I know this is a deep, deep rabbit hole. I stole a gen 1 556 last weekend for a song. I already have a SWAT Patrol version with a red dot and BUIS. But this latest one came with an aftermarket quadrail and no optics. I'll throw on some Magpul BUIS, just to get started. But I don't know what else to put on it. Magnifier, simple Romeo 5, or what. I don't want to get too deep into this, but am willing to spend some $$ to make it right. What to buy?

I have a 556 in a similar setup with a Troy quad rail. I have Magpul MBUS and a Primary Arms Advanced Micro dot. I prefer the micro dot on the 556 to keep the weight down.

Thanks. Do you have it co-witnessed and/or on an elevated mount?

Did you check to see if the rail is canted?

quote:

Originally posted by DCFD4:
Did you check to see if the rail is canted?

Rail cant on the rifle and on the scope rings do factor into long range shooting to preserve riflescope elevation range.

You could put a 1-6x25 FFP scope on it with a pigtail and also buy a 45 degree offset mount for a red dot. That would cover a lot of bases.

It sure is easy to spend other people's money.

I don't know how to tell if the rail is canted. I think it's aftermarket, but I just threw on the Magpul flip up sights so I can at least try it out at the range. Not sure how much I want to put into this. I really want the Swiss handguard, but they look pretty hard to find now. I'd like to put a folding stock on it too, but don't know if that's possible on the first generation ones. It's gonna be a cool project gun. No rush to get it all done.

quote:

Originally posted by Rick Lee:
I don't know how to tell if the rail is canted. I think it's aftermarket, but I just threw on the Magpul flip up sights so I can at least try it out at the range. Not sure how much I want to put into this. I really want the Swiss handguard, but they look pretty hard to find now. I'd like to put a folding stock on it too, but don't know if that's possible on the first generation ones. It's gonna be a cool project gun. No rush to get it all done.

The rail cant will be on the upper receiver. That is where the optics are usually mounted. You should be able to call the manufacturer or look up the detailed specs online or in the operator manual, also online.

https://www.sigsauer.com/media...ources/SIG556R-1.pdf

I just searched this manual and the only "cant" I found was in lubricant.

A canted rail or mount isn't necessary for a carbine that will be used at typical carbine distances -- with irons, red dot, or LPVO. If the cant exists -- fine. If it doesn't exist -- fine.

Many red dots and LPVO have elevation adjustment capabilities of 100 MOA or more. Divide this in 100 MOA half for useful up elevation capabilities. Subtract 3-5 MOA to get a zero. So...said 100 MOA LPVO with a flat base has 45-47 MOA of up elevation. At 5,000' Density Altitude (a summer day at maybe 2,000' absolute elevation) with FGMM 77 on my 16" carbine, that allows me to dial elevation for 950-970 yards. Which is beyond the capabilities of just about any AR15 & ammo combination I can think of.

In other words...canted rails/mounts are for long distance precision rifles, which a Sig 556 is not.

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Consider your intended target distances, target sizes, accuracy requirements, desire for magnification, eyesight capabilities, weight requirements, and maybe a number of other personal factors before buying a sight system. Once you have narrowed the parameters of intended use, sight system suggestions will be more helpful.

Right now, you might as well be asking "I want to buy a car. What should I buy?"

quote:

Originally posted by Rick Lee:
I don't know how to tell if the rail is canted. I think it's aftermarket, but I just threw on the Magpul flip up sights so I can at least try it out at the range. Not sure how much I want to put into this. I really want the Swiss handguard, but they look pretty hard to find now. I'd like to put a folding stock on it too, but don't know if that's possible on the first generation ones. It's gonna be a cool project gun. No rush to get it all done.

This was a CQ issue on some of the early versions. SIG replaced mine that I bought new in 09 because of this. The pic rail was installed sloping off to one side. Flip the rifle over and stand it on the rail on the corner of a table or countertop. If it stands straight and tall you're good. If it leans several degrees to one side then your rail is canted

I'm not a fan of the super high optics mounts. I use an absolute co-witness mount with a Magpul MOE stock with the lowest riser.

quote:

****
Consider your intended target distances, target sizes, accuracy requirements, desire for magnification, eyesight capabilities, weight requirements, and maybe a number of other personal factors before buying a sight system. Once you have narrowed the parameters of intended use, sight system suggestions will be more helpful.

Right now, you might as well be asking "I want to buy a car. What should I buy?"

Ok, I probably won't shoot this more than 25-50 yds. My eyesight does not work to 100 yds without a scope. The flip up iron sights are just for my backup, as I have gotten all set to shoot before and then the battery in my red dot was dead.

My other 556 SWAT Patrol is pretty well dialed in and will likely always be my go-to. But I want this latest one running right too.

Based on what I've seen, you're as likely to get a canted rail as a flat one. I've seen the canted rails on both US and Swiss guns.

Then my recommendation would be to get a red dot that also hase a 65 MOA circle. Sight level at cowitness. Then zero at 50/200. The Sig Romeo5XDR is an older model, but allows you to do all of that at a reasonable price. It has a "shake awake" feature to keep your battery life long.

Thank you. I'm shopping now.

I picked up a sig romeo 5 gen1, came with 2 mounts high and low for an ar. My grandson tried it on his sig 556 with the low mount, and said it co-witness with original front sight. I haven't checked it but will affirm if this true, this weekend.


Edit: Yes romeo 5 does co-witness with supplied low mount on a 556.

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This message has been edited. Last edited by: Greymann,

quote:

Based on what I've seen, you're as likely to get a canted rail as a flat one.

Its been many years since my 556 addiction, but as I understood it back in the day the cant issue affected only the 3 screw guns. Your a wizard on the 556 was that true? In any case all of mine (qty4) were canted. And the aftermarket rails fixed it (which might be true for the OP).

I have a Swiss 553 and a Swiss 553R that both have top rails that are canted. Three screws, four screws, no screws (welded); apparently it's just difficult to put a rail on top of these rifles.

i doubt the rail is canted. i think that affected the original 4 hole receivers. not exactly sure, been a while. if its a 3 hole (3 screws) it is most likely ok. also an aftermarket troy or samson rail is normally "monolithic" to the gasblock...should be pretty good to go. for sights and optics id stick to a low mount micro type like a romeo4/5 or holosun? would be just fine. with the original swiss stock, AR height is a bit too high. if it has an ar receiver extension, then any CTR style riser can help with cheek weld.

Pretty good deal here Rick: https://palmettostatearmory.co...ifier-sorj5x201.html

Yeah, probably gonna snag that. Thanks.