Difference between Weaver and AR-15 flattop rails?

[heypete]

Greetings all,

I'm looking at getting a Trijicon Reflex II sight for my Kel-Tec SU-16B.

Alas, the sight does not come with a mount, but several are available. There is the RX11, which fits Weaver rails, and the RX14 which fits AR-15-style flattop rails.

The rails on my Kel-Tec those on my friend's AR, but he also said that there's no difference between the two types. The only difference between the mounts, he says, is that the Weaver mounts tend to be a lower (which I'm looking for), while the flattop mounts are higher, so one can co-sight the reflex sight with the iron sights if one so desires.

I tried his flattop mount on the Kel-Tec, and it held it quite a bit higher than I found comfortable -- instead of a cheek weld, it was more like a chin-weld -- so I'm considering the lower Weaver mount.

Before purchasing it, though, I wanted to confirm here that this would indeed be correct.

[Mods: Not sure if this should go here or in Firearm Accessories, but I chose this group as it seems to be a general question and doesn't necessarially apply to this particular product. Feel free to move it as necessary.]

 

[Preacherman]

It's not so much a matter of the rail as of the mount on the sight. Mounts designed for the AR-15 are typically intended to put the sight higher up, to enable its use with that particular stock design. A Weaver mount is a general-purpose mount, designed to fit many rifles with Weaver-style rails.

 

[heypete]

It's not so much a matter of the rail as of the mount on the sight. Mounts designed for the AR-15 are typically intended to put the sight higher up, to enable its use with that particular stock design. A Weaver mount is a general-purpose mount, designed to fit many rifles with Weaver-style rails.

Ah, ok. Well, I certainly don't want it to be higher up, so it looks like the Weaver one would be the right one to get.

The physical rails themselves are the same, right?

 

[Preacherman]

Not necessarily. A Picatinny rail (which AFAIK is what's on most AR-15's) has slightly different rail size and spacing to a Weaver rail. Generally, Weaver mounts will fit on any Picatinny rail, but a Picatinny mount may not fit some Weaver rails. Do a Google search for more info - there's lots out there.

 

[heypete]

Hmm. Ok. Yeah, I noticed that when trying to fit his Picatinny mount on the Kel-Tec rails -- the spaing between the ridges on the rail required some gentle application of a file to shave off ust enough material (fortunately the rails are plastic) for it to fit.

FYI, I ordered the Weaver mount for the sight, so it should hopefully fit without any trouble. I'm going to leave the iron sight on there (the rear one is removeable), and they're properly zeroed at 25 yards to the Army zeroing target -- if the reflex sight ever breaks, I can simply remove it and use the irons.

 

[Onmilo]

The AR mount will allow you to calibrate the reflex sight to the iron sights, if there are any on the rifle.
A Weaver mount platform will put the sight too low and you won't be able to regulate the reflex sight properly on an AR using this mount.