View Full Version : Durability of slick rails
bowman57_2
10-12-16, 23:35
This is probably kind of a stupid question but its been in my head for atleast the last 2 years. How durable are slick sided rails? I'm not talking about the different mounting systems/the rail being knocked off center, I'm talking about the rails being dented or bent. I've been wondering how much of a difference the shape of a rail can affect the strength/integrity of it, like I would imagine (and could be wrong) a rail like the DD SLiM with a cross-like shape would take more force to dent than a mostly round rail like a Troy Alpha or something. Could something like a CMR survive years of military use, or will it always be left up to a quad rail for that kind of hard use? I've just always been curious what kind of beating these things could take, so what do you guys think?
There is a huge variation among slick rails. One end there is the aluminum/magnesium KMR which I have caused to lose zero with firm smacks from my support hand (sorry to report) or the MI rail which has been reported to come off the barrel nut. On the other hand there is the Mega/Hodge Wedge rail which I would feel comfortable driving my car over if I did not want to ruin the finish or the Geissele MK8 which is a cousin of the HK416 rail. I have not yet used a CMR but the older ones are reported to be very durable.
I have never had any sort of military deployment but I cannot imagine anyone not being well served in "hard use" by a Geissele MK8 or Mega/Hodge Wedge. They are both incredibly strong and well built.
My Hodge rail is built like a tank.
elephantrider
10-13-16, 05:29
I would then to think that rails with an 'I-beam' type shape (Mk 8, DD Slim) would be stronger just based on their basic shape. So many other factors also come into play on the design (wall thickness, alloy type, tube diameter) and destructive force (type of impact or force put on the rail) that it's hard to definitively say without just smashing up a bunch of rails. OP, you say to discount the barrel nut/mounting system as part of the 'durability' question, but a stronger lock-up at the barrel nut may also play a part in over robustness. Probably not coincidence that the rails with a better lock-up at the barrel nut then to be more stout overall.
Brick shit house class rails:
Geissele SMR series (Mk 8, Mk4, etc)
Hodge/Mega Wedge Lock rails
Pretty darn tough:
ALG defense EMR
- a bunch of other rails, I've not had my hands on yet
I would then to think that rails with an 'I-beam' type shape (Mk 8, DD Slim) would be stronger just based on their basic shape.
There is a reason NASCAR cars use round tubing instead of I beam or plus sign shaped extrusions.
The non-cylindrical shapes have to be much thicker (and heavier) to get similar rigidity/strength.
I'm sure you could crush a tube type extrusion, but for equal weight they are very strong
There is a reason NASCAR cars use round tubing instead of I beam or plus sign shaped extrusions.
The non-cylindrical shapes have to be much thicker (and heavier) to get similar rigidity/strength.
I'm sure you could crush a tube type extrusion, but for equal weight they are very strong
This.
My professional background is in structural design. Tubes & Pipes are quite strong, especially when compared to "I-Beam" (W shape) sections.
Regardless, Aluminum Handguards do not see forces strong enough to favor one shape over another. Where odd shapes may lack structural integrity, it can be made up with wall thickness.
PapaFoxtrot
10-13-16, 08:19
One of my 16" mids with a BCM mag alloy 13" KMR was knocked off a 48" high rifle rack onto a concrete slab.
Among a few other bruises all around, a front corner of the rail was dented/gouged, the finish was easily scratched, and the buis lost zero. I am not inclined to measure it for deflection/loss of concentricity, but I certainly think it was bent slightly. (FYI the Aimpoint maintained zero and brushed it off like nothing happened.) Maybe that rifle is unlucky, so if it gets run over, I will report back.
I also have a DD 12" SLiM, and agree that it is a much tougher "tube" than the BCM KMR, regardless of which cross section might be the more rigid in design theory.
OTOH, I have ALG EMRs that I think are very durable due to the rigid tube design and superb nut and attachment to the nut. Great balance of slim and strong, with M-LOK. No more KMR for me, ever.
As far as total overkill heavy duty quad rails go, I have long since removed and changed them all, having accepted the weight reduction, slim profile, and rail-only-where-desired as good compromises. I don't want to carry the weight of something that is indestructible, but of course want the most strength at a given acceptable weight. And "too light" is possible.
bowman57_2
10-13-16, 08:59
This.
My professional background is in structural design. Tubes & Pipes are quite strong, especially when compared to "I-Beam" (W shape) sections.
Regardless, Aluminum Handguards do not see forces strong enough to favor one shape over another. Where odd shapes may lack structural integrity, it can be made up with wall thickness.
What about rails with internal ribs like the Griffin Rigid Rail? How much does that help keep a rail from denting/benting?
bowman57_2
10-13-16, 09:05
No more KMR for me, ever.
I've thought the same thing about the KMR since it originally came out, its just way too light and thin to take a very hard hit IMO. I think its great for precision guns but I dont like it for a go to carbine.
My Hodge rail is built like a tank.
Did you use the anti-rotation pin?
556BlackRifle
10-13-16, 09:50
In my experience the Noveske NSR is a tough slick rail. Not to say that it couldn't be dinged, dented or crushed if enough force was applied. It is definitely more robust than the original KMR - I have no experience with the KMR Alpha so I'll let someone else speak to that.
This is the trade off. When you cut weight, you cut rigidity. In knockdown drag out combat, I'd rather have more mass / rigidity, but when it comes to civilian / LEO TAC-OPs I think the NSR would be a good choice. Reality check; My go to HD rifle is running an SMR MK8-13.
bowman57_2
10-13-16, 10:08
I have not yet used a CMR but the older ones are reported to be very durable.
This is the kinda of stuff im interested in, why would the original be more rugged than the new mlok model?
Defaultmp3
10-13-16, 10:20
This is the kinda of stuff im interested in, why would the original be more rugged than the new mlok model?Well, the Gen1s didn't have any lightening cuts or anything, it was mostly solid:
https://4b1e874935ea5d25a97e-f099844d0e354c7ab50c55a966be6870.ssl.cf2.rackcdn.com/product/XCENT01114.jpg
The Gen 2s have the lightening cuts, and I'm told some of the reinforcement ribs on the inside were shrunk down for greater gas block compatibility (the barrel nut was also altered for easier installment):
http://cdn3.volusion.com/xjhfl.toyeo/v/vspfiles/photos/01114-3.jpg
The M-LOK also has a lot more holes, and I'd assume also has the reduced ribs:
https://www.rainierarms.com/media/product/5f9/centurion-arms-5-56-cmr-m-lok-13-ml1513-by-centurion-arms-9f6.jpg
What about rails with internal ribs like the Griffin Rigid Rail? How much does that help keep a rail from denting/benting?
Internal ribs increase strength in any bend. Although I have not tested the Rigid rail yet, I do plan on ordering one in the near future. From a structural design standpoint, it is superior to similarly priced rails out there (Geissele & BCM). The most vulnerable area of any handguard is the exposed end. This is where you are most likely to experience denting or marring. It's something that is damn near impossible to prevent.
The biggest downfall of the BCM KMR is that they took a tube and milled flats. With ever flat they mill, they lose wall thickness and create weak points. Now I'm not bashing a KMR, as they are extremely popular and they are indeed lightweight, but in terms of strength they lack structural integrity.
This.
My professional background is in structural design. Tubes & Pipes are quite strong, especially when compared to "I-Beam" (W shape) sections.
Regardless, Aluminum Handguards do not see forces strong enough to favor one shape over another. Where odd shapes may lack structural integrity, it can be made up with wall thickness.
Beat me too it. Odd shapes can be stronger in a particular loading direction, but at the trade off of being weaker in other directions. Great for structural efficiency in applications where the loads are well known and repeatable, like floor beams, aircraft stringers, etc etc. For something the loads are variable and/or not well defined, a tube is a good choice. More so when the chances of hitting an ultimate load is slim.....
Beat me too it. Odd shapes can be stronger in a particular loading direction, but at the trade off of being weaker in other directions. Great for structural efficiency in applications where the loads are well known and repeatable, like floor beams, aircraft stringers, etc etc. For something the loads are variable and/or not well defined, a tube is a good choice. More so when the chances of hitting an ultimate load is slim.....
Bingo.
Handguards are designed to Guard your Hand and have the luxury to mount accessories. While strength is definitely a concern, I highly doubt any company designs a handguard to be able to withstand the shock of being dropped off a building. Furthermore, they would not sacrifice key features for added piece of mind.
Internal ribs increase strength in any bend.
100% yes again. It's ridiculous what you can do with stiffening ribs. WAAAAAY back in my Sr year of college we had to design/optimize stiffened AL panels to hold a 1500lb load. Winning design was the one that got closest to the 1500lb weight with positive margin, netting the team a nice dinner at the professors expense. We didn't win but our panel weighed 4.37lbs and held up a load of 1550lbs. That's with the outer AL skin only being 0.065 2026-T6.....
Ive been incredibly impressed with the DD LITE III rail. Half my uppers now sport these rails. They are very robust, both in rail design and bolt up mechanism. Also, when weighing otherwise identically outfitted uppers, my BCM middy w/ KMR-A is only about 3.5 oz. lighter than my BCM middy w/ DD LITE III. Not a huge difference when you consider what you are getting in return. I hate to be the guy who is always tooting the DD LITE III horn, but i feel like it's a viable option that some would enjoy, but have overlooked.
bowman57_2
10-13-16, 11:26
100% yes again. It's ridiculous what you can do with stiffening ribs.
I have always thought they would increase the rigidity/stiffness of a rail by a pretty good amount. Why don't more companies do this if its so helpful and adds very minimal weight and zero bulk to the rail. The only downside i could think of would be gas block clearance.
I have always thought they would increase the rigidity/stiffness of a rail by a pretty good amount. Why don't more companies do this if its so helpful and adds very minimal weight and zero bulk to the rail. The only downside i could think of would be gas block clearance.
1. Cost
2. Time
3. Weight
It costs more money to spend more time machining ribs that will ultimately weigh more.
There are not many manufacturers that advertise to be the strongest, but there are plenty that advertise to be the lightest.
Meh. I've dropped a KMR (space alloy version, NOT Alpha) equipped rifle 2x from ~30' onto hard ground with no ill effects.
That's good enough for me.
That's good enough for me.
Which is ultimately my point.
AR15 Handguards are not meant to hold up a bridge. While a KMR may not be the strongest, it's plenty strong for the intended purpose.
Which is ultimately my point.
AR15 Handguards are not meant to hold up a bridge. While a KMR may not be the strongest, it's plenty strong for the intended purpose.
Thinking a little further, lets say you did make a super strong rail. Say make it out of 4140 Steel or something like that. Big and beefy. Well, you've got to consider the whole system in design. You make the rail that strong, then hit it with a good whack, you reach a point where you risk damaging the upper receiver. It's only 7075 AL after all. In the grand scheme is it better to break your rail or your receiver?
1. Cost
2. Time
3. Weight
It costs more money to spend more time machining ribs that will ultimately weigh more.
There are not many manufacturers that advertise to be the strongest, but there are plenty that advertise to be the lightest.
The only way it would really make sense is if you went with a really thin wall thickness on the main body of the rail. If you went with a stiffened thin wall tube, you might, stress might, be able to build something more structurally efficient and lighter for equivalent strength. I wouldn't hang my hat on that design working as intended though....
bowman57_2
10-13-16, 12:42
This thread has answered alot of my questions and honnestly made me think about the durability of a rail differently, but I'm still interested in what else you guys have to say about it.
Thinking a little further, lets say you did make a super strong rail. Say make it out of 4140 Steel or something like that. Big and beefy. Well, you've got to consider the whole system in design. You make the rail that strong, then hit it with a good whack, you reach a point where you risk damaging the upper receiver. It's only 7075 AL after all. In the grand scheme is it better to break your rail or your receiver?
I agree, but God forbid we start that discussion LOL
Just remember kids, it always finds the path of least resistance.
This thread has answered alot of my questions and honnestly made me think about the durability of a rail differently, but I'm still interested in what else you guys have to say about it.
Buy quality, that's all you need to know.
BCM KMR's are quality and BCM has great CS.
ALG Defense/Geissele are also quality and has great CS.
If I ever buy a Griffin Armament Rigid, I will post a review.
titsonritz
10-13-16, 14:32
This.
My professional background is in structural design. Tubes & Pipes are quite strong, especially when compared to "I-Beam" (W shape) sections.
Mine too so I am going to say, yes and no. Tubes and pipes are more consistently strong in all directions, while wide flange and channels shapes the strength is directional, as in the direction of the web. That is why you see wide flange girders and joists but no so many tubes, pipes, HSS, etc. but I'm sure you know that.
bowman57_2
10-13-16, 14:36
Buy quality, that's all you need to know.
BCM KMR's are quality and BCM has great CS.
ALG Defense/Geissele are also quality and has great CS.
I've been going back and forth between a EMR V2, Griffin Rigid, and MLOK CMR for a while now, but I think im gonna go the Griffin route on this one.
I think it's safe to say the urx 4 is a durable design as well.
elephantrider
10-13-16, 17:57
Which is ultimately my point.
AR15 Handguards are not meant to hold up a bridge.
Nope, they are not. When assessing the durability of a handguard/rail you need to think about the forces that could potentially damage them (impact, crushing, etc) and which they are most likely to encounter. IMO this is impacts from a hard fall, or being accidentally swung into a hard obstacle (wall, car, light pole, etc.). If they are not deformed from direct impacts, what about impacts to hard mounted accessories? I would think that probably the easiest, and likeliest, way to deform or damage a rail would be from impacts to a solidly mounted flashlight.
While a KMR may not be the strongest, it's plenty strong for the intended purpose.
I think where the KMR may fall down is in my scenario described above. Mount a flashlight to one of the sides (not the top pic rail) and give it a good bash. My guess is that the rail walls bend in fairly easily. Just a guess, and maybe many similar rails would suffer the same fate, so not just knocking the KMR.
While a KMR may not be the strongest, it's plenty strong for the intended purpose.
This depends upon the intended purposes. Mine are as follows:
1. Protect the gas tube
2. Allow extended grip
3. Mount flashlight (12:00 on the KMR uppers)
4. Mount QD sling attachment point
5. Free float for accuracy and bolt life benefits
6. Mount BUIS that will maintain the information of the zero for cross-check against red dot, and to back up main optic should it ever fail
7. Mount IR laser (certain situations- my KMR uppers generally not intended for this because I do not really trust KMR keymods for the white light)
8. Mount bipod
When the KMR came out I bought the hype and ended up with four of them. They are very light and feel great in the hand. After using them for a significant period I can confirm that they do an admirable job of fulfilling criteria 1-5. Unfortunately, they failed for me at no.6. Some people might not care but for me this is a critical point. Two of the KMR's that had BUIS on them lost zero. The third upper never left the safe and the fourth was a precision upper without BUIS. The KMR on that one came off due to flyers with the bipod.
At first I told myself that I must not have zero'd the BUIS correctly in the first place. When it happened again on the same uppers after I made it a point to check the zeros I knew there was a problem so I started to do some personal testing. I found that I was sometimes able to move the BUIS zero with firm smacks to the 9:00 or 3:00 position of the rail. While this is clearly not rigorous scientific study, it moved me enough to make a change. The loss of zero did not happen all the time, but enough where I decided they all have to go. I have had two NSR uppers for going on four years which actually get shot a lot more. Neither has ever lost zero, and they will not lose zero with the support hand strikes.
If you only feel that criteria 1-5 are important and are weight sensitive, then the original KMR is probably "the" rail for you. If you feel that maintaining the information of the zero in the BUIS is important then I would recommend something heavier. I love BCM and invested over $1000 in these rails, but the problems I have experienced are real enough to cut my losses and move on to something else.
Did you use the anti-rotation pin?
I will when the rifle is complete. It's sitting in the safe for now.
I will when the rifle is complete. It's sitting in the safe for now.
Which upper are you using?
Which upper are you using?
I'll post pix when it's complete. I really don't wish to share more currently, as I can't review a whole, piecemeal. I can say though that the rail is beefy yet light.
I'll post pix when it's complete. I really don't wish to share more currently, as I can't review a whole, piecemeal. I can say though that the rail is beefy yet light.
I have the 11.75, but I need to get my upper drilled for the anti-rotation pin. That's why I'm asking.
I have the 11.75, but I need to get my upper drilled for the anti-rotation pin. That's why I'm asking.
Ah, my answer wouldn't be of any help. The upper I am using is not available at this time, hence the project not being finished.
I've broken a lot of AR sh1t... sights, mounts, etc. And I've beaten the O.G. KMRs pretty good with no complaints. Nothing is completely bullet proof. But of the light hand guards, I've not seen any totally weak failures.
SO's rifle has a KMR-a, and that rifle hasn't exactly led a comfy life, it's taken a number of tumbles, and is still perfectly functional.
Sample of 1 though...
praythenspray
10-14-16, 07:20
So this was with the original KMR rail. I am curious to what length it was. From what I have read(and anyone chime in if I am wrong) if there were to be any trouble with the rails in the manner you have described, it is with the long 15"(possibly 13"?) versions.
This depends upon the intended purposes. Mine are as follows:
1. Protect the gas tube
2. Allow extended grip
3. Mount flashlight (12:00 on the KMR uppers)
4. Mount QD sling attachment point
5. Free float for accuracy and bolt life benefits
6. Mount BUIS that will maintain the information of the zero for cross-check against red dot, and to back up main optic should it ever fail
7. Mount IR laser (certain situations- my KMR uppers generally not intended for this because I do not really trust KMR keymods for the white light)
8. Mount bipod
When the KMR came out I bought the hype and ended up with four of them. They are very light and feel great in the hand. After using them for a significant period I can confirm that they do an admirable job of fulfilling criteria 1-5. Unfortunately, they failed for me at no.6. Some people might not care but for me this is a critical point. Two of the KMR's that had BUIS on them lost zero. The third upper never left the safe and the fourth was a precision upper without BUIS. The KMR on that one came off due to flyers with the bipod.
At first I told myself that I must not have zero'd the BUIS correctly in the first place. When it happened again on the same uppers after I made it a point to check the zeros I knew there was a problem so I started to do some personal testing. I found that I was sometimes able to move the BUIS zero with firm smacks to the 9:00 or 3:00 position of the rail. While this is clearly not rigorous scientific study, it moved me enough to make a change. The loss of zero did not happen all the time, but enough where I decided they all have to go. I have had two NSR uppers for going on four years which actually get shot a lot more. Neither has ever lost zero, and they will not lose zero with the support hand strikes.
If you only feel that criteria 1-5 are important and are weight sensitive, then the original KMR is probably "the" rail for you. If you feel that maintaining the information of the zero in the BUIS is important then I would recommend something heavier. I love BCM and invested over $1000 in these rails, but the problems I have experienced are real enough to cut my losses and move on to something else.
One was 13 the other was 10. The 13 is was a factory built upper.
elephantrider
10-14-16, 17:30
There is a reason NASCAR cars use round tubing instead of I beam or plus sign shaped extrusions.
The non-cylindrical shapes have to be much thicker (and heavier) to get similar rigidity/strength.
I'm sure you could crush a tube type extrusion, but for equal weight they are very strong
Tension/compression not shear and bending. Different forces, different application. You also left out my next sentence with some qualifiers.
elephantrider
10-14-16, 17:58
Internal ribs increase strength in any bend. Although I have not tested the Rigid rail yet, I do plan on ordering one in the near future. From a structural design standpoint, it is superior to similarly priced rails out there (Geissele & BCM).
Uhhh, how is it superior if it isn't released or tested yet?
The most vulnerable area of any handguard is the exposed end. This is where you are most likely to experience denting or marring. It's something that is damn near impossible to prevent.
You should check with Will from Arisaka Defense (Slippers). He has essentially informally tested this when testing their light mounts.
Uhhh, how is it superior if it isn't released or tested yet?
You should check with Will from Arisaka Defense (Slippers). He has essentially informally tested this when testing their light mounts.
If what isn't released yet? You can buy a Rigid Rail directly from Griffin Armament.
Also note that I'm speaking in generalities about structural design. I never said it's a superior handguard.
elephantrider
10-14-16, 18:11
1. Cost
2. Time
3. Weight
It costs more money to spend more time machining ribs that will ultimately weigh more.
There are not many manufacturers that advertise to be the strongest, but there are plenty that advertise to be the lightest.
Extrusions. There are a few inexpensive rails with internal ribs.
Extrusions. There are a few inexpensive rails with internal ribs.
Extrusions are a different subject altogether.
elephantrider
10-14-16, 20:39
Extrusions are a different subject altogether.
Huh? ALG EMR. Affordable rail, with interior ribs, machined from and extrusion.
ETA: I may have read that wrong. They may just be entirely machined from extruded material. Either way, affordable rail with interior ribs. Not that expensive to mfg.
Tension/compression not shear and bending. Different forces, different application. You also left out my next sentence with some qualifiers.
And torsion and random torque/bending loads. I beams and similar engineered shapes are great for specific load directions. But not any arbitrary direction, tubes/cylinders still win that for a given weight.
elephantrider
10-14-16, 23:02
And torsion and random torque/bending loads. I beams and similar engineered shapes are great for specific load directions. But not any arbitrary direction, tubes/cylinders still win that for a given weight.
You keep comparing a tube to an I-beam, or plus section. Although I referenced 'I-beam' in my original post, that really isn't a good term for what we are talking about here. It is more of a tube vs. a modified tube shape situation.
You keep comparing a tube to an I-beam, or plus section. Although I referenced 'I-beam' in my original post, that really isn't a good term for what we are talking about here. It is more of a tube vs. a modified tube shape situation.
Cylindrical Tubes or Square Tubes? Modified tubes? We can debate semantics all day.
What is your professional background, if you don't mind me asking?
A round tube will be the most uniformly strong to various forces. I have no degree in structural understandings. Just common sense analysis of geometry shows it to be logically sound.
Cylindrical Tubes or Square Tubes? Modified tubes? We can debate semantics all day.
What is your professional background, if you don't mind me asking?
it kinda is semantics. when you break it down all handguards are tubes. they have to be for the barrel. it's just a matter of the cross section.
round beam, box beam, etc etc. that cross section determines how well the beam can carry a load in any particular direction.
Sent from my SAMSUNG-SM-G930A using Tapatalk
I remember my first structural engineering class (25 years ago). The professor rolled up a sheet of paper into a "tube shape" and placed the 3" thick Allowable Stress Design manual on top of it. This simple demonstration was to show the strength of the cylindrical shape to non-axial loads. Once he "squeezed" the "column", it failed, and the book fell. I'm not really sure how this applies here though, but thought it was an interesting anecdote.
Anyway, I've used various aluminum rail and handguard profiles and haven't had a structural problem with any of them. The rails I've used include: Troy MRF; Troy MRF-DI (carbine and mid); DD Slim Rail; DD Modular Float Rail; DD Omega; DD Lite Rail III; PSA LW Keymod; KAC RAS; Centurion C4 12"; Centurion MidLength Cut Out; YHM SLK, KAC URXII, etc.
I currently have: Centurion C4; DD LR III; DD Slim Rail; KAC RAS; and YHM SLK.
The only problem I've had was "out of spec" Troy's where I couldn't beat on slide on accessories with a rubber mallet. Stacking dimensional tolerance issues (between Tango Down accessories and the Troy rails) made them a no go. This was back when BCM first sold lowers and uppers. I bought two completed BFH mid lengths and added MRF-DI rails.
ETA: I'm just a civy who likes to shoot so my guns haven't been subjected to type of abuse .mil weapons endure.
And torsion and random torque/bending loads. I beams and similar engineered shapes are great for specific load directions. But not any arbitrary direction, tubes/cylinders still win that for a given weight.
Correct.
Wide flanges are never used in the Y direction for this reason. If connections to cylindrical shapes were easier - you wouldn't have TS (square tube) structural members. However, making moment connections, etc is nearly impossible with cyl so the TS and W exist.
How does this apply to slick handguards? I'm not sure it does. We're all discussing 36 or 50 KSI steel used in STATIC (live load is basically calculated as static in buildings) and predictable loading. The bending moment, and IMPACT RESISTANCE of various aluminum, fabrication methods, etc in which a rifle's handguard is subjected is what I'd call Statically Indeterminate.
...DM...before you ask....I am a licensed (multiple state) design professional with 20 years of post grad experience.
ETA: Arch (screen name) is short for Architect. I'm obviously more technical than your average black beret and gold medallion wearing architect.
gah someone who likes structural analysis. you fellas ain't right [emoji14]
Sent from my SAMSUNG-SM-G930A using Tapatalk
elephantrider
10-15-16, 14:44
Cylindrical Tubes or Square Tubes? Modified tubes? We can debate semantics all day.
What is your professional background, if you don't mind me asking?
You missed the point.
gah someone who likes structural analysis. you fellas ain't right [emoji14]
Sent from my SAMSUNG-SM-G930A using Tapatalk
hahaha
Just throwing this out there but what the world really needs is rails made of carbon nanotubes.
bowman57_2
10-15-16, 15:55
Just throwing this out there but what the world really needs is rails made of carbon nanotubes.
I dont know how much weight it would save or if someone already makes it, but i always thought it would be cool if someone made a light mount out of the same material as the original KMR.
Just throwing this out there but what the world really needs is rails made of carbon nanotubes.
I was thinking unicorn cytoskeletal polymers.
Fatorangecat
10-15-16, 17:12
How epic does a hand guard really have to be? It protects your gas block, gives you something to hold and you mount stuff to it.....
How epic does a hand guard really have to be? It protects your gas block, gives you something to hold and you mount stuff to it.....
It does more than that.
Sent from my iPhone using Tapatalk
PapaFoxtrot
10-15-16, 18:28
How epic does a hand guard really have to be? It protects your gas block, gives you something to hold and you mount stuff to it.....
It does more than that.
Yes, it certainly does in my case.
To some it might not matter, but that rail is a substitution for a front sight base that was integral with the gas block, and that was pinned rigidly to the barrel.
Optics aside, the rail will hold 50% of my bore axis indication system, which is the front BUIS. The term "back up" may have possibly relegated these folding sights to a status of lesser importance than they really hold.
By their severley cantilevered design, the front BUIS on a rail will deflect much more than a FSB iron sight, but I would like as little movement as possible.
Outlander Systems
10-15-16, 18:53
You assholes are overthinking it.
Jpmuscle and Scooter22 FTMFW.
Eurodriver
10-15-16, 19:01
You assholes are overthinking it.
Jpmuscle and Scooter22 FTMFW.
Yeah, that.
See sig.
elephantrider
10-15-16, 19:14
How epic does a hand guard really have to be? It protects your gas block, gives you something to hold and you mount stuff to it.....
Some folks need them to do all those you things listed, AND hold zero on rail mounted lasers and BUIS, while being subjected to a bit of rough handling and bumps, AND not be bent, smashed, or deformed to the point that they not longer work for the fore-mentioned tasks. I don't consider that "epic," rather a part that gets the job done.
Eurodriver
10-15-16, 19:48
How many people in this thread have IR lasers and use them in challenging conditions? Such as (and this is a totally random scenario) hurricanes?
How many people in this thread have IR lasers and use them in challenging conditions? Such as (and this is a totally random scenario) hurricanes?
Does Parasail count on Battlefield 4?
Seriously though, I see no issue with people who want the best, quality gear. Those people are the same who are responsible for our warriors in the gwot getting the tip of the edge in gear. If you note, socom trailed 3gun on nearly all of the firearm advancements. So I have nothing I'll to say of a dirtshooter looking for better kit!
I'm gonna start a company to make handguards starting with these for yall hope it's heavy duty enough lol...
http://uploads.tapatalk-cdn.com/20161016/8bde4005925c4c4c400b16ec86521e6e.jpg
Sent from my SAMSUNG-SM-G930A using Tapatalk
Eurodriver
10-15-16, 20:06
Does Parasail count on Battlefield 4?
Seriously though, I see no issue with people who want the best, quality gear. Those people are the same who are responsible for our warriors in the gwot getting the tip of the edge in gear. If you note, socom trailed 3gun on nearly all of the firearm advancements. So I have nothing I'll to say of a dirtshooter looking for better kit!
Of course everyone can, and should, have the best gear they desire. I also agree that 3 gun brings to the gun fighting community a particular asset that is unique and beneficial. No one questions that, I don't think.
The points being made by several people are that any quality rail on the market today will suffice for nearly all use in which a "slick rail" is intended and if people actually shot the gun instead of talking about 25 year old NASCAR roll cage strength physics they would realize that.
I mean, Markm breaks everything. But even he hasn't broken a rail.
Of course everyone can, and should, have the best gear they desire. I also agree that 3 gun brings to the gun fighting community a particular asset that is unique and beneficial. No one questions that, I don't think.
The points being made by several people are that any quality rail on the market today will suffice for nearly all use in which a "slick rail" is intended and if people actually shot the gun instead of talking about 25 year old NASCAR roll cage strength physics they would realize that.
I mean, Markm breaks everything. But even he hasn't broken a rail.
...that he will admit to.
Seriously, I don't think anyone is wringing their hands, we are just discussing making something mo betta!
elephantrider
10-15-16, 21:41
You assholes are overthinking it.
Jpmuscle and Scooter22 FTMFW.
How many people in this thread have IR lasers and use them in challenging conditions? Such as (and this is a totally random scenario) hurricanes?
I'm gonna start a company to make handguards starting with these for yall hope it's heavy duty enough lol...
^ Why the assumptions that this discussion is implying that currently available products are lacking?
Of course everyone can, and should, have the best gear they desire. I also agree that 3 gun brings to the gun fighting community a particular asset that is unique and beneficial. No one questions that, I don't think.
The points being made by several people are that any quality rail on the market today will suffice for nearly all use in which a "slick rail" is intended and if people actually shot the gun instead of talking about 25 year old NASCAR roll cage strength physics they would realize that.
I mean, Markm breaks everything. But even he hasn't broken a rail.
^ All true. There are rails/handguards that will fits most needs at price points from $125-$300 . The higher price points do not necessarily mean better for certain uses. I think a lot of buyers have a hard time understanding what they are getting with a particular product/price point.
Fatorangecat
10-15-16, 22:15
My comment was meant to be facetious. A hand guard is a rigid extension of the upper and anybody that has ever loaded a bipod gets that. A round tube or a square tube made from good material with a well designed barrel nut will suffice. You all treat hand guards like women's fashion .....OMG! the quad rail is so 90s, I wouldn't be caught dead with one.
elephantrider
10-16-16, 00:43
My comment was meant to be facetious.
Was it?
A hand guard is a rigid extension of the upper and anybody that has ever loaded a bipod gets that.
No, many will flex quite a bit.
You all treat hand guards like women's fashion .....OMG! the quad rail is so 90s, I wouldn't be caught dead with one.
So, are you being facetious again? Or are you being serious, because this thread is not about Quad, vs slick rail.
^ Why the assumptions that this discussion is implying that currently available products are lacking?
^ All true. There are rails/handguards that will fits most needs at price points from $125-$300 . The higher price points do not necessarily mean better for certain uses. I think a lot of buyers have a hard time understanding what they are getting with a particular product/price point.
no assumption on my part. I was just fooling around
Sent from my SAMSUNG-SM-G930A using Tapatalk
Correct.
Wide flanges are never used in the Y direction for this reason. If connections to cylindrical shapes were easier - you wouldn't have TS (square tube) structural members. However, making moment connections, etc is nearly impossible with cyl so the TS and W exist.
How does this apply to slick handguards? I'm not sure it does. We're all discussing 36 or 50 KSI steel used in STATIC (live load is basically calculated as static in buildings) and predictable loading. The bending moment, and IMPACT RESISTANCE of various aluminum, fabrication methods, etc in which a rifle's handguard is subjected is what I'd call Statically Indeterminate.
...DM...before you ask....I am a licensed (multiple state) design professional with 20 years of post grad experience.
ETA: Arch (screen name) is short for Architect. I'm obviously more technical than your average black beret and gold medallion wearing architect.
Thanks for commenting, your input is much appreciated. Although it is unnecessary to state it, I'm sure each manufacturer does their own load testing to each handguard. They would be stupid not to.
You missed the point.
I got your point, but I chose not to feed you.
elephantrider
10-16-16, 16:02
I got your point, but I chose not to feed you.
Maybe don't respond at all then?
This thread sucks. If you've had an experience with free float rails being damaged or losing zero, post it. I've got a 13" kmr with DD aluminum fixed sights, always shoots like a laser.
Eta: I 2 point sling with the mount far forward as possible and really sling up tight. No deflection problems for me.
OK kids. Before this turns into Orange Hair vs. Pant Suits let's try and be productive and nice.
I can tell you the nsr rail is weak and didn't survive a two foot drop that caught a closed bipod. They also wouldn't replace it.
http://i101.photobucket.com/albums/m61/proto19/654D0B17-E959-4D4C-A655-22EA23616A86.jpg (http://s101.photobucket.com/user/proto19/media/654D0B17-E959-4D4C-A655-22EA23616A86.jpg.html)
http://i101.photobucket.com/albums/m61/proto19/E5080597-1F3A-4612-8583-EB2D04CAE66E.jpg (http://s101.photobucket.com/user/proto19/media/E5080597-1F3A-4612-8583-EB2D04CAE66E.jpg.html)
Nocalsocal
10-18-16, 00:23
I just picked up a SMOS SM13 rail and subjectively it feels alot more robust than my KMR rails. According to SMOS the difference between the SM line vs the GFY rail is the greater rigidity and subsequent increase in weight and thickness . After seeing the above NSR, I'm glad I went with the stronger rail. Especially since the design is very similar between the two lightweight rails.
Sent from my SM-G935V using Tapatalk
bowman57_2
10-18-16, 11:04
http://i101.photobucket.com/albums/m61/proto19/654D0B17-E959-4D4C-A655-22EA23616A86.jpg (http://s101.photobucket.com/user/proto19/media/654D0B17-E959-4D4C-A655-22EA23616A86.jpg.html)
This is what I picture every time I think of a slick rail taking a good spill.
But did it loose zero? That is IMO the most important question. If it's just a deformation of the lower half I'd call that a win, even if having to replace it sucks
But did it loose zero?
When I read that, this immediately popped into my mind, with a sarcastically-optimistic Asian voice:
https://i.imgflip.com/1ck7l5.jpg
Sorry - carry on :)
bowman57_2
10-18-16, 13:41
Pictures like that just dont instill confidence when youre looking at speending $200-$300 on a rail. I kinda expect it to hold up if it takes a 2 foot fall.
Pictures like that just dont instill confidence when youre looking at speending $200-$300 on a rail. I kinda expect it to hold up if it takes a 2 foot fall.
Exactly. I spoke with Mike at SOLGW and he/ they are going to toss one of their rails on for me.
But did it loose zero? That is IMO the most important question. If it's just a deformation of the lower half I'd call that a win, even if having to replace it sucks
Yes. The top is tweaked as well. This weak of an impact should've been warrantied. No more Noveske or keymod for me.
This is what I picture every time I think of a slick rail taking a good spill.
This wasn't even a good spill.
Especially since the design is very similar between the two lightweight rails.
That's because SMOS used to machine the NSR rails.
When I read that, this immediately popped into my mind, with a sarcastically-optimistic Asian voice:
https://i.imgflip.com/1ck7l5.jpg
Sorry - carry on :)
3 internet points to you good sir
So it's back to quad rails again? :D
556BlackRifle
10-19-16, 01:27
I can tell you the nsr rail is weak and didn't survive a two foot drop that caught a closed bipod. They also wouldn't replace it.
http://i101.photobucket.com/albums/m61/proto19/654D0B17-E959-4D4C-A655-22EA23616A86.jpg (http://s101.photobucket.com/user/proto19/media/654D0B17-E959-4D4C-A655-22EA23616A86.jpg.html)
http://i101.photobucket.com/albums/m61/proto19/E5080597-1F3A-4612-8583-EB2D04CAE66E.jpg (http://s101.photobucket.com/user/proto19/media/E5080597-1F3A-4612-8583-EB2D04CAE66E.jpg.html)
Two foot drop? Did you fall on it? I've got two NSRs both with bipods. They haven't been dropped per se but they've fallen with no deformation. I know this can happen but if a two foot fall did that, I'm totally surprised.
So it's back to quad rails again? :D
I'd be down KMR alloy quad. Yes please.
So before this thread, where are all the bent slick rails? Just curious.
So before this thread, where are all the bent slick rails? Just curious.
In the KMR thread, lol.
bowman57_2
10-19-16, 13:28
I think ive only ever seen 3 bent rails and they were all on here, ive never seen one in person.
Has anyone tested the strength difference between the kmr and the kmr-a. I'm usually a DD handguard person but I figured bcm makes quality stuff and the kmr-a was 100 dollars less than the DD slim. After reading this thread I'm kind of wishing I would have spent the extra hundred dollars.
How are these rails bending after falling 2 feet?
My space alloy KMR has taken numerous falls, from leaning against a wall to 30' out of trees.
Has anyone tested the strength difference between the kmr and the kmr-a. I'm usually a DD handguard person but I figured bcm makes quality stuff and the kmr-a was 100 dollars less than the DD slim. After reading this thread I'm kind of wishing I would have spent the extra hundred dollars.
I had the same concern so I went with DD 12" Slim Rails for two BCM Mids.
In the interest of full disclosure...
I regret buying those two uppers because the only thing I use a "rail" for is mounting a light (and front sight if the gun doesn't have a FSB). The cost of a BCM BFH 14.5 with pinned A2X and DD Slim Rail was pretty steep. I ended up storing those two brand new uppers and buying two BCM BFH LW 16" and just stuck MOE handguards on them. Light mounting isn't ideal, but I'll probably rectify that with a MI FSB mount.
I ended up storing those two brand new uppers and buying two BCM BFH LW 16" and just stuck MOE handguards on them. Light mounting isn't ideal, but I'll probably rectify that with a MI FSB mount.
Try the MI drop in mlok/keymod handguards with a thorntail on the top rail. I switched from the Midwest FSB mount to that for my FSB rifles. Little better light positioning and lighter weight.
Try the MI drop in mlok/keymod handguards with a thorntail on the top rail. I switched from the Midwest FSB mount to that for my FSB rifles. Little better light positioning and lighter weight.
Thanks for the tip. I saw good reviews for the MI18SS (IIRCr), but had a couple sets of ML MOE HGs so they're on the carbines now. I've been trying to figure out an economical, light and durable (I know...you typically get one, but not the other two, haha) handguard/light mount solution.
I'll look into your suggestion further.
Googled the M/K MI rails. At 6.6 ounces I think they're LIGHTER than MOE handguards! I'm undecided on the Keymod vs MLOK issue. I have the two BCM DD SLIM (Keymod) and have a YHM SLK (Keymod) for sale on a 6920, but recently bought MagPul MLOK handguards for my wife's 6720. Frankly, MLOK LOOKS more durable. After bolting a couple items (KAC light mount for example) to the YHM rail I wasn't sure how I felt about the Keymod system.
Sorry for the thread derail.
EDITED FOR CLARIFICATION.
Try the MI drop in mlok/keymod handguards with a thorntail on the top rail. I switched from the Midwest FSB mount to that for my FSB rifles. Little better light positioning and lighter weight.
Where the hell were you when I ordered both the handguard and the MI FSB mount to try? But I agree completely. I settled on the MI drop-in, and for the weight, profile, and positioning, I have zero complaints. The FSB mount was just too bulky, and made the light kind of a reach.
Good information Nova3930 and Inebriated. I was about to click the "buy" button on several MI FSB mounts. I'm going to try MI DI HG's instead. I just need to decide if I want to go 1913, Keymod or MLOK. Honestly, I have lots of Pic Rail accessories (LaRue scout mounts, LaRue offset scout mounts, etc). I'd prefer to stick with quad rails just because of this reason alone (as stated before - I also didn't like the Keymod attachment, but didn't beat on it so I can't comment on its real durability). I need to spend some time on MI's website looking at weights, because like everyone else I'm in full koolaid mode with regards to dropping ounces off my guns.
Since this is a "slick rail durability" thread....
Does anyone have any experience with MI's SS DI two piece rails? My only experience with "slick rails" that allow selective 1913 sectional attachment is on LWRC ARM handguards. I didn't abuse any of the LWRC I owned so I don't know if those little screws would hold up to hard use. I've read on here that repeated removal weakens the system. For my use, I know exactly where I want to mount my light and possibly a handstop.
ETA: For reference the SS ML weights 7.2 ounces without rail sections attached. 8.3oz with three sections attached.
Good information Nova3930 and Inebriated. I was about to click the "buy" button on several MI FSB mounts. I'm going to try MI DI HG's instead. I just need to decide if I want to go 1913, Keymod or MLOK. Honestly, I have lots of Pic Rail accessories (LaRue scout mounts, LaRue offset scout mounts, etc). I'd prefer to stick with quad rails just because of this reason alone (as stated before - I also didn't like the Keymod attachment, but didn't beat on it so I can't comment on its real durability). I need to spend some time on MI's website looking at weights, because like everyone else I'm in full koolaid mode with regards to dropping ounces off my guns.
I run an M600U off the 12:00 rail in a Surefire RM45 mount, and I use a BFG QR kit for the sling, so I don't actually mount anything to the MI on anything but the 12:00. So, it was a toss-up for me, but I wasn't sure if I wanted to run an Arisaka fingerstop, and since I had a KeyMod version, I got that. Could replace it with any other version, I wouldn't care.
As for KeyMod, and "slick rails" in general (to keep things relevant_;
I've used KeyMod on a KMR and KMR-A, and never had a failure or loosening in thousands of rounds and a lot of actual use. The only M-LOK I've used is on 870 furniture, and limited to one light mount. Proper installation is the important part of KeyMod, and recognizing the limitations of the rail itself is just as important as it relates to both KeyMod as well as lightweight handguards in general.
I know a KMR/KMR-A can dent, twist, or bend if pushed to that limit. A long VFG or light cantilevered a mile off the rail can create a lot of leverage, so before I consider whether or not it'll pull out of a slot, I'm thinking about the integrity of the handguard itself. So I use 12:00 lights, Arisaka fingerstops, and BCM's QD mounts as close to the barrel nut as possible. M-LOK vs. KeyMod just doesn't matter to me, as I've used KeyMod long enough and hard enough to know that it suits my needs, and I know M-LOK must be proven if it's getting contracts.
And to keep things more specific to the topic, I know the KMR/KMR-A fits within my needs for a general-purpose carbine, as well as other widely-used lightweight handguards. An optic is my primary sighting method, the irons are secondary, and I'm not running an IR or visible laser, bipod, anything like that. If I damage the handguard, there is a very low probability that it'll be right when I need it, and even less probability than that is if I damage it enough to alter my backup irons' zero and I also have a dead optic. As a civilian, I'm not going to be hit by an IED or have a Humvee run through my living room when I respond to a bump in the night. If I break a handguard in non-critical use, that sucks, but I'll live... And so far, I haven't broken a handguard in my use. That includes rattling around the back of a Jeep for a whole lot of miles, hitting barricades and door frames in shoot houses, dropping the guns by being a general ape, regularly sliding off vehicle fenders, etc. Though recall above, I don't hang much that can create a lot of leverage off my handguards. The crucial thing to me is that the handguard can't walk forward, and the mounting system can't easily loosen through use.
If the handguard should get damaged right when I need it and the optic fails? I still have my cheek weld, the optic body, and the front sight's general location to make a critical shot within CQB and across-the-yard distances (I.E. where most shots for civilians will be taken, and where I'm most likely to employ the carbine anyway). Everything in life comes with a tradeoff, lightweight handguards are no exception. Be realistic about how you're going to regularly use the rifle, and when you might legitimately need the rifle.
Outstanding reply.
I prefer to mount my lights (M600AA, M600P and M600U) in the 1:30 (LaRue LT752 mount) or 3:00 (LaRue LT272 mount) when using a 12:00 pressure pad (I've moved toward a forward c-clamp hold). This allows me to slip my hand back slighting and thumb the pressure pad. I often use a handstop to help me index (this even includes old KAC broomsticks - I don't hold them like VFG's ... use them like any other handstop). I always sling as close the the barrel nut as possible at 9:00 (right handed shooter).
I had a DD MFR12 on a 6920, and could torque the tube over to toward 9:00 ever so slightly. I removed and reinstalled the handguard. It tightened up the second time, but still could move (gap between the HG and Receiver face). Otherwise, like yourself, I don't anticipate a scenario where I would render my rifle inoperable through normal use. (NOTE: I've gone full circle and am back to FSB instead of front flips on some sort of rail so the chance of loosing both sighting systems ... RDS and OS ... are very low).
4204842049
Sorry for the tiny pictures. I don't know how to post images "normal size".
Where the hell were you when I ordered both the handguard and the MI FSB mount to try? But I agree completely. I settled on the MI drop-in, and for the weight, profile, and positioning, I have zero complaints. The FSB mount was just too bulky, and made the light kind of a reach.
lol I just settled on that configuration recently myself soooooooo
going back to the durability question though, it's the age old engineering triangle. light, strong, cheap....pick any two.
There's lots you can do with smart engineering but there's always a point you've got to compromise somewhere.
looking at the kmr design, imo their engineer earned his paycheck. imo it's a very efficient design and I'm impressed they can sell it for the $ they do and make a profit. that said a kmr that's a little heavier would give you a step up in strength. for normal use age I'm not sure that's necessary though.
Sent from my SAMSUNG-SM-G930A using Tapatalk
Powered by vBulletin® Version 4.2.5 Copyright © 2024 vBulletin Solutions, Inc. All rights reserved.