Rail deflection with MFAL's.

[danieljmaunder]

So I'm building a gun specifically for IR and NVG use, got a lot of night hunts and pest control planned for this year. I'm familiar with the issue of rail deflection especially with MFAL,s and want a really solid rail to mount the laser on. Outside of going with a monolithic design, what is one of the best rails to use as a laser host? The Daniel Defense RIS 2's seem to do well but I'd prefer to go with something a little lighter. I've tested some of the rails I have laying around, for example a forward controls RHF I can put a half inch of flex with my thumb and index finger on the muzzle device. Looking for mlok rails if possible that won't have a crazy poa/poi shift. Has anyone had any experiencd with the centurion CMR rails? The ones I've handled seem to be a little thicker than most other mlok rails

[gunnerblue]

Larue followed by Geissele (original, MK 2, 4 AND 8) for minimal shift. I'm sure that there are others but these two are all that I've used. Or, like you said, there's always monolothic.

[danieljmaunder]

I'd love a monolithic like an LMT MRP but damn they're expensive. Just can't afford the whole thing versus upgrading the rail on my existing upper.

[Defaultmp3]

Older post:


Hey guys...hope all is well with all of you. I want to address rail and barrel deflection. First off in my observations, rail and barrel deflection can come from various sources. What is deflection, to me it's when a constant load is being placed on the rail, and how much it moves under a load. Why is deflection important to you....to me, it's in the use of aiming devices such as lasers etc. What causes deflection....here is where it gets sketchy....so your results may vary.

Type of fitment of rail onto barrel nut.
Type of barrel nut and how long, and how much bearing surface it has to the rail.
Upper receiver, how tight the barrel extension goes into the upper, concentricy of face of upper, threads, torque value, heat, demential mass in the upper, etc...can be variables.
Type of fitment between the lower and upper.

Basically if one were to test the "flexibility" in a rail not attached to a barrel/upper, you would not likely see much flexibility to make any real difference.

If you see barrel deflection under a rail load, it's the upper flexing via the threads the nut is attached to.

You have to ask yourself, what is important to you in the way you use your carbine, and how much difference does it really make? Not everyone runs lasers, not everyone loads a bipod, and will a sling and or a barricade effect you enough in a dynamic environment.

I have tested mine, as well as others, we did great, but yet there are others out there who did great as well.

There is no standardized testing that I know about... so yet another variable ��

DD, Geissele, KAC... I've used them all, and all with good results.

Cheers, Jim Hodge

I doubt that the Centurion Arms AR-15 handguards would do particularly well compared to others on the market when it comes to deflection, given the small size of the barrel nut, though this is purely a SWAG and not something I know for a fact. Quad rail handguards might be rigid as **** given all the material on them, but they can still deflect if their interface with the barrel nut gives them room to move.

My question is, what kind of shooting hunting are you doing while hunting? Handguard deflection (obligatory screed about how handguards are not the same as rails, handguards can have rails, but you can also have just rail sections, etc.) is a real thing, but if you're mostly shooting off hand, or with minimal pressure on the handguard, i.e., you're not bearing down on the handguard to form stability like one would with sling-assisted shooting, barricade shooting, or loading a bipod, then it probably doesn't matter very much. Just resting your handguard on something should have pretty minimal POA/POI shift. Beyond that, if you're not using the rifle in a duty manner, then it's not a big deal to simply mount the pointer much further back on the handguard, which will minimize perceived deflection.

Otherwise, I would suggest looking at the various Hodge designs (WedgeLock variant, P-Lock, S-Lock, Drive Lock), Geissele (the older models having better rigidity than the newer models, e.g., MK8 vs MK16), Daniel Defense RIS (the III is coming out soon, you could always wait for that), Ripcord Industries LDR1, Griffin Industries RIGID series, Midwest Industries Night Fighter, and KAC URX4. Not an exhaustive list, and I do not personally vouch for anything on this list, just models to consider (I use a Hodge WedgeLock on my 11.5" that is my night gun).

[vandal5]

No experience with them but how about one of these?

https://www.ripcordindustries.com/ldr-1

[danieljmaunder]

There will be a lot of bipod or offhand with sling shooting which is why I'm concerned about flex. I know the DD rails are freakin solid and I saw the RIS 3 is about to drop so I might be interested in that. Beyond that, this will double as a go to rifle for whatever hypothetical situation we can invent in our minds so I have duty thoughts in this as well and definitely want the laser mounted as far forward as possible. Plus I just hate having shadow in the illuminator.

[Defaultmp3]

There will be a lot of bipod or offhand with sling shooting which is why I'm concerned about flex. I know the DD rails are freakin solid and I saw the RIS 3 is about to drop so I might be interested in that. Beyond that, this will double as a go to rifle for whatever hypothetical situation we can invent in our minds so I have duty thoughts in this as well and definitely want the laser mounted as far forward as possible. Plus I just hate having shadow in the illuminator.With the force behind loading a bipod, you will likely see deflection with any non-monolithic handguard, particularly if it's a longer handguard. I would also be wary of any POA/POI shifts that can occur in such a situation, even without a pointer in the mix; a friend of mine was able to consistently generate several MOA worth of shift when he loaded the bipod on his KAC LPR. While stiffer handguards will have less deflection, that doesn't mean they will have no deflection; this is something that I was taught during my NODs class, the need to recognize when one was missing despite having a good sight picture and good trigger squeeze, and that deflection may be an issue, given the amount of force one can lever into a handguard, something that the instructor (Pressburg) had seen downrange.

I'm also mildly curious as to the use-case of regularly using a bipoded rifle with a pointer, rather than using a clip-on, if that level of precision will be needed.

[danieljmaunder]

Main reason for bipod use will be for some coyote stuff out of the bed of a truck, working on getting clip on sights but just dont have them yet. The bipod isn't as big of a concern as I'm well aware of how much force is generated when loading a bipod. But bracing off of a truck or using a sling to stabilize is what will be happening most of the time so I want to make sure that those forces aren't going to create a huge shift. The RIS 2 is probably the safest bet, as its proven and can double in a duty roll

[opngrnd]

The RHF handguard has much more shift than the DD and Geissele rails I've used. It's kind of like comparing the most flex to the least flex outside of going monolithic. The BCM rails also flex quite a bit. I'd take a good look at the available G and DD rails and go from there. Midwest Industries makes a series of rails for this application which you can find at the following link: https://www.midwestindustriesinc.com/Night-Fighter-Handguards-s/602.htm

[danieljmaunder]

Saw the nightfighter handguards and they look pretty good. You know anyone who's used them?

[opngrnd]

Saw the nightfighter handguards and they look pretty good. You know anyone who's used them?

I don't, but would like to try one.

[danieljmaunder]

I'm thinking about snagging one since the price is half what a DD is. If I get one I'll post back up and let you know

[opngrnd]

I'm thinking about snagging one since the price is half what a DD is. If I get one I'll post back up and let you know

Much appreciated. It definitely looks worth a try.

[prepare]

SOLGW M89

[xFREDx]

i don't think i can really add much to this post as i don't have NV so no experience with shift on lasers. I have done test with irons and of the handguards i have used (DD MFR MLOK, BCM QRF, BCM MCMR, Geissele MK8, Geissele Mk14, LT quad, LT LAT, a VLTOR Freedom MLOK). most were 13 or 13.5" but the MCMR was 15", the LAT was 12" and three MK8 (10.5, 13, and 13.5). top choices after zero then load on a bipod and shoot prone were both Larue's, MK8s, vltor freedom rail. next up was the QRF 12 and Mk14. last was the 15' MCMR. i still like the MCMR but that long rail did notice impact shift. I no longer have that handugard on that rifle and wish i did as i did a following test below (that is not scientific but caught my interest when i found the results).

take this with a grain of salt
at my local gun shop about 6 months ago, they had 3 identical rifles (in barrel length and handguard length) all were mlok
G super duty 16" barrel 15" mk16 handguard (surefire CTN)
BCM 16" BFH with 15" mcmr handguard (cant remember what comp it had but it was BCMs)
DD V7 16" barrel with 15" MFR mlok (DD's flash hider)
I took them down and with my thumb and index flinger tried to pinch the barrel to the handguard at the shoulder of the MD. not with much pressure as i didn't want to mess up any rifle. to my amazement the GMK16 rail i could almost get it to touch with very little pressure. it felt spongy at the connection with the upper, barrel and barrel nut. the other two i couldn't really budge them at all and i said that BCMs was the winner as i think i moved slightly less than the DD. but it took me several times to figure that out as it was close between those two. Something could of been wrong with that rifle and i kind of think there was.

[TMS951]

I have found the geissele mk8 to be very stiff and solid.

[themonk]

SOLGW, Hodge, KAC, LMT monolithic.

[Stickman]

Saw the nightfighter handguards and they look pretty good. You know anyone who's used them?

I've got one built onto an upper sitting about 10' away from me. There isn't much doubt it is a solid rail. That doesn't mean there aren't other solid rails, it simply means this one was designed for the task of which you speak.

[opngrnd]

I've got one built onto an upper sitting about 10' away from me. There isn't much doubt it is a solid rail. That doesn't mean there aren't other solid rails, it simply means this one was designed for the task of which you speak.

Great to know.

[1168]

Rails I have personal experience with and can recommend:

Picatinny: DDM4 and Larue. DDM4 is lighter and more expensive. I’m not sure if it could be used as a club or not, but neither of mine show much flex in normal use, or when finger-fooking them. I’ve got a 12” and a 10”. Larue is a brick shithouse and is what I’d most recommend for a Pic rail. Anything that makes it lose zero will kill the laser and/or user. I’ve got an 11”. Both of those rails have similar, but smaller profiles than the RISII (I own a 12”). The Centurion C4 has a very different profile, but is also good and will hold zero and flex very little. I use a middy FSB cutout one. I use 5 uppers with all 4 of these with a LAM and am happy with them. https://www.m4carbine.net/showthread.php?229872-Cheese-Graters-2021

MLok: Geissele Mk8 (thicc), KAC URX4 and Larue LAT (Goldilocks), Hodge, SOLGW, and Triarc Wedge-Lok (anorexic). Of these, the one I like most is the URX4. I’ve got a few of these, and one has been used extensively with LAMs. Its a 10.75”, but I’ve used or have every length but the 8.5”. Its probably the lightest handguard that I’d recommend for lasers. The Wedgelock is stout, but there’s not much to hold onto after you mount a light and laser. Dudes that use vert grips or have small hands will like them more than I do. I have a 7”, but it doesn’t really see much use. The G Mk16 handguards are fine on a 11.5” barrel, but skinny like a Wedgelok. I have too little experience with the longer ones to give much advice, but I have a buddy with a 16” Super Duty and a DBAL D2, and he’s happy. He shoots it weekly and its his main squeeze.

SBRs will show less flex than, say, a bipod gun with a skinny 15” handguard. I haven’t tried the new MI one.

[titsonritz]

A similar thread I made a couple months ago.
https://www.m4carbine.net/showthread.php?235037-Which-handguards-are-suitable-for-active-aiming-with-a-laser

[Biggy]

I use the KAC 10.75” rail for my 11.5” barreled upper, a 13” SOLGW M89 rail for my 14.5” barreled upper, a 15” SOLGW M89 rail on my 18” SPR upper. They are all very rigid rails/ handguards that have little flex. I think for my 12.5” barreled upper I am going to try the Ripcord Industries LDR1 11.75” handguard. IMHO, many things including the type of aluminum alloy can affect how rigid and how much flex a free float handguard has. I like to start with a reinforced upper like the BCM MK12 or the VLTOR MUR. I like barrels and uppers receivers that need to be thermally fit together and that have their receiver face lapped to ensure that it’s true. I like handguards that have extra long steel or titanium barrel nuts like the SOLGW, MI Nightfighter Series, Wedgelock, Ripcord Industries, etc. that have less heat transfer than aluminum barrel nuts. The barrel nut threads should be cut correctly and not be to sloppy when screwed onto the upper and have a nice snug fit with the handguard. From the type of aluminum alloy used, the extrusions finished wall thickness along with Mlok cut out placement all play a part in the handguards rigidity. I also like a handguards that have a little larger ID like the KAC URX4 or SOLGW M89, that give a little more clearance around the gas block and Mlok attachments.

ripcordindustries.com

[themonk]

I use the KAC 10.75” rail for my 11.5” barreled upper, a 13” SOLGW M89 rail for my 14.5” barreled upper, a 15” SOLGW M89 rail on my 18” SPR upper. They are all very rigid rails/ handguards that have little flex. I think for my 12.5” barreled upper I am going to try the Ripcord Industries LDR1 11.75” handguard. IMHO, many things can affect how rigid and how much flex a free float handguard has. I like to start with a reinforced upper like the BCM MK12 or the VLTOR MUR. I like barrels and uppers receivers that need to be thermally fit together and that have their receiver face lapped to ensure that it’s true. I like handguards that have extra long and strong steel or titanium barrel nuts that have less heat transfer than aluminum barrel nuts, like the SOLGW, MI Nightfighter Series, Wedgelock, Ripcord Industries, etc. The barrel nut should have a nice snug fit with the handguard. Rail wall thickness along with Mlok cut out placement also is a factor. I also like a handguards that have a little larger ID like the KAC URX4 or SOLGW M89, that give a little more clearance around the gas block and Mlok attachments.

https://r.search.yahoo.com/_ylt=Awr9DtUc.5his0wAgbBx.9w4;_ylu=Y29sbwNncTEEcG9zAzEEdnRpZANDT0NPTkVXUzAwMl8xBHNlYwNzcg--/RV=2/RE=1654221725/RO=10/RU=https%3a%2f%2fwww.ripcordindustries.com%2f/RK=2/RS=qgIBpnYQN7DAnhGCpcdzn.47hzY-

Thanks for the link

[Defaultmp3]

I will note that while the Ripcord Industries LDR1 is interesting and checks the right boxes for me to suggest looking at for a handguard for minimal deflection, the Nocturnality report/test is ****ing garbage. They only do n = 1, no statements as to how they assembled each AR (i.e., torque specs), and frankly a ridiculous method of testing that is highly reliant on shooters being consistent from string to string.

A far easier way would be to simply throw the uppers in a vise, zero a laser on a target, and then add weights on the handguard to see the deflection. Super repeatable, minimal human fallibility involved, doesn't even involve ammo. AFAIK, this is what DoD did when they were doing handguard deflection testing, or so I was told.

[Eurodriver]

Get a NOX35 Thermal scope - then you can get whatever rail you want.

[titsonritz]

Any one know if the Ripcord Handguard comes with an index pin/hole? I is not mentioned on their site like it was here on this article...

https://attackcopter.com/2021/07/01/ripcord-industries-goes-live-with-ldr1-rail-series/

[danieljmaunder]

Update, ended up going with a midwest industries nightfiter 13 inch handguard, so far so good. I'll be zeroing the laser soon so I'll post another update once I've played around with it. So far versus the geissele mk16 and forward controls rail I have, theres definitely a little less flex as far what I can put on pressure wise with my fingers. Barrel nut fit to upper receiver was excellent, threads were machined very nicely and a snug fit. Rail to barrel nut interface is very tight, took lots of wiggling to get it on. Also the machining as far as how they made the rail to keep it stuff, its freaking thick. They also kept the inside diameter small and didn't remove a lot of material. Outside diameter is on par with most other mlok rails on the market currently. Thanks again everyone for the suggestions and help!

[danieljmaunder]

Update on midwest nightfighter. So far its been amazingly good to go. Laser zeroed, did some night shooting while slung and barricaded, shots made out to about 125 yards. With my 6'5 250 lb self leaning hard against the rail stacked up against the barricade it was ringing steel all night. For the price point compared to some of the other NVG designed rails, I think its a good buy. For reference, the laser used was an atpial, 13.5 nightfighter handguard mounted on a colt 14.5 upper.