than the Yankee Hill folder, and if you really have to you can drill and drift pin it.

 

 

 

 

We have built rifles using this front sight base, I prefer to pin them.  I like it, it is a quality product and is extremely tough.  Here is a SWAT Magazine article that shows some pics on our Excalibur model http://www.slr15rifles.com/v/vspfiles/assets/images/excaliburswordinstoneswatfeb2012.pdf 

 

CY6

Greg Sullivan "Sully"
SLR15 Rifles
TheDefensiveEdge.com

(763) 712-0123

Originally Posted by fixit69:
Here is something I never gave much thought to. When everyone says to go with a free float hand guard, does the added weight of the fixed sight a plus or a minus for accuracy compared to a lo-pro? Anyone broke that down yet?

I thought the whole point of a free float rail was to limit the rail screwing with barrel harmonics, so what does the weight of the front sight have to do with this?

Hippies are just free range yuppies. - M. Wilson
Originally Posted by Andrew Yersin:

       
Originally Posted by fixit69:
Here is something I never gave much thought to. When everyone says to go with a free float hand guard, does the added weight of the fixed sight a plus or a minus for accuracy compared to a lo-pro? Anyone broke that down yet?

I thought the whole point of a free float rail was to limit the rail screwing with barrel harmonics, so what does the weight of the front sight have to do with this?


       


Thinking out loud. More weight equals more distortion.
Originally Posted by fixit69:
Originally Posted by Andrew Yersin:

       
Originally Posted by fixit69:
Here is something I never gave much thought to. When everyone says to go with a free float hand guard, does the added weight of the fixed sight a plus or a minus for accuracy compared to a lo-pro? Anyone broke that down yet?

I thought the whole point of a free float rail was to limit the rail screwing with barrel harmonics, so what does the weight of the front sight have to do with this?


       


Thinking out loud. More weight equals more distortion.

Now i see what you mean, I thought you meant A fixed front sight on the rail vs a low pro folding sight on the rail. Duh, sorry

Hippies are just free range yuppies. - M. Wilson

I'm looking at a midlength BCM upper with a FSB and a KMR rail.  Rail doesn't touch the FSB at all so how would it be different than a lo-pro block (other than ounces)?  Maybe I misunderstood you.

"These are the rules. Everybody fights, nobody quits. If you don't do your job I'll kill you myself."

 

Joined: 04/01/2004     Location:  Twin Cities, MN

Originally Posted by Andrew Yersin:
Originally Posted by fixit69:
Here is something I never gave much thought to. When everyone says to go with a free float hand guard, does the added weight of the fixed sight a plus or a minus for accuracy compared to a lo-pro? Anyone broke that down yet?

I thought the whole point of a free float rail was to limit the rail screwing with barrel harmonics, so what does the weight of the front sight have to do with this?

A barrel has harmonics.  Things that are fixed to it alter the harmonic, but it is altered consistently.  So once you've zeroed the rifle, the zero doesn't change.  The reason for the free float handguard is so different pressures on the handguard don't affect the barrel.  Whether you are shooting from a rest, a sling, C-grip way out front, grabbing the mag well, up against a barricade, it doesn't matter.  The handguard won't affect the barrel.  It has nothing to do with the weight of the sight.

-------------------------

Mark

Swear allegiance to the flag Whatever flag they offer

Never hint at what you really feel

Teach the children quietly For some day sons and daughters

Will rise up and fight while we stood still

 

Joined:  2/24/2003                          Location:  Nevada, USA

I currently run a DRMO A1 as a patrol rifle at work with both the standard FSB/Carry handle and an old M68 CCO.  I'm very comfortable with this, and even when I set up my own gun with a free float hand guard I put a DD fixed rear sight and a DD FSB style rail mount front sight on my rifle.

 

I like redundancy, and I like being able to switch to my back ups with nothing more then just a slight adjustment of my head. Just personal preference, but I (by policy) always run an un-magnified optic so co-witnessing isn't an issue.

 

The one time I used my rifle for real I actually used both my M68 and my iron sights.  I wasn't sure I was scoring hits on the bad guy (apparently the movies lied to me) so I made a slight adjustment of my head, picked up my irons and Charlie miked.  Should we ever be allowed personal patrol rifles at work, it will be a BCM complete midlength with a fixed FSB, rail mounted fixed rear A2 sight or similar (just because it's what I'm used to) and the M68.

Originally Posted by LightScout:

       

I'm looking at a midlength BCM upper with a FSB and a KMR rail.  Rail doesn't touch the FSB at all so how would it be different than a lo-pro block (other than ounces)?  Maybe I misunderstood you.


       


I guess my thoughts were stemming from "wish I could buy an upper with most of the parts assembled, and put this shiny new awesome ALG handguard on it. But I can't.

It's sort of a moot point (and dumb of me) anyway because the gas block would have to come off during the barrel nut change. So I kinda get it now, at least from that facet.

I see various justifications for the fixed FSB and they all make sense. It just struck me as one of the last external design vestiges that seems to remain the same when we're swapping everything else out, and it limits options in ways low-pro gas blocks don't.

Good discussion, I feel close to you guys right now ;-)

 

 

 

 

Joined:      14 January 2010                Location:     Lobster emoticonMAINELobster emoticon

Originally Posted by Sinister:

One of the very few things I buy from ARMS (the exception that proves the rule I suppose) is their folding front sight.  Fewer screws and more grab than the Yankee Hill folder, and if you really have to you can drill and drift pin it.

 

 

I have been thinking of getting this for my next two builds.  My wife does not like the FSB and I like them some times. 

Could you use an extended Carbine Rail like the Centurion Arms with this? 

Originally Posted by SFF:

I prefer a fixed front on a defensive gun.

 

In case of a murphy moment, I can at least use the fixed front and the tube of the optic as a large rear aperture, until I can erect the rear BUIS.

^^^ THIS.

 

I run flip ups front and rear with a T-1 for my optic . . . but I'm a civilian.

 

If I was using this 24/7 on duty, the fixed front sight is the way to go mainly for the reason quoted above.  I experimented with the T-1 off and the front sight up and found I was very accurate out to 25 yards using the T-1 as a rear aperature.  With the front sight down, 7-10 yards was my limit.

Love, Loyalty, Life, Leadership

 

LOCATION:  The Sixth Borough (Miami)

 

EDC Pistol Training LLC

www.edcpt.com

I recently spec'ed out Patrol rifles to be assigned and issued to my 18 Canine handlers. I met with my counterpart who is my agencies Range Master. We decided that whatever is picked for the Canine unit will be what he replaces our current Patrol Rifles with, as they need replaced. 

 

The bottom line is money. At an agency cost, you can get a gun with a fixed front sight post much cheaper. If you were just buying a couple of guns, the cost difference is not as big of an issue. When you are looking at a couple of hundred guns, it defiantly is an issue. 

 

 

 

Joined: 4-23-04                                          Location: SW Ohio

For me, a fixed front sight post pinned on the barrel is the least complex most durable option. No worrying about a bent rail,or loose screws. Rails are great, and for some things there isn't a better mounting option, but they are added levels of complexity. Just like I won't mount a pic rail segment in a M-lok slot then add a light mount to that when there are direct mount options, I won't mount sights on the rail if I can mount them to the barrel or reciever.

About 2 months back I built out a truck gun.  Priorities were reliability and price in case it was stolen.  I wanted this gun to be a little more basic than some of the others I'd done over the last few years.  In the old BCM catalogue there were some pics of the old Magpul Duo.  I'm  by no means a fanboy but the rifle featured in some of the pics just appealed to me.  16" middie with MOE grip, stock, and forend.  I had an old TLR, an Aimpoint, and KAC micro rear BUIS to fill it out.  Its solid dependable and saved me the cost and loss exposure of a FF rail, sling mount, low pro gas block, folding front BUIS, rail panels, QD sling swivel, etc.  That all adds up fast.  The gun I built out is solid and still hits out 300 with boring reliability.  All that plus there is just some asthetic apeal in it after so long without one.  Like grabbing a revolver some times or using a paper road map just so you know you still can do it.

Not to be a dick, but a fixed FSB is harder for the lowest common denominator to break, lose or hock. 

___________________________________________________________________

I'm either dead right, or horribly wrong. Either way the results should be entertaining.

 

"Shoot the MOTHERF$%^ER until he changes shape or catches fire"  the PAT ROGERS

Okay, question, for a kids first AR, would you get a fixed front site and a carry handle?  Reason why I am asking is well I have a little dude and dudette on the way.  My wife hates the FSB with a passion, me, well its hard not for me to not want one.  Privates cant break Them so they should be kid proof.  

Originally Posted by Spacetaco:

Okay, question, for a kids first AR, would you get a fixed front site and a carry handle?  Reason why I am asking is well I have a little dude and dudette on the way.  My wife hates the FSB with a passion, me, well its hard not for me to not want one.  Privates cant break Them so they should be kid proof.  

Nothing is kid proof.  Also, I don't consider kids to be a lowest common denomintator, they are suprisingly smart and prone to follow their inherent curiosity.

I have a sneaking suspicion you are going to supervise the kids and aren't going to have them jumping out of planes.  I'm also wagering that your wife will be shooting the rifle before the little ones will.  I'd go rail so that she is happy, then bolt on a set of irons to teach the kids. 

Just my 2 cents.

 

___________________________________________________________________

I'm either dead right, or horribly wrong. Either way the results should be entertaining.

 

"Shoot the MOTHERF$%^ER until he changes shape or catches fire"  the PAT ROGERS

Originally Posted by Spacetaco:

Okay, question, for a kids first AR, would you get a fixed front site and a carry handle?  Reason why I am asking is well I have a little dude and dudette on the way.  My wife hates the FSB with a passion, me, well its hard not for me to not want one.  Privates cant break Them so they should be kid proof.  

Since their first AR should be an M&P15/22, and they are railed guns w/o a fixed FSB, I'd go with a rail.

 

All joking aside, durability of a fixed FSB is more related to a defensive/survival situation.  For all other circumstances, a folded sight on the rail is essentially indestructible as it is unobtrusive and doesn't present the leverage issues to an impact.  Unlikely that you can have a likely scenario where the folded FS could be damaged where a fixed FSB would not.  If it is up and gets damaged, replacing a rail mounted sight is cheaper and easier than replacing a standard FSB.  That is a long winded explanation as to why I don't think kids are a factor in going fixed or rail mounted sights.  My only practical reason (as opposed to simple personal choice) for the fixed FSB is a rail not being optically aligned with the upper receiver/bore.  I was one of the unlucky ones. 

-------------------------

Mark

Swear allegiance to the flag Whatever flag they offer

Never hint at what you really feel

Teach the children quietly For some day sons and daughters

Will rise up and fight while we stood still

 

Joined:  2/24/2003                          Location:  Nevada, USA

I despise, absolutely despise, FSB equipped M4s. Back when I was running a dog (read: small horse) I had to have him hooked up to me, as he never appreciated the idea of a "recall". The long line would inevitably get wrapped around the rifle when the dog would come off sign and go to hunting or when we would have to negotiate terrain. Many times before I could get the leash and rile separated, my enthusiastic four legged partner (read: Malinois) would get back on odor or find a path through whatever was blocking our forward progress, and off he would go. If I had failed to get that leash away from the gun before he took the slack out, up the rifle would come, and contact it would make... typically FSB first straight into my mug (I've got pics somewhere from one such event where it looks like I'm crying blood). 

 

Go forward a few years to when I got on the Horse Patrol Unit. Since I'm wired a little bit weird, I still insisted on dragging my M4 with me everywhere. Even while mounted. My more westernly partners found this amusing and not very "cowboy". Not that I care, but the supervisor wouldn't get me a scabbard for my blaster so I was forced to carry slung. Typically across my back. Again the FSB was no friend to me. It would hang and poke at every opportunity.

 

After HPU it was back to the line and patrol work. My station is more highway orientated right now, with checkpoints and traffic stops. We still have our fair share of brush work, but its not line work. Anyway, you are in and out of your rig many times a day checking layups and other sensors. The M4 goes with me when I get out of my rig and guess what, that fucking FSB still gets hung up on shit. I've gotten good at how I stow the rifle and 90% of the time its a smooth deployment. But there is always that other 10% and any delay when you need firearm up and ready is too long.

 

I know there are arguments for them, but I would take a solid free floated keymod handguard (read: 15" KMR) with a set of quality BUIS and a T1/T2 over anything else at this point. The FSB has a purpose, but that said I'm done with them unless I can't do anything about it. Work gun aside (and with any luck we can get that changed too), all my rifle builds are FSB free. Out of the half dozen builds (Thats not counting the uppers I've helped build for buddies), I've had zero problems. Granted half of them I used the original FSB, cut it down, and reinstalled. But the others are LP gas blocks.  Either way... Fuck those things.

Originally Posted by Spacetaco:

Okay, question, for a kids first AR, would you get a fixed front site and a carry handle?  Reason why I am asking is well I have a little dude and dudette on the way.  My wife hates the FSB with a passion, me, well its hard not for me to not want one.  Privates cant break Them so they should be kid proof.  

 

BLUF:

I would not start a kid out with iron sights on anything, or even have them as an option.

 

I started my boys on .22 rifle at age 8 and 5. Iron sights were a goat rope. A conventional low powered scope was not much better. When I installed a RDS on the rifle things instantly got better. After a year of that the boys went with me killing gophers. The RDS was limiting, and we tried a 2-7x conventional out. By that time the basics were down enough that finding the right eye relief and centering their eye behind the conventional scope were no longer insurmountable. 

 

I can't really picture a great need at this point for worrying about iron sights until we get out the WWII bolt rifles for them in a few years.

 

 

Originally Posted by LightScout:

       

I'm looking at a midlength BCM upper with a FSB and a KMR rail.  Rail doesn't touch the FSB at all so how would it be different than a lo-pro block (other than ounces)?  Maybe I misunderstood you.


       


I guess my thoughts were stemming from "wish I could buy an upper with most of the parts assembled, and put this shiny new awesome ALG handguard on it. But I can't.

It's sort of a moot point (and dumb of me) anyway because the gas block would have to come off during the barrel nut change. So I kinda get it now, at least from that facet.

I see various justifications for the fixed FSB and they all make sense. It just struck me as one of the last external design vestiges that seems to remain the same when we're swapping everything else out, and it limits options in ways low-pro gas blocks don't.

Good discussion, I feel close to you guys right now ;-)

It does?

If you have opposable thumbs, some eye pro, a hand file, hammer and punch set, and a few other easy to use basic tools the fixed FSB is about as permanent and obtrusive as paper mache. You can cut it down, radius the edges, remove the bayonet lug, smooth everything out, punch out the taper pins, remove the now low pro gasblock, take off the old barrel nut, install new barrel nut, replace now low pro gas block, re seat taper pins, paint, install new fore-end and  enjoy.

 

So easy my wife did hers...

 

Location: in SE Idaho, the birthplace of television. 

Originally Posted by Somebody:
 
I guess my thoughts were stemming from "wish I could buy an upper with most of the parts assembled, and put this shiny new awesome ALG handguard on it. But I can't.

It's sort of a moot point (and dumb of me) anyway because the gas block would have to come off during the barrel nut change. So I kinda get it now, at least from that facet.

I see various justifications for the fixed FSB and they all make sense. It just struck me as one of the last external design vestiges that seems to remain the same when we're swapping everything else out, and it limits options in ways low-pro gas blocks don't.
 
Colt sells that upper now, or maybe the complete rifle minus the handguards. Let me look up the SKU for it.

 

This is somewhat a rough guess, but from what I've seen, most FF handguards use a proprietary barrel nut.  Those that use the standard require removal of the Delta Ring (a couple of exceptions), so at a minimum, you either use a dremel to cut off the Delta Ring parts and cut the the FSB down, I see little advantage to a factory low profile gas block over a fixed FSB unless it comes with a handguard you like and you aren't going to change it.  I've done enough work on uppers and handguards that I made the investment awhile back for a receiver block, bench vise and torque wrench.  Once you've bought the tools, it doesn't really matter.

-------------------------

Mark

Swear allegiance to the flag Whatever flag they offer

Never hint at what you really feel

Teach the children quietly For some day sons and daughters

Will rise up and fight while we stood still

 

Joined:  2/24/2003                          Location:  Nevada, USA

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