View Full Version : Sig Sauer M400 Ar Help?
Delmonte67
10-08-12, 13:04
My brother Just bought a Sig Sauer M400 AR15, he wants to put a Reddot on it and he was wondering if the front sight post would get in the way-can it be removed easily? And what are his options as far as a new picitinny railed forend replacement for this weapon? I searched the net but cant find a difinitive answer, any info would help! Thanks fellas! D.
Leave the FSB as is. You can get mounts for absolute or lower 1/3 co witness for the RDS.
It can be removed like any other AR on the market. It is no different. Removing it is unnecessary for use with a red dot but possible with a low profile gas block.
It's his gun, but the front sight being in the way isn't a problem as long as he aims the red dot sight with both eyes open. He will only see a slight shadow of the front sight IF he see's anything at all.
He can also purchase raisers for his red dot that place the iron sights in the lower third of the red dot tube or window.
edit -
sorry didn't see the thread had replies.
It appears that he has a Carbine Length Gas System so if he goes with a rail system handguard and decides to keep the front sight as it is, he will need a 7" rail system or extended rail with front sight cutout.
If he's not interested in free floating the barrel, the Daniel Defense EZ Carbine would be a good option.
https://danieldefense.com/rail-systems/ez-cartm-7-0-carbine.html
For the ease of installing and he was looking to free float while keeping the front sight in tact, I'd look at the Centurion Arms C4 FSB
http://www.centurionarms.net/index.php?option=com_virtuemart&page=shop.product_details&flypage=C4-FSP-rails.tpl&product_id=82
Delmonte67
10-08-12, 13:32
Thanks, I suggested a riser if needed, he was leaning towards taking the front sight off (anyone know how to remove this if he goes this route- without scarring up the barrel?) He definitly wants a different forend with Pic rail for accessories. Any suggestions on a good forend? Will any Ar forend go on his gun? I'm not familiar with this Sig, seems like a nice first Ar though, Thanks again.
Thanks, I suggested a riser if needed, he was leaning towards taking the front sight off (anyone know how to remove this if he goes this route?) He definitly wants a different forend with Pic rail for accessories. Any suggestions on a good forend? Will any Ar forend go on his gun? I'm not familiar with this Sig, seems like a nice first Ar though, Thanks again.
Both you and your brother should do a lot more reading before you spend any money or take any tools to that rifle.
Delmonte67
10-08-12, 14:04
Its kinda why I posted this, suggestions and feedback is what would help.
DeltaSierra
10-08-12, 14:09
Its kinda why I posted this, suggestions and feedback is what would help.
Read the stickies.
Then, if those stickies haven't answered your questions, use the search function.... If that doesn't answer your questions, feel free to ask...
The issue here is that you are asking questions that you could have answered yourself if you had searched to site, or read the stickies.....
Talking off the front sight is not really a big deal as long as you have the proper tools to do so AND you do not have a 14.5" barrel with pinned and welded muzzle device.
I'm sure a search of this forum or on google would provide results of how to do so.
The two rails I provided links for are well built and easily installed by the user.
Its kinda why I posted this, suggestions and feedback is what would help.
There is a ton of great information here at M4C. There is nothing that you are asking that hasn't been asked and answered here before. There are multiple threads covering shaving the FSB, selecting a RDS and the merits of each one, mounts and risers, handguards, etc. There are stickies, charts, etc. here that break down manufacturers and models by all kinds of attributes and metrics. Taking the time to read through all of that will give you and your brother a greater breadth of knowledge and help you ask better, more narrowly defined questions that will be significantly easier to answer and give you much better answers to your questions.
Delmonte67
10-08-12, 14:42
There is a ton of great information here at M4C. There is nothing that you are asking that hasn't been asked and answered here before. There are multiple threads covering shaving the FSB, selecting a RDS and the merits of each one, mounts and risers, handguards, etc. There are stickies, charts, etc. here that break down manufacturers and models by all kinds of attributes and metrics. Taking the time to read through all of that will give you and your brother a greater breadth of knowledge and help you ask better, more narrowly defined questions that will be significantly easier to answer and give you much better answers to your questions.
I totally understand the repetative questions asked continually, I did use the search engine with not a lot of an answer, Ill check those stickies, and try the search engine again. Thanks for the nudge in the right direction, last thing I want to do is help screw up my brothers new gun. Just trying to learn D.
Delmonte67
10-08-12, 15:13
It's his gun, but the front sight being in the way isn't a problem as long as he aims the red dot sight with both eyes open. He will only see a slight shadow of the front sight IF he see's anything at all.
He can also purchase raisers for his red dot that place the iron sights in the lower third of the red dot tube or window.
edit -
sorry didn't see the thread had replies.
It appears that he has a Carbine Length Gas System so if he goes with a rail system handguard and decides to keep the front sight as it is, he will need a 7" rail system or extended rail with front sight cutout.
If he's not interested in free floating the barrel, the Daniel Defense EZ Carbine would be a good option.
https://danieldefense.com/rail-systems/ez-cartm-7-0-carbine.html
For the ease of installing and he was looking to free float while keeping the front sight in tact, I'd look at the Centurion Arms C4 FSB
http://www.centurionarms.net/index.php?option=com_virtuemart&page=shop.product_details&flypage=C4-FSP-rails.tpl&product_id=82
Thanks bro! That Daniel defence rail is just what he wants, I just forwarded the link to him and he was really interested.
If neither of you know what you're doing I highly recommend you stay away from the FSB. Also you might want to make sure that anything that you do can be put back. There's absolutely no reason to cut down the FSB or remove it simply because you think that it's going to interfere the red dot. If you want to rail anyone use a front flip up sight that's understandable. But the red dot sight can easily be used in is used in conjunction with the front sight base all the time.
mkmckinley
10-08-12, 16:01
As others have said leave the FSB alone and just get a lower 1/3 mount for like an Aimpoint H-1. The pinned FSB is the best front sight you can get. It's the most robust, it's attached to the barrel so it holds it's zero better than rail mounted sights, it's always up which many consider the best configuration for a FSB, and most importantly you already have it so it's free. If you mount a RDS and actually go shoot the carbine I guarantee you won't even notice it. You only notice it when you dick around with the weapon while you watch football in your underwear. A pinned FSB like the one your brother has is a desirable feature and many people look for carbines with just that.
I keep the guns locked up when watching football. I'm an Eagles fan. :D BOT sage advice here, those picatinny gas blocks are a step backwards IMHO.
Delmonte67
10-08-12, 17:13
[QUOTE=mkmckinley;1412836]As others have said leave the FSB alone and just get a lower 1/3 mount for like an Aimpoint H-1. The pinned FSB is the best front sight you can get. It's the most robust, it's attached to the barrel so it holds it's zero better than rail mounted sights, it's always up which many consider the best configuration for a FSB, and most importantly you already have it so it's free. If you mount a RDS and actually go shoot the carbine I guarantee you won't even notice it. You only notice it when you dick around with the weapon while you watch football in your underwear. A pinned FSB like the one your brother has is a desirable feature and many people look for carbines with just that.
I talked to him earlier and explained that a Reddot should co- witness just fine without removing the FSB. He thought it was an easy on/off mod, he said he wont mess with it. He still definitley wants a quad rail forend for sure. Oh and um by the way- my wife only lets me watch "Sons of guns" in my underwear not football- cause sometimes the in laws come over on Sunday and I'm in charge of the grill-she doesn't want me to overcook my Italian sausage! :DThanks for all the info fellas! D.
If you want a full size rail, check out the troy Battle Rail Charlie (http://troyind.com/%20/rail-systemsaccessories/rails/ar15m16-rails/drop-in-rails/troy-battlerail-charlie) and Delta (http://troyind.com/%20/rail-systemsaccessories/rails/ar15m16-rails/drop-in-rails/troy-battlerail-delta). They drop in and will provide a longer freefloat rail that will fit around a fixed front sight with no gunsmithing.
I'm pretty sure they will fit around the handguard cap, but I'd drop them a line to double check.
I just installed an Aimpoint Pro on my M400. The FSB does not interfere with the reddot and I left the original sights in place. Works great!
I have a M400 and taking the FSB off is no easy task for a beginner (myself included). It is press fit and the pins are ridiculously tight. I ended up using a Dremel w/ mettal cutting wheel at 30K rpm and VERY CAREFULLY cutting the FSB perpendicular to the barrel until it cut into the pins themselves. At that point, both pins had a fresh gorge running their entire length and I was able to tap the pins out. After that it was just a matter of removing muzzle device, removing the FSB, removing the barrel, removing the delta ring (lots of people just cut them off), installing a DD low-profile gas block, re-installing the barrel and then mounting a Troy Alpha rail. I was brand new to anything of this nature so I read a lot online and purchased a ton of armorer's tools in order to do that job right.
Recommended items (at least for me):
-Punch set
-Dremel
-Metal cutting wheels
-Receiver vice block
-Barrel nut wrench
-Wrench for muzzle device (if necessary) - one came as part of the barrel nut tool on my setup.
-Red loctite (if you are going to use a clamp-on lo-pro GB)
-Moly grease for the barrel nut
-Torque wrench
-Brass drift (for massaging the Sig FSB off the barrel)
-Lubricant (to keep the barrel from getting scratched up while removing the FSB.
It's not rocket science. Just study up, equip yourself with the correct tool and go to town!
Here are the results:
https://lh5.googleusercontent.com/-TUnFshpBH_o/UGJxRDCiO9I/AAAAAAAAd3I/mM0ix6Bv3i0/s1753/20120925_223556.jpg
I have a M400 and taking the FSB off is no easy task for a beginner (myself included). It is press fit and the pins are ridiculously tight. I ended up using a Dremel w/ mettal cutting wheel at 30K rpm and VERY CAREFULLY cutting the FSB perpendicular to the barrel until it cut into the pins themselves. At that point, both pins had a fresh gorge running their entire length and I was able to tap the pins out. After that it was just a matter of removing muzzle device, removing the FSB, removing the barrel, removing the delta ring (lots of people just cut them off), installing a DD low-profile gas block, re-installing the barrel and then mounting a Troy Alpha rail. I was brand new to anything of this nature so I read a lot online and purchased a ton of armorer's tools in order to do that job right.
Recommended items (at least for me):
-Punch set
-Dremel
-Metal cutting wheels
-Receiver vice block
-Barrel nut wrench
-Wrench for muzzle device (if necessary) - one came as part of the barrel nut tool on my setup.
-Red loctite (if you are going to use a clamp-on lo-pro GB)
-Moly grease for the barrel nut
-Torque wrench
-Brass drift (for massaging the Sig FSB off the barrel)
-Lubricant (to keep the barrel from getting scratched up while removing the FSB.
It's not rocket science. Just study up, equip yourself with the correct tool and go to town!
Here are the results:
https://lh5.googleusercontent.com/-TUnFshpBH_o/UGJxRDCiO9I/AAAAAAAAd3I/mM0ix6Bv3i0/s1753/20120925_223556.jpg
So instead of shaving tbe fsb down you destroyed it and installed a low profile gas block that is nowhere near as fail proof? Doesn't the troy alpha rail use the standard barrel nut? It sounds to me like you made your rifle less reliable. You would have been better off by cutting the delta ring off like "lots of people" and shaving down the fsb.
So instead of shaving tbe fsb down you destroyed it and installed a low profile gas block that is nowhere near as fail proof? Doesn't the troy alpha rail use the standard barrel nut? It sounds to me like you made your rifle less reliable.
I couldn't shave it b/c I had the SRP model. Way too much mass to deal with. Heavy too! I'm sure that some out there could have made it work but I chose the lo-pro GB route. Tons of people use clamp-on blocks and they come installed on many high-end offerings.
As for the Troy Alpha, it does use the standard barrel nut.
I hear ya though... Sig did not want that GB to come off...EVER!!!
https://lh3.googleusercontent.com/-XOcPEYXi8ss/UHZP-VgfG5I/AAAAAAAAeg4/2OHwfqQGMFM/s1600/20121011_004432.jpg
Railed GB weighs in a 1/2 lb (when it is complete). This pic does not show the cut off bayonet lug and sling swivel lug.
https://lh3.googleusercontent.com/-oJCjFZ2DbPA/UHZQXTVzFDI/AAAAAAAAehg/kBFgsUPl28k/s1600/20121011_004453.jpg
Check out how deformed the rail is. I had to beat on it for about 10 minutes after having it soak in PB Blaster for half an hour.
https://lh4.googleusercontent.com/-CBVfSIQrDz4/UHZTqL6lMHI/AAAAAAAAelY/LJ92ffVA9_A/s1600/20121011_005351.jpg
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