View Full Version : Looking for advice on Rail Purchase.
All,
First post in the Forum, and was looking for advice. (Please feed the noob)
I've got a Colt 6920 that I'm looking to upgrade. In fact, I just purchased a Magpul ACS to replace the factory collapsible stock.
First and foremeost, I am not an "operator". I never will be. That being said, I do want this rifle to be reliable enough to defend myself and my family with it. I do not want any junk, and I'd rather save longer and get items that are dependable all the time.
Here is what I'm looking for in a rail and hopefully you all will give me the info I need to properly set it up.
The equipment I would like to run on my Carbine is a follows:
Aimpoint Comp ML3 in a LaRue Cantilever Mount
Some of BUIS
Aimpoint 3x magnifier (possibly down the Road)
Magpul AFG or a VFG
Possibly a side mount Flashlight.
The attributes I want in the rail are as Follows:
Light as possible while having a rock-solid lock-up.
Small height and width (am only 5'9" and have smaller hands)
Continuous Top rail is preferrable
Rail on the Colt and the Handguard need to match up exactly.
I have two questions that I don't know the answer to:
1. Are all of the DD and LaRue rails Free Float? If not, what is the real advantage in free floating them versus not?
2. On a 6920, what length rails can I use and still keep the front sight base? If I want to remove the FSB, what kind of gas block will I need, and what rail options will that open up?
So, based upon all of this, what would you all reccommend?
rifleman2000
01-26-10, 14:15
You will not need free float unless you are doing precision shooting, such as sniping or bench matches.
I would recommend a KAC from Knights, it is the only rail I have experience with but it definitely does the job.
Belmont31R
01-26-10, 14:23
All current DD and LaRue rails are free float although I believe DD is coming out with a drop in unit that is not.
Freefloat leaves the barrel "floating" with no secondary contact past the barrel nut. Its desirable for accuracy as it allows the barrel to flex consistently under recoil, and does not alter the harmonics. On a gun like a 6920 accuracy is not the primary concern so don't get too caught up on free float vs. non free float.
The DD Omega has the continious top rail and is free float although the profile has a bottom rail that extends down further than most other rails.
The KAC RAS is not free float but has a slimmer profile. It attaches via the cap just behind the FSB, the delta ring, and the barrel nut. Very similar to the stock plastic handguards. In addition to that it has a hook under the top rail that goes between the barrel and barrel nut. You tighten the hook, and it "clamps" the rail in place. The bottom rail, unless you get the SAS version, is simply held in place by the handguard cap, and the tension from the delta ring.
There are other drop in rails. I believe MI makes some for instance. I dont have any experience with them but based on lots of user feedback they are OK at best. The DD and KAC are more consistent in performance and quality.
For a carbine gas system such as the 6920, and using the standard FSB a 7" rail will go to the back of the FSB. There are other rails that go around the FSB so it sticks up through a hole in the rail. DD makes some as does KAC. These will be free floating. They add much more rail space while still retaining the stock FSB. You can also install a lo-pro gas block or shave down the stock FSB into a low pro style setup, and use a longer rail. I like the cut down FSB because you retain the stock FSB pins which is an added measure of security in keeping the gas block in place. Many aftermarket low pro gas blocks are held in place with set screws, and are not generally regarded as being as secure of a setup as pins. You can pin a lo pro gas block, too. Most do not.
DD or LaRue are both GTG.
I put the DD Omega on my gun and like it a lot. It goes on with out removing the FSB.
2. On a 6920, what length rails can I use and still keep the front sight base?
I'm not an expert here, but...
A 7" (carbine length) DD Omega rail is free float and will attach without removing the FSB. I just put a 9" Omega on a mid length upper and it was painless. It took me about 30 min.
DD and others make a longer rail for a carbine length gas systemthat leaves an opening for the FSB, but requires removal of the FH and FSB for installation. You then need a receiver block, vise and barrel wrench. Can't really help you with a low gas block since I've not mounted one. I have Dremeled off the upper part of a couple of standard FSB so I could mount a round FF tube. That might be an option with a rail, but I'm not sure. If you go that route and later change your mind, it's a gunsmith proposition to drill and pin a new FSB.
ForTehNguyen
01-26-10, 14:37
I doubt you will notice any anything major in accuracy on free float vs non free float for carbine use.
A Daniel Defense Omega 7.0 will make the top rail contiguous
I have a 12" FSPM from DD. I like the rail quite a bit. Like others have said, DD, Larue, and Knights all make quality products. I would not hesitate to use either on my duty rifle. The seven inch rails will let you keep the front sight base without using a low profile gas block. Another option would be the rails that allow you to keep the front sight gas block while haveing more rails past the front sight.
https://www.danieldefense.com/?page=shop/detail&product_id=29
citizensoldier16
01-26-10, 14:53
I'm not an expert here, but...
A 7" (carbine length) DD Omega rail is free float and will attach without removing the FSB.
Yes, it does. My DD 7.0 FF rail with the FSB still attached.
http://i293.photobucket.com/albums/mm53/emtjmd216/100_0674.jpg
The DD Omega has the continious top rail and is free float although the profile has a bottom rail that extends down further than most other rails.
Yes, it does. My DD 7.0 FF rail with the FSB still attached.
http://i293.photobucket.com/albums/mm53/emtjmd216/100_0674.jpg
Does anyone know how much taller the Daniel Defense Omega Rails are than a more standard rail (such as the Larue 7")? My concern is trying to use the Magpul AFG on the DD Omega while having smaller hands like I do.
What are the functional differences between the DD AR15 Lite Rail 7.0
https://www.danieldefense.com/?page=shop/detail&product_id=60
and the DD Omega Rail 7.0?
https://www.danieldefense.com/?page=shop/detail&product_id=109
Does anyone know how much taller the Daniel Defense Omega Rails are than a more standard rail (such as the Larue 7")? My concern is trying to use the Magpul AFG on the DD Omega while having smaller hands like I do.
DD Omegas are the exact same height as DD M4 and Lite rails. The Larue bottom rail is 0.2" shorter than the DDs.
ForTehNguyen
01-26-10, 16:01
What are the functional differences between the DD AR15 Lite Rail 7.0
https://www.danieldefense.com/?page=shop/detail&product_id=60
and the DD Omega Rail 7.0?
https://www.danieldefense.com/?page=shop/detail&product_id=109
Omega by far has the easiest installation, that's the primary difference with the Lite series. DD's have a quick disconnect socket for slings, Lite's dont
decodeddiesel
01-26-10, 16:59
If I were buying a rail for a 6920 today I would get the Daniel Defense RIS II FSP (https://www.danieldefense.com/?page=shop/detail&product_id=134). However, there's a few things to consider before you add a rail to your carbine.
First of all before you drop $250+ on a fancy rail system for that weapon, what sort of training and professional instruction have you had in operating that weapon? If the answer to that question is none then frankly the money you would have spent on the rail is much more wisely spent on a class from a reputable trainer.
Secondly do you have plenty of magazines and ammunition? If not DSG Arms (http://dsgarms.com/index.cfm/product/2605_25/magpul-window-pmag-gen-1-non-rev-m-foliage-green---10-pack.cfm) has 10 packs of Pmags for $100. I would strongly suggest this. Ammo is still pretty expensive, but there are deals to be had. I wouldn't buy a single accessory until you had at least a couple thousand rounds stockpiled.
Finally have you considered a Magpul MOE handguard? This is an inexpensive way to mount all of those accessories you have mentioned without breaking the bank.
DaBears_85
01-26-10, 23:14
You will not need free float unless you are doing precision shooting, such as sniping or bench matches.
I would recommend a KAC from Knights, it is the only rail I have experience with but it definitely does the job.
I have to second that notion. I have a 6920 with a Knights Armament M4 RAS on it and LOVE it. It's a perfect fit and is rock solid. I'm an 11B (infantryman) in the Army and it's what we use standard on all our carbines.
lethal dose
01-26-10, 23:24
dude... if you're looking for small diameter with continuous top rail... look up the troy trx extreme battlerail. it also comes with 3 small pieces of rail to bolt on- for a light and vfg. super light and low profile.
The attributes I want in the rail are as Follows:
Light as possible while having a rock-solid lock-up.
Small height and width (am only 5'9" and have smaller hands)
Continuous Top rail is preferrable
Rail on the Colt and the Handguard need to match up exactly.
Your above requirements all seem to fit the DD Omega Perfectly.
Light as possible while having a rock-solid lock-up. -- Omega
Small height and width (am only 5'9" and have smaller hands) -- Omega
May be .02" higher than Larue rails but it is very slim in width.
Continuous Top rail is preferrable -- Again, an Omega feature.
Rail on the Colt and the Handguard need to match up exactly. -- Shouldnt be a problem on your Colt. In reality, I have yet to see one that doesnt line up perfectly.
Oh ya, and its freefloat and it drops right in. :D
Personally, if the lack of rail space is not a current issue, I would recommend not touching your FSB at all.
I am kind of a noob myself. I just purchased a Midwest Industries 2 piece free float hand-guard, and I could not be happier! I don't think the quality can be beat for the price, these are not cheap junk. It is very solid, so solid that now I have to get an accuwedge because now I can really feel the play between the upper and lower receiver. I have seen no tool marks or any defects of any kind. They are supposed to have a constant rail when installed on an flat top receiver, I have an A2 carry handle so I can't be sure, but it fits really tight to the receiver so I imagine it does. It installed in like 25 minutes. (just because I was careful could have done it faster) They aren't noticeably any heavier than the plastic hand-guards. I don't know how they would fit your hands, but I think they are comfortable for me at least and I also have small hands. I have a 20" barrel and I only paid $228 for them so I am sure yours would be cheaper.
Sounds like the Omega will fill all your needs. If you don't have a RDS yet, I would suggest spending your money on one vs the rail. I sold my Omega and bought an Aimpoint because accurate and faster shots were more important than hanging a VFG and light on a rail. I attached a light to a MI FSB mount and don't use a VFG.
1811tactikool
03-07-10, 17:25
dude... if you're looking for small diameter with continuous top rail... look up the troy trx extreme battlerail. it also comes with 3 small pieces of rail to bolt on- for a light and vfg. super light and low profile.
This...
Or a DD Omega or Omega X. Extremely lightweight, very well built.
Sounds like the Omega will fill all your needs. If you don't have a RDS yet, I would suggest spending your money on one vs the rail. I sold my Omega and bought an Aimpoint because accurate and faster shots were more important than hanging a VFG and light on a rail. I attached a light to a MI FSB mount and don't use a VFG.
I have the Omega on 2 of my rifles and love it. The KAC is good too but I prefer the DD.
All Daniel Defense is good to go, but if you desire something smaller in diameter, and don't mind a little more complexity in mounting than a drop in, you may want to look at the Troy TRX or VTAC.
Sounds like the Omega will fill all your needs. If you don't have a RDS yet, I would suggest spending your money on one vs the rail. I sold my Omega and bought an Aimpoint because accurate and faster shots were more important than hanging a VFG and light on a rail. I attached a light to a MI FSB mount and don't use a VFG.
This was very good advice.
I added an Aimpoint T-1 to my AR and still have the factory handguards.
Honestly, at this point, I have no reason to replace them. I don't see the need for the extra rail space at this time.
What are the functional differences between the DD AR15 Lite Rail 7.0
https://www.danieldefense.com/?page=shop/detail&product_id=60
and the DD Omega Rail 7.0?
https://www.danieldefense.com/?page=shop/detail&product_id=109
Anybody else notice the lite is 8.5 ounces compared to 8.0 ounces for the Omega 7? The 9.0 Omega is also lighter than the 9.0 LITE and the OmegaX 9.0....
I have an Omega 9 on a Middy it went on quickly, is sturdy and I didnt have to deal with a wrench or proprietary barrel nut.
ParkisMaximus
05-28-10, 18:36
check out midwest industries inc .com they have a t series free float rail system that is ****in awesome. that combined with rail latters has a very nice look.
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