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Discussion Starter · #1 ·
What EXACTLY Classifies a "Mil-Spec" Rail?

Could someone elaborate what EXACTLY defines mil-spec rails? We all know our beloved XCR's have channels in them.....so how does this make them "unmil-spec" as stated another place?

My understanding was always the distance of grabbing points (width, depth, and spacing) is what makes a 1913 STD mil spec rail, which the XCR meets.

If you can correct me, I'd appreciate it. 8)

My final question is, does RA consider this rail to be MIL-STD-1913?
 

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Re: What EXACTLY Classifies a "Mil-Spec" Rail?

Picatinny rail
From Wikipedia, the free encyclopedia

M4A1 Modular Weapons System carbine with M1913 rails on upper receiver and foregrip
Picatinny Rail Dimensions, Cross Section (dimensions in inches)The Picatinny rail (IPA: /?p?k?t?ni/ or /?p?k??t?ni/) is a bracket used on some firearms in order to provide a standardized mounting platform for telescopic sights and other accessories, such as tactical lights and laser sighting modules. The standard was first published by the Picatinny Arsenal and carries the official title MIL-STD-1913. It is also known by the NATO designation STANAG 2324.

The rail is typically placed directly on the weapon's receiver, in the position normally occupied by the rear sights. The rail's cross-section is shaped roughly like a wide T. Scopes are mounted on the rail either by sliding them on from one end or the other, or by means of a "rail-grabber" which is clamped to the rail by means of bolts, thumbscrews or levers.

In order to provide a stable platform, the rail should not flex as the barrel heats and cools. For this reason Picatinny rails are cut crosswise, to give them considerable room to expand and contract lengthwise. These slots are also standardized in size, and many accessories use them for locking purposes. The Picatinny locking slot width is 0.206"(5.2324mm). The spacing of slot centers is 0.394"(10.0076mm) and the slot depth is 0.118"(2.9972mm
).
If you want to get real technical you can read this...

http://www.quarterbore.com/library/pdf_files/mil-std-1913.pdf

If you ask me I say it is Mil Spec.
 

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Discussion Starter · #3 ·
Re: What EXACTLY Classifies a "Mil-Spec" Rail?

I read it, and as pointed out on the other forum, it says it has to look exactly like figure 1. So I guess it isn't....................


MIL SPEC!


Anyone want to buy this stupid XCR? I feel duped!













;D
 

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Re: What EXACTLY Classifies a "Mil-Spec" Rail?

On the 30th of this month I am going to order one of those stupid XCRs. I know my Eotech 552 will fit on it, so that is all the 'spec' I need....'nuff said. Oh, by the way, I have a tendency to buy two of everything, so.......
 

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Re: What EXACTLY Classifies a "Mil-Spec" Rail?

Well, if you look at the rail of an XCR from the same profile view as depicted I would say that it looks the same.
 

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Re: What EXACTLY Classifies a "Mil-Spec" Rail?

There's Picatinny std & Weaver std. You can't tell the difference without a micrometer. I believe picatinny is the M1913 "mil-spec". Mil-spec doesn't have the relief cutouts in the middle (which I ASSume saves a little weight).

You should sell your XCR cheap, and let me buy it, just to dupe me too. ;D
 

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Discussion Starter · #7 ·
Re: What EXACTLY Classifies a "Mil-Spec" Rail?

You should sell your XCR cheap, and let me buy it, just to dupe me too. ;D
Well, if you have one also, how about you just sell me yours cheap since I already feel duped? ;D

Honestly, if a couple other guns weren't coming out possibly this year, I'd already have a second XCR. I've got nothing but GREAT things to say about it!
 

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Re: What EXACTLY Classifies a "Mil-Spec" Rail?

Look at a KAC rail if you want a first hand example of true mil-spec.

Awhile back I made a list of recommendations and making an XCR with true mil-spec rails that were T-marked were on it
 

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Re: What EXACTLY Classifies a "Mil-Spec" Rail?

How much weight is actually saved by lightning cutting the rails?
Is there any reason to do it other than weight?
 

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Re: What EXACTLY Classifies a "Mil-Spec" Rail?

How much weight is actually saved by lightning cutting the rails?
Is there any reason to do it other than weight?
Few ounces I am guessing. Not a ton. And there isnt a good reason other than weight IMHO
 

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Re: What EXACTLY Classifies a "Mil-Spec" Rail?

Not much, but it's not an absolute weight issue, it's about balance.
 

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Re: What EXACTLY Classifies a "Mil-Spec" Rail?

Not much, but it's not an absolute weight issue, it's about balance.
Isn't balance about weight distribution, so in the end, it is all about weight right?
I'm not trying to be a smart ass, just backing up my own thought process with clarification...
 

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Re: What EXACTLY Classifies a "Mil-Spec" Rail?

Yeah, my XCR's got a 16" H-bar and it's fairly nose heavy . I'm on the waiting list for a 12" lite bbl. and that should really make a difference. I'm probably keep this 16" bbl and have it recontoured into a lite bbl because short bbl's are LOUD without a silencer (which I already have)

cheers, R20
 

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Re: What EXACTLY Classifies a "Mil-Spec" Rail?

Yes and no. Half an ounce from the tip of the barrel will have more effect on balance than half an ounce taken from the handguard, which is usually in front of the center of gravity and the center of intertia. Simply lightening a rifle can make it handle like crap.
 

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Re: What EXACTLY Classifies a "Mil-Spec" Rail?

True, I have several AR's. One is a maxed out heavy barrel w/freefloat HG, Surefire M900, EOTech, ATN laser, VLTOR tele w/batteries, and it's too heavy (and way too expensive). My favorite to carry is just a little A2 light bbl. That's my KISS rifle (no Terra, I don't kiss my rifle ;D ).
 

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Re: What EXACTLY Classifies a "Mil-Spec" Rail?

How hard would it be to reprogram the machine not to do the cut through the middle?
 

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Re: What EXACTLY Classifies a "Mil-Spec" Rail?

Do you mean on the XCR's. Should be no prob at all if they wanted. Just a little reprogramming of the CNC.
 

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Re: What EXACTLY Classifies a "Mil-Spec" Rail?

How hard would it be to reprogram the machine not to do the cut through the middle?
I have been nagging Alex about that for 2 years now. He always answers my requests personally and promptly and while most of the things I request (ambi mag release, etc) he says are in the works, unfortunately that is not one of them. I think he should do it if only to eliminate at least 4 passes with the CNC machine which would speed up production.

On the other hand, I have not had a problem with my Larue LT104 on my XCR. The edges of the cross bar com in contact with the rail on the XCR. I still would prefer a full profile rail and have indicated to Alex I would buy 3 new uppers if he did that. For what its worth, I tried to get Mark Larue to increase the width of the cross bar on his mounts but he said no.
 
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