Where are we at on quad rails? My newest design is a DD RIS II, and I’ve noticed that some others are slightly thinner and significantly lighter. I mostly shoot MLok URX4 guns, but a buddy of mine that wears size L exam gloves is considering a quad rail for a 14.5” P/W. If not pic rail, he’ll probably end up with a Mk8. I wear a size M exam glove, but helping him research a bit has made me curious, since they don’t look as thicc anymore.
Those of you still using quads: which ones, and why? Numbers, such as dimensions and weights would be very useful. Needs to hold zero with a PEQ after riding in the bed of a truck, having a trip and fall, or just being dropped. M203 mounting is not req’d.
Larue: heavy and stout, a little difficult to install, the abbreviated bottom gives it a kinda rounded/pear shaped feel which inlike.
DD Omega: I think these only came in 7" and 9" lengths but they’re thinner than they are tall (think I-beam) are lightweight and feel slim in profile.
Geissele: I use MK4’s and MK8’s as well as the originals. I lump these in with actual quad rails due to their shape. Installation is easy and very strong. My favorite is actually the original SMR as the corners are slightly rounded giving it a very round feel when held in hand.
Thanks for the reply. The DD RIS also has a not-so-tall bottom, giving it a good feel for its size. Probably not as pear shaped as the Larue, though. Docsherm has preached the Larue rail quite a bit.
The Mk8 with Magpul covers is basically the same thickness as a quad with thin covers. In fact, a quad with ladders might even be a hair thinner. It looks like some lazy engineer went “eff it; just shave the cross slots off a pic rail if these sissies want a lighter rail”. Ironically, it has aged well as a competitor to the current crop of floppy ass skinny handguards because of that.
I’ve also not used them, but they are well-liked on the internets and they seem like they would be at the top of the heap. I wish someone carried them locally. Reminds me; I have a buddy with one on a SBR that I should mess with next time we link up.
Edit: looking at the C4 spec sheet again, and my own RIS, it looks like the C4 is very roughly a tenth taller and a tenth narrower than the RIS. Reads like it is narrower all around than the Mk8, if rail covers are used on both.
I have a KAC FF RIS on my Slotty Colt. Once I get a URX4 or a G Rail; it’s getting switched.
I only kept it on so long out of habit. I doubt that I am going back to a quad unless it is for a period piece like my Rifle length URX II. I never got one when they were “the thing” but was enamored with them and have for my KAC stripped lower build. I just want a few more period correct pieces for a 2007 era gun.
Still Run KAC RAS on guns. The BCM QRF is my second favorite based on profile and price. I have one Centurion which is outstanding, but my only gripe is the tall bottom rail. It bugs me. I like rails that are close to DD RIS or KAC RAS dimensions… which BCM’s QRF is.
BCM is the last rail I bought and would be my go to if I needed another one.
My go-to free float rails are DD RIS II (FSP or not) and KAC rifle length FF RAS.
Non free float rails are KAC M4 RAS.
I like the larue rails because of their design with a tucked in bottom rail and the built in QD.
I’ve used keymod and mlok rails and never really had a like or dislike for them. My bolt gun currently uses mlok and I had a DD rifle with keymod. I can take them or leave them. My preference is for standard pic rails because of the grip I get with them and I think the mounting of accessories is more solid.
I really, really like the Larue for its “Short” bottom rail and “Skinny” profile. Put a Knight panel on the bottom with ergo ladders on the sides and it feels good, with thermal protection when you get to shooting a bunch of magazines (not the proverbial “Mag dump,” but shooting lots of targets). Con going against it is spotty availability during covid craziness.
The Daniel Defense Omega free-float drop-in is a good choice if it’s an issue gun and you’re not allowed to modify the base weapon (i.e., driving out the sight base pins and replacing the barrel nut and delta ring assembly) under threat of military non-judicial punishment.
If it’s your gun and you are required (by unit or department policy) to keep quad-rails then I’d try a BCM QRF. I bought one last month for a full-length M16A4 equivalent for $150 from Primary Arms. It’s a little “Fatter” than the Larue but not objectionably so. The SLR Rifleworks and Midwest Industries options are good-to-go as well.
I have a couple of Centurion Arms rifles, one is 11.5 with a 10" C4 quad rail, and the other is a 14.5 with a 12" C4 quad rail. I really like these rails. Very solid, very stout, and very well finished. No mistaking the quality of these rails. If I’m buying another CA upper, I’m probably going to go with another C4 quad rail, even though CA offers a plethora of rail choices.
I have a DD RIS II FSP and an Omega 9.0 and a Geissele MK4 hybrid. I do like pic rails and have been thinking of picking up a Geissele MK7. I have a couple Centurion rails but they are both M-Lok.
I must admit that between the KAC and Larue free float quads, the Larue was superior. That’s what I made that one LMT upper with. If I seriously had to pick, it would be admittedly Larue
Exactly why I went with the Omega in 7" length. I’m curious, since it mounts on a GI barrel nut, how much flex would longer lengths have? Considering that the GI nut arrangement called for attachment points on both ends of the handguard. I suppose the same question could be applied to the C4 rails.
Thats a good point that I did not consider. DD’s method seems similarly sub-optimal in the barrel nut, as well. Does the QRF take a beating and hold zero? Does it flex excessively when side loaded, like with a sling?
The DD bolt up is more like a unión that pulls on the back face of the barrel nut, the BCM is just like a muffler or hose clamp.
The rail itself is extremely stout because it’s a tube with the rails on it. The only thing that would really knock a zero off would be if it took a hard enough hit to make it squirm on the rail.
And in your opinion, a hit sufficiently hard to squirm the rail on the nut would be hard enough that you would consider it GTG with a PEQ?
I just discovered that the URX3 is still available. Anybody using one with full pic rail panels? How’s it feel/weigh? I missed out on that gen of KAC rails.
I’ll google around for more BCM reviews later, about to go shoot.
