In terms of durability a FSB is unbeatable. As far as rail-flex shifting point-of-aim a FSB cutout rail is the best set up. Why don’t we see more FSB cutout rails?
I would like to see a free float 15" mid-length FSB cutout rail in keymod or m-lok. Both a two piece version for use with a standard barrel nut like the Centurion C4 and a one piece version with a bomb proof barrel nut lock up.
The Troy Delta Battle Rail Mid sort of fits the bill but the mounting method leaves a lot to be desired.
From what I’ve learned I don’t think there’s enough of a benefit to bother. Also with the FSB you loose sight radius vs mounting on the end of the hand guard.
Both of those really more address the question of fixed front sight post or no. There are almost as many people out there that like the FSP more than folding setups, and a lot of those are more diehard. mark’s recent thread comes to mind. As for the actual question, I was wondering this myself recently. DD and Centurion are the only two that I’d consider but I don’t see Centurion’s real on their site anymore. I’d be all about a KMR cutout.
If the current offerings put ~2" of rail in front of the FSP, how much rail would be added with a 15" rail? My guess is ~4-5". What are you going to mount there that you need all that rail? You could put a surefire X300 there but then you either put it against the FSP and don’t use the extra rail or you mount it out further, create an awkward gap and have to reach further for the switch. Unless you can scratch your knees while standing up straight, this last part would most likely be an issue.
The only problem that I have with the front sight block is how hot it gets, and how it’s located right where I want to grab the rifle on FSP rails.
If it was properly blocked from contact, I would be happier.
I think the most probable answer is the growth in popularity of DIY Ar15s, most folks can handle wrenches and pins and screws, but I don’t think many are set up with drill presses. It took me quite some time to find a local gun smith that actually could do it, most in my area did not offer the service.
Conversely, those that buy a pre-built AR with the FSB are less likely to add a quad rail, and of those that do I don’t think many will opt for the more difficult install vs a drop it quad replacement.
I’d love a FSB cut-out KMR rail. It would be awesome on a 6920. I just don’t see them selling that many. Currently, I have an Omega X 12.0 and don’t care for the profile compared to a RIS II, but can’t bring myself to swap for a RIS II.
This is exactly my predicament. I love my 6920, but the short hand guard is so annoying. Removing the fsb and replacing it with a flip sight just seems like sacrilege to me. And I just do not like quad rails. A KMR carbine cut out would be amazing. If M-lok is cheaper to produce, we may see something along those lines in the future?
Well if you buy the gun assembled and want something different than we cut the sight off, this gives you more options on the rail.
I would say most of the “die hards” would be more into the forged pinned gas block, this is achieved but the cutting down of the fsb. Companies are going to make what sells, and long flat rails with flip up sights are cool so that‘s what sells. Also consider the move to magnified optics, although functional the fsb can be annoying.
Also figure in the variety of gas systems, with a flat top you can fit on any, with the fsb cut you’re limited to carbine, the rail companies know this, it saves them money and time to produce one rail that will fit different gas systems
I have some shaved FSB guns too. I like that route for magnified optics, but for a red dot or irons I’d rather have them fixed and a rail around the FSB.
Overall, I like as plain, simple factory gun as possible for self defense.
That is a good point about heat, the FSB on a midlength is right where most people put their support hand on the rail, but having a 14"/15" midlength FSB cutout rail with about 2"-3" of space in front of the FSB would be perfect for a 12 o’clock light mount. I have short arms and run 15" NSRs with lights toward the end without issue.
Plenty of folks like fixed irons with lower 1/3rd non-magnified RDS, I am gravitating towards always running my sights up. With mild astigmatism, sights up make the dot appear smaller and sharp.
A 15" KMR with middy cutout would be awesome, though if it is a pain to install a FSB on a bare barrel I am sure pressing the pins behind a rail is a major PITA.
Two piece is the way to go. I was always waiting for Centurion to make a lighter, modular version of the C4 but it never came and now it seems cutout rails are diminishing.
Why is a drill press needed to install a free floated handguard? I reconfigure uppers with different free floated handguards all the time and I’ve never needed a drill press. If the handguard has a FSB cutout, it doesn’t change anything…if you can put one without a cutout on, then you most likely can put one with a cutout on.
I don’t think the lack of FSB cutout versions is due to anything other than most people wanting to use folding sights. The demand for handguards with the FSB cutout is probably minute compared to the rest, and companies are focused on making what will sell. I wish there were more choices regarding FSB cutout handguards…I really need one for my Kino upper and there’s not much to pick from.
