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Discussion Starter · #1 ·
It looks like the the XCR's top picatinny rail is about 1/2 inch higher than the buttstock when compared to
an AR15. Does anyone make iron sights that mount on a picatinny rail and sit lower than "typical" AR iron
sights? "Low"optic mounts are available but I've never stumbled across "low" iron sights. I know there
are "low" sights in the works for the Sig 556 but the the front won't work on a picatinny rail.
The other options would be a cheek riser of some sort but I'd prefer to not go that route.
 

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I'd say try it with a set of BUIS and see how it lines up with your eyes with a good cheek weld before worrying about a non-standard set. I've got Troy BUIS on mine and they are fine with my para stock.
 

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Discussion Starter · #3 ·
I don't like how AR sights line up on my Sig 556 and the XCR appears to have the same drop from the
rail to the buttstock. I'm going to contact RA and get the dimensions. I like to know what my options are before I purchase.
 

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Yes, the sights sit 3" over the bore on the xcr rather than 2.6" for an AR. I can't speak for the 556 since I have no experience with that rifle other than what vb3 has told me :p

That said, I like my troy buis on my xcr, and with the magpul ctr stock I really like the cheek weld I get. If I wanted a higher weld, I could get risers from magpul to put on the stock. This is an option for you to consider over the standard xcr folder.

You can also check out my post 'zeroing your xcr' for info about the trajectory difference inherent with the xcr.
 

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The XCRs sightline is slightly higher than an ARs. Whether this will matter to you or not will be something you'll just have to try and see.

When I first looked at an XCR about two years ago at Knob Creek, I found the YHM sights a touch high for me with the folding stock and about dead on with the Vltor stock. My own XCR is about the same with its folder and the KAC sights; just a touch high for my cheekweld. However, I"ve always planned on putting a Magpul M93 or (now) UBR. These should line up about perfectly for me with the KAC sights.

On the other hand, my optics line up fine and really the cheekweld with the folder is close enough it doesn't bother me much.
 

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Discussion Starter · #6 ·
Hmm, looks like I'm just going to have to get an XCR and see how it works.
I can always get a Magpul CTR though I'd rather have a UBR.
I wonder if the check riser that DSArms and Ace has for "tube" stocks will work on the XCR stock.

Now I just have to decide on caliber. 5.56, 6.5 or 6.8. I'd prefer 6.5 but I have no confidence that
the cartridge will be around 5 years from now and besides it hasn't even been prototyped, in the XCR, yet.
My next choice would be a SBR 6.8 but they're not shipping yet. :(
A SBR 7.63x39 would be nice but ...
I guess that leaves the 5.56.
 

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We T&E'd the S&W rifle today and I found the sights on the AR too low. It was very uncomfortable for me to have to mash my cheek onto the stock with the AR compared to how natural my XCR feels. Bottom line, I guess it was what you get used to as I had no problem with the AR sights before the XCR.

The other thing that suprised me is how much more recoil the AR has compared to the XCR. I never thought an AR kicked much but the first five rounds suprised me. My shooting buddy for today carries an XCR for work as well and actually had the charging handle pop him in the nose on the first round.

I even run my gun on "4" and it still recoils less than an AR.

On a side note the tactical S&W's are very very nice AR's. It was almost perfectly zeroed out of the box and very well put together.

LE price for both are less than a $100 dollars difference and even though the XCR is the higher, I would take the XCR every time for such a small difference.
 

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It looks like the the XCR's top picatinny rail is about 1/2 inch higher than the buttstock when compared to
an AR15. Does anyone make iron sights that mount on a picatinny rail and sit lower than "typical" AR iron
sights? "Low"optic mounts are available but I've never stumbled across "low" iron sights. I know there
are "low" sights in the works for the Sig 556 but the the front won't work on a picatinny rail.
The other options would be a cheek riser of some sort but I'd prefer to not go that route.
Learn to shoot the XCR before getting new sights

Keep in mind the XCR rail height is nearly identical to the AR15, which puts BUIS like the YHM at the same height as the A2 sights. Alex spoke about the XCR rail height somewhere, I forget, and says he wanted to maintain true compatibility with the vast market of BUIS on the market

Because the XCR does not use an "inline" design it creates something of an optical illusion which makes the rail seem higher, but in reality, it isn’t

Some advice though...

1. The XCR is not an AR15 so dont try and shoot it like one.

2. Do not place the butt against your shoulder, Place the toe of the stock against your shoulder for proper cheek weld

3. Don’t try and shoot nose to the charging handle. This is not correct. Set your head back slightly with your neck more erect and your neck less stooped forward.

4. The XCR factory folder is thin compared to an AR15 buffer tube. Do not twist your head and neck around the stock, but rather keep your head straight and line up the sights with your eye.

It's just a different weapon. I've handed my XCR to a few people who handled it like monkeys and couldnt get the gun to "work" for them. You're not going to smash your up against the receiver and stand like a hunchback and find the XCR to be comfortable. It handles different, but with practice the issues go away.
 
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VB,
So what kind of Irons do you reccommend? I still havent decided, and am not sure of all the issues as far as height and such.
 

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Keep in mind the XCR rail height is nearly identical to the AR15, which puts BUIS like the YHM at the same height as the A2 sights. Alex spoke about the XCR rail height somewhere, I forget, and says he wanted to maintain true compatibility with the vast market of BUIS on the market

Because the XCR does not use an "inline" design it creates something of an optical illusion which makes the rail seem higher, but in reality, it isn’t
It must be, or the chart in the zeroing post would be identical!
 

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I got the Midwest Industries sights that RA offers with the XCR. I think the front sight post is too high. When I fired it at a 12" diameter target (one of those "Shoot-N-C" targets) about 15 meters away I only started hitting it when I had the top part of the front sight pointing slightly above the target.

Do I need a short front sight post?

Regards,
Crashy
 

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The chart in the zeroing post is based on the statement that there's a difference in the height above barrel centerline. That's not the same thing as the height of the sights above the stock!

An AR doesn't have the gas tube and operating rod above the barrel with the rail on top of that. That accounts for the different height above the barrel between the AR and the XCR.

Has anyone actually measured the stock drop of both an AR and XCR? If so please post it here. I'm on the road so I can't measure mine and don't have an AR to compare it to anyway.
 

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Crashy, My gun came with midwest sights also. you have a frount sight adjustment. There is a pin on the sight that holds it in place. Push it down and rotate it clockwise will shorten it to bring your zero down. I had to bottom it out to get a 25 yard zero. There is a sight tool for this process but you can use two picks to turn the frount post.
 

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My Troy front sight adjusts the same way and it came with a nifty little tool to do it. Of course I haven't the slightest idea where that tool is now!

::)
 

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Crashy, My gun came with midwest sights also. you have a frount sight adjustment. There is a pin on the sight that holds it in place. Push it down and rotate it clockwise will shorten it to bring your zero down. I had to bottom it out to get a 25 yard zero. There is a sight tool for this process but you can use two picks to turn the frount post.
Same with my YHM sights. I lowered the front sight post about 9 clicks and it zeroed fine at 25 yards.
 

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It may be un-scientific, but my eye-ball calibrator does not deceive me. That is why I want lower profile sights. Apparently, as if we didn't know, the entire picatinny rail industry revolves around the AR/M16/M4 world. That which originated with having sights way above necessary to accomodate a friggin carry handle, something we were never allowed to use in the ARMY (Marines too)!! Thanks Air Force circa 1958 or 9 (or sometime around there). Yes, that is the only reason why it's like that.

Edited to add:

The reason for the carry handle was that it was designed at the request of the Air Force waaay back in 19-fifty- something (AR nerds, chime in to correct me) for their Security Police. When suggestions came in as to the design of the M16, some General(s) thought it would be "neat" for their SP's to be able to "tote" around their uber light weight futuristic plastic rifle like some sort of purse (AF guys, please don't flame me, but that is what happened). I guess it would look "fabulous" with their new berets or something. It stuck ever since then. But even now w/removeable CH, the front sight base stands like the empire state building, hence the rear sight has to accomodate. Hopefully, now w/monolithic AR uppers, guns like the XCR, SCAR, and others, this will go away like the Do Do bird.
 

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Here, I cut and pasted this directly from Wiki, the all knowing source of the universe;

Wikipedia http://en.wikipedia.org/wiki/M16_rifle
Another distinctive ergonomic feature is a carrying handle on top of the receiver where the rear sight is located. This design is a by-product of the original design where the carry handle served to protect the charging handle (see my comment below)and mount a scope.[5] In practice, the handle is rarely used to carry the weapon; holding the weapon by the pistol grip provides quicker response time while a shoulder sling provides a more convenient option when response time is not a concern. More importantly, with the sight plane 2.5 inches over the bore, the M16 has an inherent parallax problem that can be confounding to shooters. At closer ranges (typically inside 15–20 yards), the shooter must aim high in order to place shots where desired.


I'm looking right at my M4 and any rear sight w/dog ears would also protect charging handle (tea-handle for those of you that call it that-just thought I added that b/c someone at work called it that yesterday-jeeze!!).
 

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Crashy, My gun came with midwest sights also. you have a frount sight adjustment. There is a pin on the sight that holds it in place. Push it down and rotate it clockwise will shorten it to bring your zero down. I had to bottom it out to get a 25 yard zero. There is a sight tool for this process but you can use two picks to turn the frount post.
Same with my YHM sights. I lowered the front sight post about 9 clicks and it zeroed fine at 25 yards.
Ok. It looked like I needed to crank it all the way down, but I thought that was weird. Thanks for the responses.

-Crashy
 

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Discussion Starter · #19 ·
I measured the distance from the top of the picatinny rail to the top of the stock
tube on a Sig 556 and a S&W M&P.

16.5 mm for the S&W M&P
26 mm for the Sig 556

My method
a) lay a straight edge along the picatinny rail
b) measure from straight edge to stock tube

It would be nice to get this measurement for the XCR. ;)

SB
 

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25 to 26mm. I don't have ruler in metric. I got it at 1" on the money.

And while I have it out, 2 5/16th inch (58mm) from approximate peep sight center (ARMS 40) to top of stock.

Compared to:
1 7/8th inch (47mm) for an AR
1 15/16th (49mm)for a Steyr AUG
1 7/16th inch (36mm) for an AK
1 13/16th inch (46mm) for a G3/Hk 91 w/a collapsible stock
1 1/2 inch (38mm) for a SA58 (FAL) Para.

These are approximate measurements, some eyeballing involved. But it is obvious we need some sights that are at least 1/2 inch shorter or modified stock.

Either way, it's a minor thing to me, but I'd still get lower sights.
 
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