What railed handguards do you consider "optic worthy?"

[mkmckinley]

We've had a few discussions on rails and their various merits on here in the last few weeks and it's got me thinking. What rail systems would you consider stable enough to mount your optic onto? The closest thing I have first hand experience with is mounting an LA-5 on a M-4A1/KAC and a Mk-18/RIS II. I've never noticed a significant zero shift but the LA-5 is not exactly a precision aiming device.

[jonconsiglio]

I've never found a need to mount an optic past the front of the upper receiver. If I did, I'd be pretty confident in the DD Lite rail and RIS II. If it was a work gun that I was betting my life on and was getting banged around a good bit, I would only trust that set up on an MRP, Vis or a SCAR since they're one piece.

Then again, people have been mounting lasers on their hand guards for years with good results. Maybe it wouldn't be too bad. I honestly have never really thought about it.

[wahoo95]

Not well known, but the Barnes Precision Machine rails are probably the most stable and solid mounted that I have seen. They were designed to have optics mounted to them for MIL/LEO applications. Definitely worth a look.

[The_War_Wagon]

DD Lite - astigmatism makes me push the optic out onto three such rails.

[aziator]

Any of the DD rails will maintain zero with an optic out there.

[Failure2Stop]

None.
You are stronger than your rails.
With pressure you can seriously affect zero, even with the top of the line rails.
I mount lasers on my HG because I have to, not because that's the best place for them.

[SIMBA-LEE]

AR rails aren't meant for precision optics. Unless you have no other choice, don't do it.

[Belmont31R]

Agree with none. They all will flex under pressure. A shift of one degree will be over 60" at 100 yards.



1 degree is 1/360th of a circle, and 1 minute of angle is 1/60th of one degree. So if the rail is flexed one degree up thats 60 minutes of angle, and one minute of angle is 1.047" at 100 yards.

[mkmckinley]

I suppose an aiming laser isn't precise enough to really notice a lot of shift in the rail. Of course during zeroing to do your best to keep the pressure on the rifle constant and during training and real life use you're not going down range to check your shot group. All off the non-monolithic free float rails I've ever hand'ed have allowed me to flex the rail out of alignment with the barrel with mere finger pressure. I always wonder how closely it returns to its original position after I'm done screwing with it. The KAC RAS M4 handguard has always seemed a lot more solid in that respect but I'm not sure now much it matters in practice. Also, how much of the flex in the rail to handguard relationship is coming from the rail and how much from the barrel itself flexing or flexing at the barrel nut? And yes, I have too much time on my hands these days.