Lightweight AR15 Build - CAV-15 MKII Lower & Pencil Barrel

**Emptymag** · May 7th, 2017, 03:24 PM

This build started a year or two ago with the purchase of a GWACS Armory CAV-15 MK II one-piece lower/stock.
I wanted a carbine that was light enough for my wife to shoot as she has physical limitations that make shouldering an average rifle too difficult for her to enjoy shooting. By using the polymer lower (it's made of Dupont Nylon 6) you can shave a full pound off compared to a complete standard lower with stock. Couple that with a lightweight pencil barrel, and I think I can get the weight down to where she can handle it.

I'll add a full parts list at some point, but at the time of this posting I have the following:

CAV-15 lower/stock
Anderson Sport upper (no forward assist/no dust cover)
Tom's Tactical LPK with upgraded Nickel Teflon trigger group
Charging handle
Magpul front/rear BUIS
Faxon 16" mid length pencil barrel

I still need:
Muzzle device
Bolt carrier group
Buffer/spring (I have a standard buffer/spring, but may get a lightweight setup)
Hand guard
Adjustable gas block
Gas tube

This should be interesting. I can't wait to see what this totals out at. I'm trying to make it as light as I can, but there's no way I can afford some of the crazy-light parts that are available on the market, so I'm not trying to compete with $3,000 lightweight guns - I just need it to be "light enough" for my wife.

If anyone has any tips, I'm all ears! If anyone has any questions, I'll answer as best I can.

I never knew a carbine could be so light. My first AR (before I had an understanding of barrel profiles) came with an HBAR, so this thing feels unbelievably light (even assuming it will weigh more once completed) and feels more like a toy.

I just got the barrel yesterday so I slipped it onto the upper/lower to get a better feel for it. Now that it's starting to look like a rifle I want to keep going and finish it, but I have to buy as I can afford the parts.
I'll post up some pics in a sec...

**Emptymag** · May 7th, 2017, 03:34 PM

Here's the heart and soul of a lightweight build - the barrel.
I don't think there's one other part where you can shave more weight than on the barrel.

I went with the highly regarded Faxon 16" pencil barrel. There are others out there, but this seems to be the lightest - without needing to take out a loan.
I picked it up from Faxon directly for $140 (20% off sale) and was $148 shipped.

**Emptymag** · May 7th, 2017, 03:44 PM

Some comparison shots - it's hard to believe how thin this barrel is without seeing/holding it in person!

(birdcage is just on there to protect the threads and to get an idea of how it will look with a muzzle device)

I should have taken the handguards off the other rifle for a true comparison, but most of you know what they look like.

There's the GWACS Armory CAV-15 MKII polymer lower. I will comment more on that later, but if you have questions about them, just ask - it's a pretty neat lower and super light and durable - pretty much universally accepted as the best choice out there as far as polymer goes.

**Emptymag** · May 8th, 2017, 12:50 AM

I had started a thread in the Rifle subforum asking about lightweight bolt carrier groups and how they may affect recoil.

I was considering the AIM lightweight as it's on sale for $89 and I can't justify spending the crazy amounts that other companies want for lightweight BCGs.

I'm not 100% sold on needing a lightweight BCG and started looking at "standard" bolt carrier groups.
My default would be to just get an $89 PSA premium BCG - I have one in another carbine and I've seen mostly positive reviews.
Some other "good" brands start getting crazy with pricing and I would like to stick near $100 if possible.

I see that Primary Arms has the FailZero EXO coated M16 cut BCG on sale for $99.99
I'm not a BCG fanboy so I don't eat sleep and breathe BCG technical details and I get confused by the various "coatings" and what the purposes are for each of them.

A quick search suggests this is a pretty decent product. I have to wonder if this would be a good move to buy this as opposed to the PSA BCG if I decide not to go with a lightweight. The price sure seems right.

Any thoughts?
Any other suggestions for a quality BCG that doesn't break the bank?

**chkrdflg** · May 8th, 2017, 05:30 AM

I have a Fail Zero in one of my builds. It has been fine so far, I don't have a ton of rounds thru it, probably 500-750. Cleans up nice. I got mine from PA for $100 also.

**Emptymag** · May 8th, 2017, 08:38 AM

Originally Posted by chkrdflg

I have a Fail Zero in one of my builds. It has been fine so far, I don't have a ton of rounds thru it, probably 500-750. Cleans up nice. I got mine from PA for $100 also.

Thanks for the input.
I tend to over think things, but when you don't have money to "waste", you want to be sure you're making the right decisions and not end up having to "buy twice".