You don't have to kit it out completely. Keep the one you like least iron sights only. I would buy pieces as they come back in stock and after a couple of years you'll have everything you need!

Your not missing much. Slimmer profile, negligible weight savings depending on barrel profile, and mid length gas system are the only draws.
Honestly, the 14.5 Urgi hasn't been getting as much air time as my Ris'ed uppers.

However... one combination I've been favoring recently is a 9.3 Mk16 paired with a Fn Socom profiled 10.3.
You'll shave 4ozs when compared to a standard Cqbr upper with the benefits of a heavy barrel, but that's for another thread.

Lots of chatter on the 11.5 MK16. I have one as a spare upper/90% completed project and while I haven't shot it, I sold a 9.3 railed/10.3 barreled MK16 upper after building and handling the 11.5. A full Colt/DD/SF4P blah blah. One simple reason - another mlok slot vs the 10.3. 5 versus 4. That 5th mlok slot makes a lot of difference when it comes to mounting accessories. Now I wish I hadn't sold anything AR related over the last 2 years due to the current state of affairs but it is what it is.

I bought a black Geissele 13.5" MK16 rail, a black URG-I Airborne charging handle (no logo), a Colt M4 barrel with the Colt cut down, low profile gas block and a 4 prong Surefire SOCOM flash hider.

I have a Geissele upper receiver and Geissele M4A1 BCG.

I was thinking to paint the rail before assembly or paint everything together after assembly.

I took my close to $10k ultra-OCD CQBR build and did this...

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I was thinking of going the other way and swapping the 9.3" MK16 on my URG-I for a RIS II.

I have enough parts for both now though.

This might have been covered but has anyone else seen a shift in zero with a thermal or pvs30 clipped onto the rail with the 14.5

Mine had a 4 inch shift. My Ris ii had none

I don't see how it would make a difference. If anything, the MK16 should have better alignment than the RIS II since it utilizes a tight fitting, long barrel nut.

Well if the 11.5s ever come online I'll probably do the same.

Barrel harmonics?

Going from an M4A1 heavy barrel to a 14.5" URG-I barrel would probably be noticeable for POI shift with a suppressor. I can't think of how that would have much to do with what you are experiencing though.

Is your gas block touching the rail while firing on the URG-I? Do you have the low profile DD gas block?

Just want to give a shout out to Justin and everyone else from Geissele on their excellent customer service and work. I had purchased one of the Colt clone correct URG-I uppers during the first initial run back in 2018 I believe when they were offering the golden tickets for the surefire rc and surefire light. Long story short anyone who purchased these, knows the issue with the DD mk12 gas block clearances, in which some were making contact with the rail. A few members here have documented their issues and repairs with Geissele shaving the profile of the gas block, touching up the gas block with paint or cerakote then reinstalling it to remedy the situation. From what I understand that was the initial remedy, towards the end of these repairs from my understanding Geissele was able to source some of the DD low profile gas blocks for repairs with these specific clone correct uppers. Geissele went the extra mile on my upper and was able to source a leftover low profile DD gas blocks they had on hand and swap out my DD Mk12 gas block to keep my upper correct!

I used the 35% off coupon that came with my 10.3" URG-I upper and bought a DDC 10.5" MK16 and for an 11.5" barrel  and I bought Spikes Tactical FN CHF lightweight 11.5" barrel.

The gas port in the barrel is a little large and I might hold out for a Daniel defense 11.5" barrel before assembly.

The lightweight 11.5" barrel is the same weight as a government profile 10.3" barrel, 18oz.

I bought the URG-I DDC Airborne charging handle.

It differs from the regular one in not having the white Geissele, "G" logo and doesn't come in commercial packaging, just clear plastic.

I believe DD has stated they have since changed the profile of the, "commercial" MK12 gas block to fit more rails.

I bought one when they came out, but I haven't tried it for fit in the MK16 rail.

I got an in stock notification from DD that barrels were back in stock. Email was under a minute old when I opened the link to find nothing in stock. I know times are hard and parts harder to come by but i was surprised at this still.

I too got the same email and disappointment. I wish I could at least backorder one from somewhere.

I'm never one to complain about things like this but i sent a polite email to their CS saying maybe double up next time. Just for the chance that it'd open it up to maybe a whole minute and a half for consumers instead of the 45 seconds or so this felt like

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Since people are posting some 10.3s, I’ll throw mine in.

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I'm thinking of adding some color to mine.

Which paints are close to any of the shades of DDC?

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Thanks, I hadn't thought of Krylon.

My 9.3" and 10.5" rails are both DDC, but my 13.5" rail is black.

I was thinking to maybe try some of the Aluma-hyde II colors.

I see they have, Earth Brown, Coyote, Desert Tan and Magpul FDE.

At first I thought I might paint the whole rifle, but I think I'll paint the rail, off of the rifle.

Anyone ever order an upper from optics planet?

My velocities over a chronograph are a full 100+ fps slower than those listed in this chart. M193 usually running around 3150 from a 20" barrels, M855 around 3050 fps.

Ambient temperature makes a difference, but I'm always slower than these numbers even on hot days.

That's closer to 50 slower unless my math is wrong. This was from a bolt action with a non chrome lined barrel with a .223 chamber IIRC. Also, could be a higher altitude.  Kind of irrelevant what the numbers are though, just comparing the difference between lengths.

Do you think an 11.5" is noticeably more effective than a 10.3"? Do you think a 14.5" isn't noticeably more effective than an 11.5"?

The chamber design does affect the velocity.

The original M16 used the standard 223 Remington chamber and the stated velocity was 3240 fps at 24 meters from a 20" barrel, for a nominal muzzle velocity of 3300 fps.

In effort to improve reliability, Colt later designed their own 5.56 chamber design, notably with a longer throat and used in the M16A1.

The stated velocity of the M16A1 was 3165 fps at 24 meters with no reference to velocity at the muzzle.

Early M855 ammo used the same powder as M193 ammo.

The M16A2 manual calls for a muzzle velocity of 3100 fps with M855 ammo and approximately 3250 fps with M193.

Note that the chamber pressure limit of M855 ammo was 3,800 PSI higher than the original pressure limit of M193 ammo.

M855 was supposed to have velocity, trajectory and gas port pressure fall within NATO specs.

The NATO 5.56 ammo test barrel is 18" long with a 5.56 chamber designed by FN.

The US military preferred to stay with a 20" test barrel for testing 5.56 ammo.

When the M4 first came out, the original M855 ammo produced a muzzle velocity around 2900 fps.

After the Army adopted the M4, it was found that the gas temperature going through the gas system was higher than desired.

A new powder, with a lower burning temperature was used in later M855 ammo.

This new powder was loaded to spec'd velocity from a 20" test barrel.

Later it was found that the M4 muzzle velocity was significantly lower with the new powder than the previous M855 ammo.

Rather than spend money improving M855 any further for the M4, the US Army developed a new, non-NATO bullet, with a new powder, specifically for performance in an M4 in the M855A1 ammo.

Several NATO member countries do load both NATO spec ammo and 55 grain FMJ ammo and some load their 55 grain FMJ bullets to same pressure limit as NATO ammo, which can get around 3300 fps from a 20" A2 barrel.

That foreign ammo is not M855 or M193 ammo, even if it might be old as such.

In an A2, I get around 3200 - 3250 fps with USGI M193 ammo and close to 3100 with USGI M855 ammo.

Some commercial and foreign military ammo often give slightly different results.

With USGI ammo, I get 130 fps difference between a 10.3" barrel and an 11.5" barrel, with both M193 and M855 ammo.

Some people claim 250 fps difference from 10.3" to 11.5" with heavy match bullets.

Lost my ticket for a while and found it recently.  They're still taking them but you'll get the RC2.  Below is the pricing information.

They are back in stock now, assuming this is about the 14.5" midlength barresl with low profile gas block.

From DD directly?

If so, nothing in stock.

This is what I was talking about assuming we're on the same page. Select the dropdown for the low profile gas block configuration. https://danieldefense.com/14-5-5-56mm-1-7-gov-profile.html

Cerakote Coyote H-235 rail here against a DDC in the back ground

Looks good!

I might try that on my black MK16 rail.

I was thinking to maybe keep the top of the rail black, but I haven't decided yet.

I guess I missed it. Again

They've been selling out near instantly these last few restocks, this one holding out the longest around ~15 minutes. The good news is that DD has been restocking them regularly, 4 times this year thus far going by my email notifications.

I was able to grab one. The reminder email hit my inbox at 3:10 pm CT and I was able to get it within 10 minutes. However, they stayed in stock until my note above at 6:45 pm CT, so that was a good 3.5 hours give or take.

Thank you, sir!

@beastman  :   Keep checking DD, Primary Arms and OpticsPlanet for DD 14.5 Mid Pinned LPGB SKU 07-077-07308  
              Midway has 2 in stock, $399.99:   https://www.midwayusa.com/product/1021534512

I tried for a second at what would've been 3:45 CST, looking at it now, and was stymied so I assumed they were all gone. Glad either way though.

I got the barrel. Now I just have to wait for the MK16 to come back in stock.

Yep, I’m in the same boat.

This has to fit in here somewhere

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Heck yes! I have 2 tickets and am about to use them!

Jesus christ

Holy chin-weld Batman.

Slick rifle.
Talk about height over bore lol.

Rhodie colors on the lower too.

There was a Geissele MK16 thread in another subforum, but looks like people stopped posting in there.

Nice pic.


Is this an issued gun? If so there's a laser marked rail for all those who were wondering if they got into the field or not.

Yes issued, not mine.

I did manage to snag a MK16 10.5 rail and DD 11.5 barrel at least.

Which upper should I use? Colt Cerro or Mueller dog bone? Leaning toward the dog bone for this one.

Colt upper and lower, DD 14.5 mid length.