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Replacing Daniel Defense Quad rail. Need info.

12K views 32 replies 10 participants last post by  faawrenchbndr 
#1 ·
I have a factory Daniel Defense MK 18. I would like to get rid of the factory quad rail and get a replacement MLok (or POSSIBLY a Keymod) lighter rail that is stil 9.5 inches just like the factory DD rail. Money isn't really my problem. I read what I thought is that a Geissele MK8 9.5 inch rail will easily install and replace the factory rail. I am looking for any good brand rail that I can get that I can easily take the factory quad rail off and install an MLok without a lot of work. What rail can I get? Will the Geissele work without a ton of work? Thanks guys!
 
#2 ·
I'm not sure if you need a special wrench for the DD rail barrel nut but you'll need some basic tools to replace a rail. You'll need something to hold the upper in a vise to loosen and tighten the barrel nut. Most rails clamp on or screw on to the barrel nut. I would recommend one that clamps on rather than screw on. It's not hard to do with the right tools. You'll want to use some grease on the barrel nut threads. Wheel bearing grease will work but Aeroshell 33ms is the recommended grease.

Since you said price isn't really a factor, I would recommend a SLR Rifleworks rail. It's in the same price range as a Geissele rail. I have a Solo 13" on a 14.5" barrel and love it. They have a few models with various rail options (keymod or mlok, reg, lite and ultra lite) and it clamps onto the provided barrel nut.

http://slrrifleworks.com/index.php?route=product/category&path=66_106

Both SLR and Geissele have a sale this weekend.

 
#13 ·
#5 ·
I like my noveske Nsr rails. But both rails require proper barrel but wrenches to remove or install.

Personally I would sell your upper and buy another upper with the rail you prefer, but if you have the brown mk18 ris rail, it's highly sought after and can go for upwards of 300 bucks.
 
#8 ·
I should have stated that I have to go with around a 9.5 so that I can fit my suppressor on it. I have really thought of just selling the upper as well. I don't really know why, I have a 6.8 Bison Armory 11.5 inch SBR in MLok that I really like. Though the MK18 quad rail is a bit heavier in the SBR platform it is very easy to get a grip on and control the gun. I really want to try this MK18 with a super thin and super lightweight MLok and if I don't like it put the quad rail back on. That's the main reason I wanted to find one that is easy to install. Knowing what I just added which should I look into guys? Also, I don't sell that many of my guns, but my MK18 upper is in absolutely excellent condition and if I wanted to sell it where would be the best places to sell an upper like that? Thanks guys
 
#9 ·
All the rails mentioned above are great choices. It comes down to what YOU like.

If you decide to sell it, I would post it on AR15.com and maybe m4carbine.net. You'll have an audience that knows what they're looking at and how much it's worth. If it's priced too high, it won't get any interest. Priced just right or a bit low and it will sell in less than an hour.
 
#10 ·
All the rails mentioned above are great choices. It comes down to what YOU like.

If you decide to sell it, I would post it on AR15.com and maybe m4carbine.net. You'll have an audience that knows what they're looking at and how much it's worth. If it's priced too high, it won't get any interest. Priced just right or a bit low and it will sell in less than an hour.
What's a fair price on a used, though in excellent condition MK18? Though that MK8 Geissele rail looks pretty sweet if it isn't hard to put on my MK18!
 
#12 ·
I have no idea how much it's worth used. Some guys here have already mentioned $300-$450. Maybe google recent used sales and go from there.

As Jack Black said, ease of installation is relative. I recently upgraded my first AR build from a Magpul MOE handguard (clamshell) with a free float rail (Matrix Arms) and it took me less than 15 mins. I had to replace the barrel nut and gas block. I do have Snap On tools and work on my own trucks, cars and motorcycles so working on an AR is really easy for me. I also have all the necessary AR tools.

The MK8 has a similar install to my SLR and Matrix rails so very easy to install, IMO.
 
#18 ·
You're obviously not an operator and don't need the pin :p

I'm not a fan of the NSR because of the way it mounts with screws. That's probably why they use the pin. I've never handled one so I can't say for sure but I think the clamp on types like the Geissele and SLR is more secure and easier to install.
 
#20 ·
Looks like the pin is to prevent the barrel nut and rail from spining. I wouldn't worry about that. The issue I have with the type of mount where you use screws to secure the rail to the barrel nut is that the holes for the screws have some play or slop so you need to make sure the rail is positioned correctly before tightening them all down. There is also some slop, although minimal with the NSR, between the rail and the barrel nut. On the clamp on styles, they are more secure all around the barrel nut. This is more just splitting hairs and both types should work. I'm more confident with Noveske's implementation of their design than I would be with a chinese knock off. The clamp style is almost idiot proof to install. I have the first gen SLR rail (3 yrs old?) and they made some changes to the clamp. I'm not sure why but I had one guy pm me to see if I wanted to sell my handguard as he liked the first gen clamp better than the current version. The Matrix Arms I upgraded my 1st AR is a similar clamp style and very inexpensive ($80 with a low profile gas block shipped!)



I've seen specs for barrel nuts from 30ft/lbs to 90ft/lbs. Even at 30ft/lbs, it would be VERY hard to loosen a barrel nut with the rail. Both my AR barrel nuts are set to about 50ft/lbs and have not moved at all. When I replaced the rail on my 1st AR, the nut was still nice and tight.

I can't stress enough that you should use grease on the threads. Aeroshell 33MS is highly recommended but you can use most moly based high temp wheel bearing grease. Do NOT use anti-seize.
 
#27 ·
Alignin
Looks like the pin is to prevent the barrel nut and rail from spining. I wouldn't worry about that. The issue I have with the type of mount where you use screws to secure the rail to the barrel nut is that the holes for the screws have some play or slop so you need to make sure the rail is positioned correctly before tightening them all down. There is also some slop, although minimal with the NSR, between the rail and the barrel nut. On the clamp on styles, they are more secure all around the barrel nut. This is more just splitting hairs and both types should work. I'm more confident with Noveske's implementation of their design than I would be with a chinese knock off. The clamp style is almost idiot proof to install. I have the first gen SLR rail (3 yrs old?) and they made some changes to the clamp. I'm not sure why but I had one guy pm me to see if I wanted to sell my handguard as he liked the first gen clamp better than the current version. The Matrix Arms I upgraded my 1st AR is a similar clamp style and very inexpensive ($80 with a low profile gas block shipped!)



I've seen specs for barrel nuts from 30ft/lbs to 90ft/lbs. Even at 30ft/lbs, it would be VERY hard to loosen a barrel nut with the rail. Both my AR barrel nuts are set to about 50ft/lbs and have not moved at all. When I replaced the rail on my 1st AR, the nut was still nice and tight.

I can't stress enough that you should use grease on the threads. Aeroshell 33MS is highly recommended but you can use most moly based high temp wheel bearing grease. Do NOT use anti-seize.
Aligning an NSR rail is a piece of cake. Take any picatinney mount you have sitting around and clamp it to the rail/receiver so the front end of the mount is on the rail and the rear is on the receiver. Done. Tighten screws and everything will be lined up perfectly.
 
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