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MFI SIG 556 Rear Diopter Sight & Rail with Choice of Front Sights or No Front Sight (SIG GRAY) LAST ONE & NEVER TO BE MADE EVER AGAIN.

Designed specifically to fit the SIG 556 & SIG 551A1 Series Rifles & Pistols.

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Was: $395.00
Sale: $365.00
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Save: $30.00


Even though I talk about the MFI Front Hooded SIG Swiss Style Sight... They are NOT actually available yet.

Here is the situation: The Hooded Front Sights were slated for delivery on 06-15-2015, which would have been just enough time to get them out BEFORE I closed shop from 06-26-2015 to 07-24-2015 to take care of my mom. I am a one man show and family comes first. Now it looks like the Front Hooded Sights will be arriving while I am gone. No worries as my wife is here to receive packages.

So I am accepting "Pre-Pay & Wait Orders". I hate doing this as it is just not how I normally operate. I am doing this mostly because the news is already out and everyone is wanting to order so as not to miss out. I understand especially since I only made 500 units of the Black Diopter Rails and 100 of the Gray Diopter Rails. Sorry given the history of this product I only had so much ready cash to put towards production and I made as many as I could afford.

If you miss out... the next production would not be done until 11-15-2015 or about.

So by ordering you assure you spot in line. Any order that does NOT include a Hooded Front Sight will ship ASAP. All other orders will ship after I get back on July 25th in the order received.

The web site is tied directly to my inventory so if you can place it in the cart, it is available to purchase. You will need to check out right away as simply placing it in the cart does NOT take it from inventory... When you process the order / click submit order then you are assured the item.

As many of you know we have been at this for 7+ years. It was never a matter of... "Could we make it?", but rather "Can we make a quality product at a reasonable price?" Obviously anyone can make one of these for $1800.00 per unit... I should know as we made 2 prototypes at this price. But very few will be willing to pay that price.

The price you see above reflects the "Cadillac Version" with a Front Hooded Sight Included. By clicking the drop down lists "Customize Your Item" you will either choose the Cadillac / Full Blown Set or be allowed to (Opt Out) and save money.

So yes this is a set you are buying unless you choose not to.

This product is a True Plug & Play item. Just unscrew the 3 bolts that hold your rail on and place our rail on in it's place. There are no small metal tabs or shims to lose as ours is 100% self contained. We also provide 3 replacement bolts and an Allan Key Wrench.

The Rear Diopter Sight had to be connected to a rail in order for it to be low enough to line up with the ultra low profile of the Original Swiss SIG SANs Front Sights. Yes you can use the Original PE90 / 550 / 551 / 552 / 553 Swiss SIG Front Hooded or Non-Hooded Sights. You can NOT use the SIG 556 USA Hooded Front Sight or any other sight on the market except our MFI SIG SANs Hooded or Non-Hooded front sights.

MFI REAR Diopter Sight & Rail:

I designed these to look like the original SIG PE-90 / SG 551 rear diopter sights that were welded on to the receivers. The parts are NOT exact copies of the originals... Meaning that the parts of the MFI Rear Sight are NOT interchangeable with the original Swiss SANs parts. The design did not allow this and it was more cost effective to not even try.

The Rear Diopter functions exactly like the original and has the exact same markings as the Swiss SANs sight housing. The markings on the Drum / Diopter are also an exact copy of the original with the exception of the #4 which we changed from white to red... it just looked cooler.

As I am not a huge believer in the accuracy of the .223 / 5.56mm cartridge so I only fully tested the number 1 position at 100m. The #2, 3 and 4 designations may or may not be applicable. I did position the holes in the correct location, but not having the time or funds to waste on something I do not really believe in. While the #2 and #3 holes are the right size and position the #3/4 position hole is much smaller than the original and is NOT threaded for the insert of a target peep sight, nor is it likely to be at the correct angle as I do not have one to check against. The Diopter walls have not been counter bored on the inside either, so the walls are thick in that area to accept a thread. As I said... The hole is much smaller so that the customer could MILL a new hole at whatever angle they need and make it work. Sorry you are on your own on this one... just not cost effective to test / check 100% when 99% of the customers will never have the money to buy a SIG SANs target peep sight much less have the need to use it.

Fiber Optic Option: The holes for the fiber optic option in the rear Diopter are also smaller than the original. I did this so that you could buy the sight without the fiber optic and drill the holes out to fit the Tritium Ampules / Tritium Inserts. Due to the short shelf life, cost and pain in the ass import regulations I have no intention of ever offering Tritium anything for sale. Check the forums for suppliers.

Above is a photo showing you the two options side by side (with or without fiber optic).

Materials of Construction:

The Rail, Diopter & Diopter Sled are 4000 series cast aluminum.

The Windage adjustment wheel and other small parts are steel.

Finish: The Rear Sight & Rail are painted to closely match SIG 556 USA Model 551A1 Finish. This color is slightly darker than the Original SIG Gray found on the West Coast Armoury Rifles. The Rear Sight is made from special 4000 series aluminum alloy to allow it to flow more consistently into a mold. Unfortunately the non-aluminum alloys used (in particular copper and silica) make it impossible to anodize, so the rear sight and rail are painted like the originals were. The rear sight housing and rail are near 99% finished when they come out of the mold. We tried to retain many of the casting marks and even simulated some of the grind markings found on the original sight housings. I am not aiming for 100% perfection in a product as that is pointless and no cost effective. So if you have a safe queen that is worshipped rather than used... no MFI product is likely to live up to your standards.

At the front of the rail you will see a Swiss Style Cross and Shield. Additionally we have shaped the front of the rail to have a similar cut out that would normally be used for a scope mount, but in this case is strictly cosmetic. I spend a lot of time on the finer points of the design as it is critical to make any product as cool looking as possible. I hope you all approve.

Comes with: 3 - MFI SIG Top Rail Bolts and Allan Key

NOTE: Copying the original as closely as we did has it's advantages and disadvantages. While we try to maintain the look and style of the original rear sight any deficiencies that exist in the original design will likely come through as well on the reproduction. A good case in point is the Windage Adjustment Knob. Originally designed to use a Swiss Franc Coin to adjust, even the original SANs sights get the paint chipped or the edges of the adjustment slot scratched or damaged in some manner. For this reason we recommend that you adjust the knob by hand (yes possible) to avoid damaging the finish of the knob. The next best option is to use a coin (dime) with thin tape on it. The coin is what was originally used as the slot is dished to receive the rounded edge of a coin and NOT the flat edge of a screw driver.

MFI Front Hooded SIG 550/1/2/3 Sight: NOT AVAILABLE ETA 07-25-2015

Here is a link for photos and information (same as below) with prices if you wanted to order separately:

As mentioned the price on this page reflects the INCLUSION of a Front Sight. I will cover the basics of the Hooded Sight here as that is what most of you are looking for.

The non-hooded version has it's own page:

The MFI Front Hooded SIG 550/1/2/3 Swiss Style Sight is basically a direct copy of the original except in aluminum. The sight main body and flip up blade are made from 7071 T-6 Aircraft grade aluminum and are precision CNC. I choose aluminum over steel due to the cost effectiveness and versatility of the material. Obviously it would be pointless to make an identical sight to the original & have it be the same price or even more expensive. Additionally 7071 T-6 aluminum can accept a Military Spec. Hard Coat Anodized Finish making it very durable. The cross over windage adjustment wheel / donut and bolt are weapons grade steel and have a Mil. Spec. Black Oxi coating.

The Front Sight Fiber Optic Blade that flips up and down is interchangeable with an Original Swiss SANs Flip Up Blade with the Tritium insert. So "Yes" you can swap out the MFI blade for a SIG one if you so choose. Note that like all flip up fiber optic or tritium blades... the MFI blade is taller than the stationary front post / blade. I am not sure why SIG and for that matter everyone on the planet does this... I just choose to follow suit. In our case it does allow more light in and thus makes for a much brighter aiming point.

The Finish on the MFI Front sight is black only. This is because of the volume we expect to do is 95% black rails. Hard coat anodizing takes paint very well so if you want yours to be painted. Have at it... Personally I have always had an issue with the heavy coat of paint found on the original Swiss SANs sights (front and rear). Anodizing just looks so much more professional and clean.

The Front Sights comes with the Windage Adjustment Wheel and Allen Key. For those of you with Optics only weapons or do not currently have a front sight... The installation is a bit tedious... Go to this link for full instructions and tips.

Go to this page for Instructions on the installation of the front sight. Click on the "Instructions" tab:

Attention Quad Rail Owners: I have been informed by one Quad Rail owner that our Diopter rail does not fit plug and play with is 556P (Pistol Rail). The owner told me that it looks like he has to remove 0.0650" of either the MFI rail or the Quad rail to make it fit.

Sorry I never expected anyone with a quad rail to want one of these as this is a Retro Design. I designed this specifically to fit the Swiss SANs 551 or MFI 556P/2 Hand Guards and to be tight so as to eliminate some of the movement "slop" of the hand guard. I have tested the original SIG USA "SIG 556 Fish Gill" hand guard and the SIG USA Classic / SIG 556 / 551A1 hand guards and they fit fine as well.

So, Yes the MFI SIG 550 Style Diopter Sight & Rail is a hair longer than the stock SIG USA 556 rail. Again this will be a very tight fit for the 3 hand guards I mentioned. Going on is easy as you just press down, coming off is a little harder and in either case you can if you want undo the Diopter Rail (nothing falls out of the bottom like the SIG 556 rail thumb nail does) and reattach the rail. You will not lose zero on the iron sights as the tolerances of the 3 hole set up are very tight.


This item is NOT RESTRICTED FOR DOMESTIC US SALES in any way and we offer DOMESTIC USA shipping to ANYONE. We ship to all 50 US States as well as all US Territories i.e. Guam & Puerto Rico. Sorry we can NOT ship to ANY APO address regardless of actual location.

This item is 100% RESTRICTED FOR EXPORT OUTSIDE THE USA. The US Department of State regulates / restricts this product and it is NOT EXPORTABLE outside the USA even to LE, Governments or Military without State Department approval.

This approval is AVAILABLE through MFI as we are an ITAR / Dept. of State Registrant with the Directorate of Defense and Trade Controls Office. We can obtain a US State Dept. Export License for you.

Please feel free to contact us if you have any questions on this issue.

Shipping Information

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Customer Reviews

Comment Total Reviews (2)

Makes my 551A1 worth owning! Wow!!
  • Currently 5/5 Stars

Reviewed by: David06/13/2015 11:23PM

Product ownership: Less than 1 week

Purchased from: MFIAP.COM

I have been following this product for years and I cannot thank Mike at MFI enough for sticking with this project. I know how many problems he has had over the years with this.

Anyway I got one of each color, Black and Gray. So I will double post this on the other color too.

Fit is perfect. So easy to install and what a differance it makes. The black is almost a perfect match to my SIG 556 upper. Swiss style markings make this product even cooler. Love the Swiss Cross. I have only test fired perhaps 250 rounds as I just got this a day ago. Works perfectly at 100 meters. The 200m position on the drum appears to be right as well. I an not sure as I am using military ball ammo and I do not normally shoot past 100m anyway. I also really like the fiber optic option. I ordered the front hooded sight as well, but as I was in such a hurry to get one I bought the MFI non hooded SIG SANs flip front sight and everything lined right up and dead on. I cannot wait for the hooded sights to get in.

On the Gray Diopter... well this one went on my SIG 551A1 from CDNN and the color match is very close and may be perfect, but the MFI rail color is sort of a semi matt finish where my receiver and lower are more flat. Still way better that the rail that came with the 551A1. I also put the Black rail on the 551A1 and as I have black Swiss furniture on the 551A1 the black MFI rail actually looks great and not out of place at all. I have not shot the 551A1 yet.

Fit and finish are superb. I do not mind the casting marks as they are a reproduction of the originals I am told.

Again... THANK YOU MFI... a small company (one guy I am told) really came through!

I got 4... 2 good and 2 blems Great value!
  • Currently 5/5 Stars

Reviewed by: Romeo06/14/2015 12:03AM

Product ownership: Less than 1 week

Purchased from: MFIAP.COM

I bought both colors and in 100% good and also as blems.

Blems are hard to spot the damage unless you really look. Good ones are just perfect.

I have actually met the owner at SHOT SHOW a couple of times. Just a real guy who knows his stuff. I am so glad he is in charge of this product as so many others have tried (including SIG USA) and failed making expensive and crappy product.

I have most of the other stuff MFI makes.

If you ever get a chance to meet him, do so. He is not like the others in the industry. Seems to be a regular gun guy... Why California? Isn't that behind enemy lines?

Keep the great product and even better prices coming.


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