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Geissele SMR MK4 vs MK5 Handguard Side by Side Comparison

Posted on May 19th, 2014 by ar15news

I wanted to show you guys a quick visual comparison between two of my favorite Geissele rails, the SMR MK4 and SMR MK5. Both are fairly new (released in the last year) and I know it can be hard to figure out what’s what just by looking at the “MKX” naming system. The Geissele SMR MK4 and MK5 are some of the most solidly built KeyMod rails out there. As you’ll see below, you can’t go wrong with either one as they both are awesome options. Click on the images for a larger view.


First lets look at the MK4. The Geissele SMR MK4 is kind of a hybrid rail. It has KeyMod mounting slots at 3, 6 and 9 o’clock positions with small 1913 picatinny rail sections up front at 3, 6 and 9 o’clock and a full length picatinny rail at 12 o’clock as well. There are a few other rails like this on the market and as weird as it may seem it makes a lot of sense. The number one best selling KeyMod accessory is…the 1913 rail sections which people always mount toward the front of a KeyMod rail.

620 Geissele SMR MK4 4

One of the main reasons people are hesitant to switch from their quad rails over to a new system such as KeyMod is because they have so many “Quad Rail” accessories, especially light mounts. The MK4 allows you to have an integrated quad rail section to mount your lights to while offering KeyMod slots to use for the popular Rail Covers from companies like Noveske, etc. I’ve personally found that the Geissele rails are so well finished that I don’t even need any rail covers. 

620 Geissele SMR MK4 4

I really dig the look of the MK4. Just something about the use of both 1913 and KeyMod just looks cool. As you can see in the pictures below, it makes for one awesome looking rifle and offers a super solid rail with lots of options. The MK4 would be perfect for those who are either on the fence about 1913 vs KeyMod or those who have specific 1913 light mounts, bipods, etc. that you want to still use and don’t want to buy extra mounts to make them compatible.

620 Geissele SMR MK4 4


Now lets take a look at the MK5. The Geissele SMR MK5 is built how KeyMod was designed to be used with KeyMod mounting slots all the way out to the tip of the rail. This gives you the most flexibility with mounting KeyMod accessories such as Light Mounts, Handstops, QD Sling Mounts, rail sections, etc. 

620 Geissele SMR MK5 1

As you’ll notice, the KeyMod slots are at the 3, 6 and 9 o’clock positions with a full length picatinny rail section at 12 o’clock like the MK4 does. Both rails look very similar, however with the MK5 there are no short rail sections at the the front of the rail and there are no front QD Sling Mounts. This design is all about letting the “KeyMod Convert” have as much flexibility as possible in mounting their new KeyMod accessories. 

620 Geissele SMR MK5 1

620 Geissele SMR MK5 1

As I mentioned before, there really is not wrong decision to be made here. I love both of these rails. Its more of a personal preference thing when it comes to deciding between these two rails. Both feature the amazingly high degree of quality you would expect to find with a Geissele rail and look freaking sweet.

I had planned on waiting for Geissele to get the newer MK5’s in-stock but they are such a hot item I decided to just give you a link to a Geissele dealer and AR15NEWS friend, Weapon Oufitters, since they have both the MK4 and MK5 in-stock right now. That way if you like what you see you can pick one up for yourself. I’ve also put some information below for great KeyMod accessories too. 

You can purchase the Geissele SMR MK4 and MK5 rails at

As always, you can peruse the website as well but with the high demand of these rails they are not all in-stock. 


On a side note, for those looking for KeyMod light mounts, handstops, sling mounts, etc. you can check out my personal go to which is Plus you can save 5% by using our discount code “ar15news” at checkout. 

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