Quest for the Ultimate AR15 SBR Upper

blaxsun

blaxsun

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As much as I love my 7" PDW, I find it's a tad on the heavy side - so I'm on a quest for the Ultimate SBR Upper. As such, I'm looking for recommendations. Here's the criteria:
• 7"-10.5" barrel length (maximum)
• DI or Piston, Chambered in 5.56
• Lightweight rail system
 
MK18 Mod 1 upper.

RIS II rail.
DD 10.3 CHF 5.56 1/7 Barrel
FA BCG
BCM Gunfighter GenII CH
Knights BUIS
Muzzle device of your choice

Its DI, its light... The gas port is sized for reliability (functioning)
Paired with a H, H2 or ST2 buffer, its a great SBR upper.
 
DI for sure, piston is only going to add weight.

All the 7.5" barrels I've ever seen are heavy profile so that would be your main culprit. Try to find a .625" 10.3" barrel. A real Colt one would be ideal, but DD makes them too. I personally prefer the A2 FSB but you could lose some weight by going with a micro gas block.

For a rail I'd use a DD M4 9.5FSP, still one of the lightest rails out there, but their's a ton of options. Magpul MOE are nice and light.
 
Hilo71 said:
MK18 Mod 1 upper.

RIS II rail.
DD 10.3 CHF 5.56 1/7 Barrel
FA BCG
BCM Gunfighter GenII CH
Knights BUIS
Muzzle device of your choice

Its DI, its light... The gas port is sized for reliability (functioning)
Paired with a H, H2 or ST2 buffer, its a great SBR upper.
Click to expand...

+1 on the MK18 Mod 1

I have one and love it! cant go wrong with USSOCOM stuff ;) If you dont want to build it up yourself i know High Caliber Sales in the states makes a complete upper (http://highcalibersales.com/mk18-mod0mod1-carbine-upper.html) for a reasonable price.

Cool video of their upper in action http://www.youtube.com/watch?v=U5kuhLU6YZk
 
I'm doing my PDW build off of the 300BLK barrel (9"). It's quite the Frankenbuild at this point...I'd like to top it off with one of those NEA collapsing stocks but for now it'll wear a Magpul UBR. Hopefully by the end of next week I'll have the rest of the things I'm waiting for...
 
b_w. said:
I really like my 10.5 LMT...runs like a champ
Click to expand...

They have an excellent reputation but they're thicker than a normal government profile, more like .740 under the handguards, whereas a government profile will taper from .675 to .625 or so.

I saw a post where a fellow had an LMT 10.5" and a Colt 933 11.5" lightweight barrel which measures .625" at the FSB. He didn't have a scale but said the LMT upper felt heavier to him. Surprising considering it's an inch shorter.

I tried to find weights of different barrels online but no one seems to list the weights like they do with quadrails, you'd think it would be info that's in demand.

If I were looking to build a lightweight SBR I'd be taking a long hard look at the weight of everything. Stocks for example, no one normally pays too much attention to the weight but an LMT SOPMOD weighs 11.5oz and an old Colt CAR stock is only 4.4oz, that's almost 1/2lb difference in just the stock.
 
I'm getting a PDW built with a 7" Noveske NSR rail. If you want to bolt a whole bunch of stuff to the rifle, then the NSR probably wouldn't be for you since the accessories aren't readily available yet. There are rail sections for the keymod slots, but that kind of defeats the purpose of the NSR rail (to save weight).

I don't really need to bolt anything to my rifle, so I figured it would be a good choice for the weight savings and LCF.
 
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