At the end of the day, a sharp impact will still overcome the friction causing a shift between the barrel nut and the rail.
Many rails rely on friction to clamp the rail onto the barrel nut like a hose clamp (geissele, wedgelock, bcm) or bolt into the barrel nut (Noveske NSR, alg emr), thus requiring a long barrel nut. This is where shift/ flex is most likely to happen- and I have experienced it on highly regarded rails. In my experience the biggest weakness of a rail is the interface between the rail itself and the barrel nut. generalizations of course, but it probably reigns true
The rail will only be as strong as the weakest part, and that'd be (assuming no crazy lighting cuts), right after the barrel nut ends where the 1/8" extruded alum is no longer supported by internal means. you can see the barrel through the QD mount. Pics of the long urx4 "barrel nut"? it's engagement only looks like it's about the dept of the upper threads + barrel flange. None of my G or Hodge rails are even close to that amount of material. The "barrel nut" portion is just as long, and is thicker than a G or Hodge barrel nut.Įdit: The "barrel nut" leaves about 1/4" of gap between it and the actual barrel itself. don't see the URX4 excelling in any of those aspects, but blind brand loyalty is a thing I would imagine the length of the barrel nut (the longer the better) along with thickness of the extrusion of the rail, would add up to seeing the most benefit in regards to rigidity. Tons of arbitrary options given based of bias and a "just cause" mentality. I would say any of these rails would be plenty strong enough for the OP but if he’s serious about hardmounting an AR by the handguard he needs to pony up for a monolithic upper. Otherwise all any of us are doing is speculating and sharing thoughts I don’t know of any such study or testing so if you have something I’d love to read it. Then maybe another rail is all one piece but a bit thinner (in theory) so maybe it has the possibility of bending. I mean, sure maybe there’s a rail thats thicker than another but it uses a separate barrel nut so theres a possibility for slippage. I would say there are multiple quad rails that are more rigid than the URX4, including ones from KAC, due to thickness and weight alone.Īnd you wouldn’t necessarily be wrong, but you wouldn’t be right either. Larue ultimate upper and even their standard rails are very strong and the LAT/SAT rails are a great value. Now if you don’t have “KAC money” than your question changes and you’ll get different Answers. The Larue and Hodge are great options, but you asked for the “absolute” most ridged handguard and aside from a monolithic upper that’s the URX4. In any case, your best choice here would be a monolithic upper, it would be the best way to isolate the forces you’re talking about. Either way, those forces are being imparted to the receiver in one way or another, so I’m not entirely sure what your concerns are, is it rail deflection or receiver flex? On top of that, short of a handguard that bolts to the actual receiver, bolting a rail to a barrel nut will impart those same forces to the upper receiver extension flange/threads. That sounds like a seriously niche use case.
I would not want all that force to be transferred to the barrel retention threads. Similar to a tripod rig, but heavy duty with the tripod being fixed and the gun subject to forces from the user. One possible scenario would be hard mounting the weapon to a large base, using the handguard to adapt to the base. Unless you’ve got a specific niche case that is relying upon the absolute smallest shift/flex possible, it just isn’t something that’s going to matter for the vast majority of end users, at least IME. It can also give you greater versatility for mounting accessories, and it can enhance your shooting accuracy.At a certain point, you’re getting into the realm of diminishing returns. An AR15 hand guard, your personal selection, can help improve your rifle’s comfort.
Round free float rail ar15 install#
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