Wanting to complete a precision build and debating either m-lock on all but top or the combat rails with all sides using picatinny rails. Weight or handling is not a concern. My decision is based on which attachment rail gives me the most options. I have read the picatinny rails are still the best as far as what is compatible to attach to them directly. I would certainly need to attach a bipod and possibly a verticle handle of some sort. Advice? Btw I'm looking at either the Aero Enhanced or the MI Combat.

Midwest industries combat rail gives you 7 sides of mlok attachment and a rail on top.    Cant get much more attachment options then that.

Wasn’t clear. Will try again. MI sells a ff handguard with 4 sides of pic rail.  They also sell hg’s with a combo of both picatinny and m-lok. My question really is if I had to pick one or the other which one?  I thought I heard pic was still the standard most attachments use it instead of m-lok?

Do their rails have any anti rotation tabs or feature. I watched one video of a guy installing one, and he had to apply this green glue stuff that came with rail all around the barrel nut. Being a person who swaps rails a lot, this is less than desirable.

MI rails are GTG, and are my favorites.

If I were to get another Aero rail, it would be the Atlas R (full pic rail on top) instead of the Atlas S...but I like my MI Combat rails better anyway (they are lighter and have a bit more depth for the built in QD spot).  

OP, pic is the standard, but you just add a piece of pic rail via mlok slot where ever you want pic rail.   With that said, a lot of companies make direct mlok attachments.


Aero Atlas S


Aero Atlas R


MI Combat rail - You can see it even comes with a 5 slot mlok/pic rail attachment to put where everyou want.


ETA - both have anti-rotation tabs.  MI has them up top, Aero has them along the sides.

Panthermark,

Thanks for the thorough response with the pics. Answered my questions.

I did name the wrong handguard. I meant the MI Quad Rail HG. I understand now that Pic is still the standard and that even so many companies have direct m-lok attachments. So last question. If I bought the Quad Rail, other than limiting direct m-lok options, would I be buying an outdated HG?

A few issues with traditional quad rails compared to M-LOK rails, depending on your preferences:

- Quad rails tend to be bulkier, with a few exceptions.  Depending on how big your hands are and how you like to handle it, this might not matter.
- Quad rails tend to be heavier in general.  With lighter weight comes less heat dissipation, and the MLOK HGs can get hot during mag dumps/rapid fire strings and such.
- Cheese grater effect is real on uncovered quad rails.  I use rail ladders to keep the weight and bulk down, and they make the rails more comfortable.  Full covers give better heat protection but add even more bulk to already bulky handguards.

For MLOK, they tend to be slimmer and lighter out of the box, but adding attachment points can interrupt the slimness, making a lumpier profile.  This can be re-configured, of course; stuff can be shifted around, different gear profiles used, etc.

Less bulk and lighter weight are a couple of the driving factors for MLOK popularity.  I have both, and prefer both lighter and slimmer, so the quad rails are mostly on things like my A4 clone build, which is heavy and bulky by definition.

To be honest...yes, the quad are a bit out-dated.   You can turn an mlok rail into a quad rail with pic rail attachments (via mlok), but you can't get rid of unused pic rail son a quad rail.  However, it also depends on your build and what you might be running on the side rail (laser).  In that case, a solid quad rail might make more sense over a picee of pic rail that is added via mlok.   I think the biggest issue with quad rails is that you end up covering all the metal slots with rail covers so you don't grate your hands.


Edit "don't" grate

Ok. Thanks again. That all makes sense.

No prob.  
Two more things if you go Mlok.
1. Keep in mind the internal diameter of the rail, and what gas block (and muzzle device if rail is longer than barrel) you use.    A lot of mlok rails are "slim" profile, and when you attach something via mlok, the attachment connectors are on the inside of the rail.  You want to avoid having the connectors touch your gas block and throw off your accuracy. Just something to remember with bipods or forward grips.  You may have to move them forward or backwards an inch to avoid contact with the gas block if the rail is really slim.

2. If you add a piece of mlok rail or grip of something, and it is "behind" your gas block (between gas block and receiver).....you "might" have to remove that attachment before you can remove your rail.   Not a big deal since it takes about 20 seconds to do....but just annoying when you forget about it.   Depending on the rail and how long of an mlok screw is used, the screw might bump up against the gas block when you go to remove the rail (thus you have to loosen the mlok screws a bit to get clearance).  

Picatinny rails will typically give you more rigidity.  If you want weight savings, go M-Lok.  There's so many accessories and options that it's super easy to adapt anything to M-Lok with rail sections if necessary.  Essentially, if you aren't beating the crap out of it, I'd probably go with an M-Lok rail.

That being said, I don't have a lot of experience with various handguards, but I love Midwest Combat Rails.  They look good, feel good, and are super easy to install.  No green adhesive necessary with the newer ones.  Have a 14" and 15" on a couple rifles and wouldn't hesitate to buy another.

Definitely something to be aware of.  Also, Magpul has shorter screws for the thinner rails to help avoid this with attachments. Gas blocks I would just go with the low profile ones, unless you need an adjustable, which most of the time you don't unless you're using a suppressor.

It really depends on what you're hanging off of it and how tough an environment you're planning on using your gun. The Picatinny handguards are extremely robust, but heavy and, to most, not ergonomic at all.  Regardless of type of accessory attachment method, most people only use the front of the handguards at 12 o'clock and 2 o'clock or 10 o'clock for a BUIS and a light, and are mostly installing free floating handguards for looks and the perceived added accuracy, even if the guns are rarely used. If you like the looks of the Picatinny handguards, by all means buy them, but they have been superseded by Mlok handguards, which are the current go to pattern. My suggestion would be to buy an Mlok handguard from a reputable manufacturer. I'm sure there are decent quality, cheaper brands out there, but the top players seem to include Geissele, Centurion, BCM, Midwest Industries, and Aero Precision.  of those mentioned, my guess is Aero Precision and Midwest Industries sell the most volume. They're all very similar aesthetically, in materials, and even on how they attach to the barrel nut, but the better designs lock up tighter or stronger, don't rotate on use, and of course look cooler because they're used by various special forces and elite units.

I went with Aero for this gun as well as the pistol build I am doing. I actually wanted the MI for the pistol and they were in stock, until I got ready to order the next day.  Maybe next build? Lol.  Thats a good point on the bipod mounting issues. 18" barrel and 15 " ff handguard so hopefully I'm fine.

When buying a free float modular rail (typically M-Lok these days) it is worth it to look for one with slots for 45 degree offset, and not just 90, 180 and 270.

The DD 12" free float on my Recce build is that way and that is a big help.  I have nothing on that rail except a folding front sight up top, a mini picatinny at the front bottom for a QD Harris bipod, and the 45 degree for an offset mini-reflex Deltapoint Pro.  It is otherwise bare.  Very easy to shoot and rails only where needed.

But, don't sell free float quads short, especially for light M4 carbine gas port builds with A2 FSB.  Daniel Defense' Omega 7.0 is a true free float, drop in that replaces the mil-spec handguards, weighs only 7.6 ounces, the same as the plastic hand guards (read that again), and is slimmer, even with its pic slots, in cross-section.   Delta ring and front guard cap are retained.  Only 1.9" wide.  With ordinary ladder covers, its very easy to grip.  I run one of those on my "must not fail" HD carbine to support a vertical grip and weapon light.  Sometimes a short quad makes more sense than a long modular rail, and the longer the rail, the more weight you add.

For those with M-Lok accessories, DD also makes M-Lok versions of the Omega.