11.5" CQBR Build


June 9, 2011, 01:08 AM
Last year, I determined that I needed a another SBR as a better training rifle. My 7.5" PDW build was fun and has so far been very reliable, but it's not terribly practical rifle when compared to a longer, more universal carbine. The goal was to have a rifle primarily for CQB use, but that could also still perform at range.
I also wanted a rifle that could be a Trunk Gun for work, if necessary.
So, I started planning my build:

LaRue billet lower
Daniel Defense 11.5" CHF barrel w/ LPG
Daniel Defense AR15 LITE 10.0 rail
BattleComp 1.0
TangoDown grip
TangoDown stubby QD VFG
Daniel Defense LPK
RainierArms Thunder Bolt BCG
BCM Gunfighter Mod.4 (medium latch)
Sprinco extra power recoil spring
H2 buffer
Magpul BAD Lever
Aimpoint M4S w/ LaRue mount
VTAC light mount
SureFire G2X Tactical
TangoDown SCAR rail covers
BlueForceGear Vickers Padded QD sling

Finally, I got all of my NFA stuff in order and then got my lower engraved; so away I went and this is what I came up with:










And here it is with "the rest of the family":


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Sam Cade
June 9, 2011, 01:46 AM
Top notch sir!

June 9, 2011, 01:47 AM
nice build...but may i ask, whats the point of a nice big quad rail if your just gonna cover it all up?

Sam Cade
June 9, 2011, 01:50 AM
nice build...but may i ask, whats the point of a nice big quad rail if your just gonna cover it all up?

He has a front sight, VFG, flashlight and sling mount on it. :rolleyes:

June 9, 2011, 11:23 AM
Top notch sir!
Thank you sir.

nice build...but may i ask, whats the point of a nice big quad rail if your just gonna cover it all up?
Any non-used space gets a rail cover to help protect my hands against heat. The rail covers are heat resistant, so if I heat the gun up, I won't have to worry about heat radiating onto my hands and causing issues. They're also to protect the rail against damage during impact or abuse.

He has a front sight, VFG, flashlight and sling mount on it.
What he said. :)

June 9, 2011, 11:31 AM
but may i ask, whats the point of a nice big quad rail if your just gonna cover it all up?

Because some of us like to actually shoot them, not just look at them, and those things get HOT.

June 9, 2011, 07:03 PM
im not questioning the heat protection but it seems like you could attach the few things you want on their without having a large heavy quad rail plus the width of the cover when you could do something like this and have it be lighter still
just add rail sections where you need them and voila


but its your build and thats all that matters in the end :)

June 10, 2011, 03:38 AM
CAR handguards are pretty much worthless. They basically only serve to keep your hands off the barrel. The handguards are antiquated 80's technology that only marginally works.

Heat- They heat up really bad when you start pumping out rounds. I can go about 60 rounds of rapid fire before I need to put on gloves, since the handguards heat up so fast and hot. Rail systems have venting holes, so they allow better heat venting for cooling. Free-float systems also do not have heat transfer from contacting metal like the barrel or gas block, and instead get heat transfer from radiating heat. That heat is much less significant and slower to transfer. Rail systems tend to be significantly cooler during extended fire.

CAR handguards are not designed to have rails, and they're not designed to have stuff mounted on them. They have rails for that. There is a reason why the M1913 rails are called "Picatinny" rails. They were standardized by the military. There is also a reason why rail systems are so prolific within the military, as well as in law enforcement and government agency work. Buy something that's purpose-built for your implementation.

Weight- the weight difference is negligible. 12.1oz for the AR15 LITE 10.0 rail. The CAR handguards are around 10oz with all mounting hardware. Add weight onto that for the extra rails you bolt on.

Accuracy- many rail systems are free-floating; meaning that they do not rest on the barrel. CAR handguards require the use of a the delta ring assembly and the front mounting bracket. Whenever you have something touching the barrel, you open up room for barrel deviation. If you push or pull on the handguards, it will subsequently push or pull against the barrel. This causes barrel flex and deviation, which affects long-range accuracy. Additionally, this causes heat transfer from the barrel and gas block onto the handguards. Free-floating eliminates these issues.
Note: There are free-floating CAR handguards, but those are made specifically for Match use in Service Rifle competition shooting.

Rigidity- Rail systems are, for the most part, very rigid and strong. You have an exceptional Return-To-Zero (RTZ) capability for optics and accessories. This is made possible by the standardization of the M1913 rail specs, but also due to the mounting systems that the rail systems use. CAR handguards are not rigid; in fact they tend to rattle a lot. Rail placement and mounting on CAR handguards are also not "true". They may be canted off to one side or the other. You have no guarantee that the rail will be in the same location when you remove and reinstall the handguard. This is particularly important for aiming modules like AN/PEQs and ATILLAs.

It's basically old vs new. 1983 Ford 4WD vs 2012 Audi Quattro AWD.

The rifle is purpose-built, and there's absolutely no reason to put CAR handguards on it. Build your rifle to suit your use- don't half-heart it and just slap non-native components on and say "it's just as good", because it's not. From an operational perspective, there is a world of difference.

Just to add to this, one of the things I do is advise LE agencies on making their purchases when they upgrade or modify their existing ARs, as well as advise them on what they need to know if they don't have ARs yet. I have seen a lot of agencies getting rifles with standard CAR handguards as a cost-cutting method. They will then eventually put on an aftermarket mounting rail or bracket to attach to the handguards, and every one of those systems has problems. More and more officers and agencies are ditching those handguards and installing railed handguards (like the Daniel Defense EZ CAR, or the SureFire M73) pr free-floated railed forends for better utility. The move in the professional realm is to move away from the standard CAR handguards.

June 10, 2011, 07:46 AM
what muzzle break is that? i really like it

June 10, 2011, 11:45 AM
BattleComp 1.0. They're fantastic. The recoil reduction is outstanding, and they're very small/compact.


RainierArms.com is one of their retailers. They also have stainless, and they have longer ones for pinning onto 14.5" barrels as well.

Sam Cade
June 10, 2011, 04:14 PM
BattleComp 1.0. They're fantastic.

x2 on that.

June 13, 2011, 11:00 PM
Took the M4CQBR to the range today. 250rds in about an hour with flawless functioning.
This is my new favorite rifle!









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