AR Flat-Top rail question

[BrokenPaw]

I just took advantage of the AWB sunset and bought all of the parts to build out a nice little carbine (A4 upper, collapsible stock, and lower parts kit from RRA, and bare DPMS lower receiver, because RRA wanted to be a pain about the FFL transfer).

I have an EOTech 512 holosight on my Bushie M17S, and I absolutely love it. I'd like to get one for my new carbine, as well.

Is the rail on the top of the A4 a Weaver/Picatinney, like is on the carry handle of the M17S? Or will I need an adapter of some type to put the holosight on the flat-top?

Also, what's the difference between Weaver and Picatinney rails? The EOTech sight comes equipped to attach directly to a Picatinney rail, but it also comes with a "Weaver Bolt", which looked like it'd go right in one of the grooves on the M17's accessory rail. What's the function of the Weaver Bolt?

-BP, feeling silly for not knowing this stuff.

 

[meathammer]

Your Eotech should mount with no trouble. I have one on my flattop Armalite. As far as the bolt goes, are you referring to the separate thumbscrew bolt it came with? There should be no difference.


--meathammer

 

[Bartholomew Roberts]

Anything that goes on a weaver rail, will work on a Picatinny (1913) rail, including the EOtech.

Also, what's the difference between Weaver and Picatinney rails?

http://www.thefiringline.com/forums/archive/index.php/t-143104.html

 

[BrokenPaw]

Thanks, guys. Now all I need to do is order the EOTech.

Meathammer, yeah, I was referring to the spare thumbscrew bolt that came with the holosight. The sight mounted on mt Bushie without the bolt, just by clamping its little legs down on the rail. Instructions said that using the bolt was optional, so I left it off. Is it just available to ride in the rail groove, to prevent recoil-induced slippage?

Range report and photos will follow when the parts come in and I get the thing all built.

-BP

 

[Mr. Hankey]

I found that the EO Tech sat too low, when mounted directly to my flat top.

You may find you'll want to get a riser.

 

[ietrash]

The Weaver bolt will replace the Allen screw, so you can remove/replace the EOtech with a coin, instead of having to remember to bring an Allen wrench.

 

[BrokenPaw]

You may find you'll want to get a riser.

Mr. Hankey, I was sorta thinking that the sight might sit too low on the flat-top. Do you have any suggestions about where is a good place to obtain a riser?

IETrash: Hmm. I wonder if that's more a misfeature than anything else; if I can remove the thing with a coin, so can anyone else on the range, when I'm not looking. I'd probably miss a whole rifle if it got nicked from my shooting bench, but if the rifle were there and the sight were gone, I might not notice...

-BP

 

[meathammer]

Broken Paw,

A few months ago I ordered the A.R.M.S #38 http://www.armsmounts.com/catalog.php?action=124&item_id=32 .

I wanted a BUIS on my rifle and the height of the Eotech seems perfect now. It raises the optic another 1/2 inch or so. The flip up rear sight does not co-witness, but I didn't expect it to.

Using the thumbscrew on the Eotech, you can remove it very easily to use the irons. Reattaching the Eotech showed minimal loss of zero.

One thing to note with the A.R.M.S BUIS is they are designed to be used with a Colt front sight post. (which is taller) You can order these from Bushmaster for a couple of bucks.

I know you didn't ask about any BUIS, just thought I would share my setup.

Added: Bushmaster has risers that should work since the area where the Eotech clamps on isn't very big.

Bushmaster Risers


--meathammer

 

[ietrash]

Quote:
____________________________________________________________

IETrash: Hmm. I wonder if that's more a misfeature than anything else; if I can remove the thing with a coin, so can anyone else on the range, when I'm not looking. I'd probably miss a whole rifle if it got nicked from my shooting bench, but if the rifle were there and the sight were gone, I might not notice...
____________________________________________________________

If I had to worry about people robbing parts off of my gun while I'm hanging targets, I'd find a better place to shoot.

(BTW, somebody can remove your entire upper and lower with the tip of a cartridge.)


(edit because I can't spell)

 

[BrokenPaw]

If I had to worry about people robbing parts off of my gun while I'm hanging targets, I'd find a better place to shoot.

I'm not actually very much afraid of having my stuff stolen. Mostly it's just my cynical side coming out.

(BTW, somebody can remove your entire upper and lower with the tip of a cartridge.)

Ok, yes, there is that. Probably easier than taking the sight off in any case.

-BP

 

[BrokenPaw]

If I had to worry about people robbing parts off of my gun while I'm hanging targets, I'd find a better place to shoot.

I'm not actually very much afraid of having my stuff stolen. Mostly it's just my cynical side coming out.

(BTW, somebody can remove your entire upper and lower with the tip of a cartridge.)

Ok, yes, there is that. Probably easier than taking the sight off in any case.

-BP

 

[Mr. Hankey]

Mr. Hankey, I was sorta thinking that the sight might sit too low on the flat-top. Do you have any suggestions about where is a good place to obtain a riser?

I bought mine from Tapco

http://www.tapco.com/product_information.asp?number=MNT0930&back=yes&dept=194&last=21