ok I'll ask... what's wrong with mounting your front sight on a rail? (no FSB)

[skyugo]

I kind of stumbled into a gun with a rail mounted front sight. I'm running MBUS (front and rear), with the front sight mounted on a 12" midwest industries free float rail. I expected some sort of fairly tangible accuracy issues. If anything I've been quite impressed with how good the accuracy is. I'm not a bench rest shooter, and I don't think anyone else here is either....

I do plan to upgrade to a set of DD fixed sights soon, for duability, and because i think fold down sights are silly with no optic. (goin into point shoot mode! click click)

So what's so bad about this kind of setup? A quality fixed sight on a rail isn't going to break off or come loose. The other side i guess is gas blocks... I'm currently running a spikes set screw block... not the best setup, but there should be no issue with a pinned cut down sight or a good clamp on block.

just looking for opinions...

[DeltaSierra]

Not sure if this will help or not, but it might be worth reading:


http://m4carbine.net/showthread.php?t=97461

[militarymoron]

nothing wrong with it unless you put enough pressure on the rail or barrel while taking a shot, such that the front sight is no longer aligned with the barrel.

[skyugo]

nothing wrong with it unless you put enough pressure on the rail or barrel while taking a shot, such that the front sight is no longer aligned with the barrel.

fair enough...
I guess i'm assuming the rail is perhaps more stiff than it really is.
I recall a guy asking what was so great about free float tubes, and it was again the same situation, applying pressure to standared handguards can flex the barrel. So i'm basically in a slightly better situation than someone without a free float tube. I'll take it.
I suppose in precision shooting it's worth noting that pressure on the handguard can change POA.

[Surf]

Purpose of the rifle is a big consideration. I run rail mounted sights on a few of my for fun rifles but unless if it is a scoped SPR type all of my working rifles will have a fixed and pinned front sight base. Back up irons are fixed again unless in an SPR type set up.

As MM mentions the issues of the rail mounted sights may come more into play when you start getting deflection on the rail which can cause a pretty good misalignment of the irons which is of course more noticeable as distance increases. Most don't test or even notice this because quite frankly many don't shoot enough in that configuration with just irons. Another thing to consider is that the weak link in the sight attachment may not be between the rail and the sight, but the issue might come between the connection of the rail and the weapon itself. I have seen enough rails move just enough from hard use to make it a concern. Same concept as to why many will suggest not bridging the gap between the upper and rail with an optic set up.

[An Undocumented Worker]

If you use a shooting sling you can most definately induce enough flex to noticeably throw off the poi even at modest ranges, though realistically you would only use a tight sling at longer ranges which will make the pressure induced sight misalignment even more noticeable.

[fixit69]

Purpose of the rifle is a big consideration. I run rail mounted sights on a few of my for fun rifles but unless if it is a scoped SPR type all of my working rifles will have a fixed and pinned front sight base. Back up irons are fixed again unless in an SPR type set up.

As MM mentions the issues of the rail mounted sights may come more into play when you start getting deflection on the rail which can cause a pretty good misalignment of the irons which is of course more noticeable as distance increases. Most don't test or even notice this because quite frankly many don't shoot enough in that configuration with just irons. Another thing to consider is that the weak link in the sight attachment may not be between the rail and the sight, but the issue might come between the connection of the rail and the weapon itself. I have seen enough rails move just enough from hard use to make it a concern. Same concept as to why many will suggest not bridging the gap between the upper and rail with an optic set up.

THIS and..

The two I have left have flip up. Have had no front sight issues...

That said, I was going to shoot today, and the right side of my Troy rear sight ear was bent. I forgot to flip it down last time I shot. My bad, yes. But it makes me wonder now...

[Failure2Stop]

If it swivels, folds, screws, levers, or detaches it will have more potential failure points than one that is properly taper pinned to the barrel.

[Belmont31R]

If you are using them as a BUIS (BACK UP) then you should not be concerned. With most modern quality main sights (RDS, 1-4x, high power variable) it would take a lot of damage or other failure to relegate yourself to the BUIS.



Anyways, no matter if if you have a pinned FSB like the typical A-frame or a rail mounted flip up they are subject to flex. The same holds true to nearly any firearm.

[skyugo]

I do all of my shooting inside of 200 yards. 16" middy with a gov profile barrel.

I want to put a 12 o clock mounted x300 or TLR1 ahead of the front sight. that's part of the reason i picked up the long railed upper.

The concern i'd have with something like a daniel defense rail where the front sight block remains is heat around the light... those sights get toasty fast. If you're trying to operate a light around that it could be hazardous.

Optics are somewhere in the distant future for me, probably a basic aimpoint.