I just bought a Cav Arms MkII lower on sale today for $90 bucks for my next build which I’ve decided is going to be a lightweight build. Contemplating 9mm or .223. What I want to do is get a 14.5 LW upper special from BCM with the AX2 flash hider perma-attached and swap out the upper for a Bushmaster Carbon15 stripped upper. I’ll be using MOE handguards. Anyone have a Carbon15 upper or have heard of one ever going KABOOM?
I would think that you would be better served by an aluminum upper and sacrifice a little wieght for an increased safety factor.
Here is a link to one story. http://www.calguns.net/calgunforum/showthread.php?t=70654
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I was thinking about this earlier and started looking for other aluminum choices like the DPMS or Les Baer slick side upper without the forward assist or brass deflector. Any know the weights of these two receivers stripped? Any know if BCM has any 9mm or slickside, flat top uppers?
Try ADCO Firearms. You can buy a Rock River Arms 9mm upper, strip the 9mm brass deflector off, replace (or don’t) the dust cover assembly, have ADCO drill a hole for the 5.56mm gas tube and your G2G. Kind of a pricey option though… 160 or so out the door… but it’s light & slick!
Are you going to run optics or irons?
I’ll run the FSP with Magpul rear BUIS, a DD lightweight Aimpoint mount and a Primary Arms Gen 8 w/ killflash.
Just recently, decided to go with a BCM 14.5 lightweight middy with Battlecomp perma-attached and Magpul MOE handguards.
You can also purchase Les Baer’s standard upper without FA for 112 + ship. Fits tight - usually needs a little fitting (no big deal), but a cheaper option and lightweight.
ALSO, I believe you would need to purchase a carbon barrel extension and properly headspace (may require a proprietary tool for the extension - not sure) if you wish to use a carbon upper. Makes things a tad bit trickier and expensive.
The Carbon-whatever is marginally reliable at best.
Invest in a truly quality upper and you would be better served, IMO.
Sun Devil Mfg also has a slickside billet upper with dust cover and no FA, with their LE/mil pricing its under 100.00 and light as all get out.
I had 2 BM factory build carbon AR15s and they sucked. Accuracy was crap, and one would not feed. I sent that one back and BM fixed it, to their credit. Perhaps you can custom build a reliable gun starting with a carbon stripped upper, but I would stay away from the factory ones for sure. And for a few ounces more, just get one of the excellent pencil barrel uppers currently available and experience excellent reliability…
I’ve been around 3 of the carbon uppers and they all sucked. Go aluminum. Have you considered a Troy Ext 9" rail with Magpul BUIS’s front and rear? That FSB is heavy.
The FSB is heavier then the TROY, including the weight of the base + a magpul midlength moe? Does anyone have the weight of this combo?
Looking forward to how this turns out.
I have wanted to buy one of these lowers the price and weight is awesome. Have you finished up your build?
Need some help with the lower build. The safety selector setup is different or reversed. Does the upper hold the spring and detent in place on the Cav Arms lower? Also, the hammer pin is too short. It fits flush on either one side or the other and the other side of the hammer hole isn’t secured to the receiver.
You put in the spring and detent in from the top and then hold the detent down with a dowel/punch/whatever and then install your safety. To remove safety after intallation, move safety in between Safe and Fire and push out. You may need to clip a coil or two off of your spring.
Using a punch, push the hammer pin in until it is caught by the spring inside the hammer in the notch in the center of the pin. The reciever area around the Hammer pin hole is thicker than on a mil-spec aluminum lower, and your hammer pin, when properly installed, will be “counter-sunk” on both sides of the lower. Be careful and do a function test after this is installed as when I put together my first Cav Arms lower, I did not and it immediately doubled at the range until I noticed my mistake.
Did you receive the instruction sheet with the buffer retaining pin roll pin taped on it? That’s how they used to send them out, I’m not sure if dsg arms does that or not.
In any case, here are the assembly instructions from cavarms:
http://www.cavalrymanufacturing.com/CAV15/CAV15MKIIinstructions.html
When I assembled mine, I used stag lpk’s. I had to cut the rims off the safety detentes to get them to fit in the hole, and on one of the builds I trimmed the spring a bit. I also had to chase out the holes for the buffer retaining pin roll pins. I also did some filing to get pmags to drop free.
This did the trick, thank you! Yea, I received the instruction sheet with the roll pin. I had to go back and read it again but sure enough it said exactly what you stated. I didn’t have to modify anything on my lower build to get it all to work, I’m just missing a few more small parts like the bolt catch roll pin.
Here’s how the lower for a .22lr upper turned out…
Looks great. How does it balance and handle?