Assembling a Lightweight Carbine

[tinfinger]

I want to assemble a lightweight defensive carbine and would appreciate any input. My requirements are 1x7 twist, ability to cowitness a red dot or holosight, iron sights, and weapon mounted light. Cost is a factor, so marginal weight savings at significant cost probably would be out. To me, this drives it towards the KISS mode.

I can get a good deal on a RRA lower with two-stage trigger and CAR stock, so I’m probably going to use that as a starting point. For a CAR upper, I’m leaning towards either


1. finding a Colt 16” pencil barrel
2. CMMG 14.7 with permanent flash hider
3. RRA CAR A4 upper with a 1x8 stainless barrel, although it would not be a pencil barrel. (Are there pros/cons I should be aware of on a stainless barrel?)

I believe Sabre makes 1x7 uppers but I don’t know if they make a lightweight or are readily available. The Colt would have a carry handle, so I would use gooseneck mount for optics – bad idea or acceptable? Any of the others, I would probably get a flattop with a BUIS.

I see no need for a rail system if I attach a light to the front sight. Good idea or bad idea?

Any further suggestions?

[Snake RAH]

One question: are you married to the idea of a match trigger on your build? Personally, I don't recommend match triggers on fighting guns.

1x7 isn't a priority of mine, so if I was going lightweight, Bushmaster pencil barrels are easy to find. BM will put that barrel on a flattop upper, and you now have a complete upper. The downside is that you may have to use a taller front sight post if you go with a rear sight like LaRue, LMT, Troy, or some of the other military height rear sights.

Stainless would require you to have someone like Randall or ADCO to spin the barrel down to a lighter profile. That's additional cost that, in this case, could be saved towards your red dot, light, ammo, or training.

[RWBlue]

I have a 16" bushmaster lightweight barrel on my home built rifle. I think it is a 1x9 twist. I like it for what I am doing.

I think Noveske has a 16" lightweight 1x7 barrel for sale also. (I am thinking this may be the most accurate setup.)

As I understand it CMMG has a 16" and 14.5" lightweight barrels. ( I don't know the twist.)

I am curious as to what you end up with.

[rob_s]

If you're cost sensitive as you say, then stick with the CMMG. I'd get the CMMG 14.5” Lightweight CAR Upper w/Permanent Phantom and .625" FSB and stick a Surefire forend on it (they don't have the Surefire listed as an option).
http://cmmginc.secure-mall.com/shop/?shop=1&cart=659448&cat=27&

If I wasn't as cost sensitive as you (and I guess I wasn't), I'd build this and stick a smaller/lighter light on it.

http://216.77.188.54/coDataImages/p/Groups/196/196030/folders/171062/1926930ARComplete.jpg

[tinfinger]

I'm not married to the two stage RRA trigger...I can get into one in a good price and figure why not. I didn't think the RRA trigger was particularly light?

Rob s, like your carbine. I am just looking for a more basic outfit; maybe later I can add more bells and whistles as I may figure out which I like.

I kind of don't get the quad rail setups. If you can put a sight on the flattop upper, and a light on the front sight...why does everyone go with quad rails? Now, I see if you have a big light, it might be nice to mount it further aft, closer to the center of gravity. And if you like a VFG.

[rob_s]

I chose mine for a variety of reasons. I wanted a flipup front sight, the standard A2 front sight base was not "F" so the BUIS woudn't work, I wanted the longer rail to cover more of the barrel to protect me from the heat, the rail adds virtually no weight compared to the M4 handguards & delta ring, I wanted to keep the front sight and taper pins just cut down and hidden under the handguards, I wanted the light to be QD, I thought I might eventually add a VFG (which I have since added), I wanted a two-point sling (not shown) to mount at the barrel nut, and I didn't want any outside pressure causing the lightweight barrel to bend (hence the free-float).

With that said, if you don't need any of that, you can just buy the CMMG complete barreled upper with bolt, carrier, charging handle, and handguards for $575 and mate it up to your lower.

[tinfinger]

Thanks Rob S, that sheds a little light on the subject for me!

[Sam]

I'm not married to the two stage RRA trigger...I can get into one in a good price and figure why not. I didn't think the RRA trigger was particularly light?



The two stage trigger is pretty light, I think they claimed 3 - 3.5lb, but they felt lighter to me. Like the other member posted earlier, I agree that you don't need a match trigger (read = light) on a fighting gun. Larry Vickers doesn't recommend light trigger either, I listen to him.

[graffex]

The two stage trigger is pretty light, I think they claimed 3 - 3.5lb, but they felt lighter to me. Like the other member posted earlier, I agree that you don't need a match trigger (read = light) on a fighting gun. Larry Vickers doesn't recommend light trigger either, I listen to him.

Nothing wrong with getting a nice 2 stage trigger on a fighting gun. That said if you want a match trigger on a fighting gun spend the money and get a Geissle trigger, you wont regret it. That's the only aftermarket trigger I would put on a fighting gun.

[Luckystiff]

I put together a light weight KISS carbine like what you are describing. Here is what I used:

1. Colt 16" pencil 1x7 cut to 14.5 with a Vortex pined to the front done by KKF.
2. PWA Lower with an old Colt M4 stock.
3. BM A1 upper
4. Colt standard carbine handgards.
5. Surefire classic light with mount (#649 kit)
6. Trijicon night sights.

This rifle is so light and handy, everyone loves it. I plan on putting an Aimpoint M3 on a goose neck some day. If you shop around you can find most of this stuff used and save some $$.

[RWBlue]

I kind of don't get the quad rail setups. If you can put a sight on the flattop upper, and a light on the front sight...why does everyone go with quad rails? Now, I see if you have a big light, it might be nice to mount it further aft, closer to the center of gravity. And if you like a VFG.

I can't tell you how others got to quad rails, but I can tell you how I ended up wanting quad rails.

I started off with an A2 HBAR. When shooting longer ranges, I found out that I could push or pull the barrel enough (tight sling or bipod) to make a difference. So I wanted FreeFloat.

When I built my next rifle I went with a FreeFloat quad rail. I have since pushed the EOTech forward onto the rail and added a Verticle grip.

I assume that the fast light guys have their quad rails full with:
Light, VG, IR enhancer/IR laser, EOTech or AimPoint, then on the reciever Night Vision or 3x optic.

[tinfinger]

Pardon if this is a silly question, but freefloat handguard rails are stable enough for optics? Interesting.

[RWBlue]

Pardon if this is a silly question, but freefloat handguard rails are stable enough for optics? Interesting.

IMHO, Yes for EOTech, yes for scout scope (Leupold 4x Extended Eye Relief), no if you are trying to do a split mount between upper and rails with a high magnification scope.