Lightweight Carbines

AR/M4 AR General Discussion
1

I’ve been toying with the idea of getting a lightweight upper, if not a new carbine entirely for some time. Right now funds won’t allow it (Ammo is pretty expensive;) ) but I’d like to have a framework for what I’d want.

Here is what I was thinking of so far:
A1 upper receiver
1/7 14.5 pencil barrel with perm. Phantom
6 pos. M4 stock
CAR hand guards
Hogue grip
Side sling mount
BFG Vickers sling

This carbine would be a “survival tool” that could be used for extended periods of time without concern for damaging optics, replacing batteries, or anything beyond loading, aiming and squeezing the trigger. As such, I think it would only make sense to help it blend in a bit better with my area by using either OD furniture or by going the expensive way and doing a camo job.

Right now I don’t have any bare-bones carbines, both are M4’s, one has an Aimpoint, an MI rail system with the KAC covers and grip, and a BUIS. The other has a 13.2 LaRue rail (which I think would only lead to an inability to properly clean underneath the rail since I doubt I’d be packing a strap wrench everywhere) and MI front and rear BUIS’s as well as an EOtech and KAC grip. Neither of these rifles is really lightweight, and I think the optics are nice but I can easily see them getting damaged or fractured to the point of no real use, other than occluding your irons.

That’s what leads me to the A1 upper. Its simple, and can’t be accidentally adjusted or messed up, plus its durable. Irons don’t break or need batteries as well.

Finally, my reason for keeping it light is that in such a situation, I’d want a carbine that is least intrusive to my movement as possible. That means small, and light. Since I’m not willing to go NFA or contend myself to short range ammo effectiveness I’d go with 14.5 barrel with an effective FH for 16" overall.

What are your ideas and tips for lightweight carbines? (Not necessarily for “survival” uses.)

2

I’ve had two lightweight barreled guns, a Colt preban and a Bushmaster lightweight, in similar configurations (A1/C7 upper), and the one thing I noticed and didn’t like was that when the gun got heated up, the groups shifted more than I liked. When mine got hot, instead of keeping all shots within a 4-6" circle at 100 yards, it was more like a 8-10" oval at 100 yards.

I won’t go any lighter than an M4 profile. That extra thickness forward of the FSB seems to keep the shooting within a 4-6" circle at 100 yards.

My no-frills lightweight gun is the following:

Bushmaster 1:9 M4 14.5" with permanent Phantom
Bushmaster A1/C7 upper (with A2 rear aperture and front post)
Cavalry Arms CAV15A (the aluminum one) lower
Magpul CTR
Cavalry Arms C4 handguards
Defensive Edge lower parts kit
CMT charging handle and bolt carrier group
Side sling mount and Vickers sling

It’s somewhere between 6.5 and 7 pounds, I think.

The barrel is probably the most accurate carbine barrel I’ve ever gotten. It’s been reliable too when I’ve heated it up.

A2 aperture gives me less windage adjustment, but the big 0-2 hole is nicer than the A1 sights for close up. The A2 front post is for ease of adjustment, since keeping up with an A1 sight tool in an A2 world it PITA to me.

The CTR is my favorite carbine stock. It’s priced well, comes in colors, has solid lock up, allows me to use most slings, and has that nifty non-slip buttplate.

The Defensive Edge lower parts kit has been very good. The trigger smoothed out nicely with use.

3

My Lightweight gun started out as, well a Lightweight Sporter Colt. flashsuppresor, no bayonet lug, A2 upper.
I replaced the solid A2 stack with a Colt 4 pos “car” stock, teh new ribbed ones wern’t out yet.
Replaced the CAR handguards with GI M4 handguards
trijicon front sight
GG&G slic mount with a Surfire classic on the left side and aswivel on teh right
Boonie packer 2 point sling
Tango down grip, got it for 10 bucks, otherwise I’d use an A1 grip
That about it, it doesn’t get shot much these day’s though.

As far as the A2 sight, I think the A1 is a better sight, but I don’t worry about it. I just bottom it out, before I zero. I don’t intend to use, or care about, the range knob, so all I have to do is insure its bottomed out, and the windage lines up with the hash marks(paint).

I may change out the light for an even older school surefire though.

Bob

4

I’ve only had formerly owed two lightweight carbines before, a Colt (model R6420) AR-15A2 Carbine SP2 with A1 upper, 2 position CAR stock and a Colt (model R6530) “Sporter Lightweight” with A2 upper and solid A1 size stock with A2 buttplate.

I actually used my Sporter Lightweight carbine during the '92 L.A. riots when I was living there at that time, I got other ARs at that time but my lightweight was the only one with me because I practiced with it a week before the riot at a private gun range which I was a member.

The big advantage of the lightweight carbine is that it could be carried for a long time, I carried mine for three straight days, took a nap with it while my father and brother-in-law rotated guard duties.

The negative side of the lightweight barrel is that it would heat up quickly during very high volumes of rapid fire and when hot groupings spread wider and mostly in the upwards direction.

Here’s my idea of a lightweight carbine (YMMV):

A1/ C7 upper receiver (I prefer C7 type because of the brass deflector)
1/7 14.5" lightweight, midlength gas system barrel with perm. Phantom model 5C1
6 pos. Magpul CTR or solid Colt A1 “CS” marked stock
Daniel Defense Lite series FF or MI rails hand guards
A1 or Magpul MIAD grip (with the smooth - no finger grooves front strap)
Daniel Defense offset side rail sling mount
BFG Vickers sling

My reasons between the difference on your list:

Upper - I prefer the C7 type A1 because of the brass deflector in case you have to shoot from the left side, I would also consider a flat top M4 upper with a Troy BUIS so I could use, detachable A1 carry handle and optics (and just remove optics with QD mounts when damaged and use the BUIS).

Midlength lightweight barrel - smoother more reliable action.

Phantom model 5C1 FS - no bottom slots to lessen dust signature when firing prone, the smooth front end will lessen snagging things.

Magpul CTR stock - very solid compared to a standard M4 but if a stronger stock is required the new version A1 is stronger than the collapsible.

Rails handguard - it keeps the barrel cool and you could either attach your light to it or take everything off, it’s more flexible than std handguards.

Grip - I personally don’t like grips with finger grooves and I learned that when I was doing USPSA-IPSC pistol competition in the '80s, if you’re in a hurry and grab a grip with finger grooves usually you grab it at the wrong place and have to loose some time before you could adjust your grip.

My current carbine now is a LMT 16" M4 barrel Defender 2000 with LMT M16 BCG, KAC M4 RAS rails, KAC VFG, Surefire M951C weaponlight, Magpul CTR stock, Magpul MIAD grip, KAC 300m BUIS, EOTech 551 on LaRue QD EOTech mount and Blue Force Gear Vickers sling.

5

I wouldn’t permanently attach anything to the muzzle. Either SBR it or get the 16" barrel.

I’d use M4 handguards instead of regular carbine handguards. The double heat shields keep the heat away better and the larger diameter is more comfortable to me. Keep in mind though, a DD 7.0 is virtually the identical weight to M4 handguards, FYI. Obviously rail covers and VFGs increase this weight.

I’d figure on some kind of way to have a QD light attached. The Surefire mount for G2 lights is my preference as the light can come off and do handheld duty as well.

I second the idea of the A1 grip. Use a gapper with it though.

Consider a tritium front sight post. I just bought one for one of my iron sight carbines and I like the look of it so far.

The bottom rifle in the pic below is my 16" version. The 11.5" on top has since been modified to match the 16".

6

I am a huge fan of the A1 upper. They are battle proven to be extremely tuff. They hold up well to field conditions of being banged around. I run them on my personal guns. I shoot iron sited A1’s out to 850yds. Durability and simplicity in one great package.

7

RobS-

Could you please tell me more about this mount:

“The Surefire mount for G2 lights is my preference as the light can come off and do handheld duty as well.”

I’m looking for something like that for use on my work gun, which has standard handguards and no real good way to mount a light. Interested in any info you might have: pics, prices, part number, etc.

Thanks in advance.

-Bryan

8

This mount (get the M79 for a G2 light)

attached to a piece of rail like this

bolted to the handuard bottom.

get yourself a light like this with the Z32 bezel and Z49 tailcap

and for $138.50 you’ve got yourself a weapon-light mounted to your plastic handguards that you can remove and use as a handheld light with your handgun or other uses.
(hopefully grant doesn’t mind me stealing his images/links)

The other option would be to get yourself a TACTICAL ILLUMINATOR MOUNT from Brownells which allows you to mount the rail virtually anywhere on the handguard (be careful, you’ll have to trim the screws and drill holes in the handguard) as opposed to just on the bottom of the handguard.

9

Thanks Rob. That’s good & helpful info.

10

that makes me a little nervous
I just built up a lightweight with a RRA lower and bushmaster lightweight upper w/16 pencil barrel

I haven’t got to really run a bunch of ammo through it and I was a bit concerned about the barrel heating up and the group opening up…
but, I wanted it light for a few reasons (wife and son’s being able to handle it as well as for me out walking on the occasional hunt)

guess I will just have to put it through some paces and see

11

I hear the “groups open up after sustained fire” argument all the time. I still can’t figure out who’s using hyper-accurate sustained fire over long periods of time and long distances.

My “pencil” barrels have served me quite well through various training classes and competitions. Admittedly, I’ve never done a Beta-mag dump and then checked the accuracy though.

12

After 56 rounds in about 3-4 minutes, I can no longer keep all shots within a 6" bull at 100 yards with the lightweight barrel. I don’t know if the barrel gets so hot that it droops ever so slightly, causing the POI to shift downward, or what.

I don’t have this issue with M4 barreled guns or A2 gov’t profile guns.

13

Heavy bbl’s heat up and shift POI, it just takes more rounds fired. But, remember, HB’s take longer to cool than pencil bbl’s. Infact, I’d guess almost twice as long. Just something else to think about.

14

Me too. Cannot decide between a flat-top with an optic, getting an optic for my Bushie M4forgery/A2 upper, or springing for a classic SP-1 carbine on GunBroker, etc.

I had one of the latter, and foolishly sold it after just before Y2K. Serves me right for being greedy.

.

15

If you decide on an optic, I’d go with a flat top upper. :cool:

16

This is my idea of a lightweight fighting rifle/carbine:

17

My “light-weight” go-to HD carbine.

  • BM A1/C7 upper
  • RRA lower
  • DPMS16” LW barrel w/ A1FH
  • SF Classic weapons light mounted w/SF M14 mount

18

Alright then, here’s mine

19

20

You might be amazed at just how un-lightweight that detachable carry handle is.

I’ll betcha that your rifle, as pictured, weighs more even than this one