7 lb 9.7 oz Varmint AR with 20" BBL & optic

[Warg]

After having sucess with the "AR Mountain Rifle" builds, I decided to see if a lightweight varmint hunting AR was possible. The goal for this rifle was sub-8 lbs with the optic. I wasn't sure this was possible given the last varmint rifle I built weighed almost 12 lbs.

http://i304.photobucket.com/albums/nn176/Dr_Wolfenstein/204%20Ruger%20ARs/DSCN1928_sm.jpg

http://i304.photobucket.com/albums/nn176/Dr_Wolfenstein/204%20Ruger%20ARs/DSCN1926_sm.jpg


The majority of the weight savings came from the following: Dimpled WOA barrel (3 lbs to 2 lbs 5.9 oz); FF HG (7.78 oz with BBL nut); VLTOR Modstock (6 oz in A1 length w/o cheek pods); JP bolt carrier (6.49 oz); JP rifle buffer (3.2 oz); stripped LB upper (6.9 oz).

Upper parts:

WOA 20" .204 BBL, 1:10 twist "Light" HBAR profile & dimpled by Marvin Pitts
Les Baer Upper w/o FWD assist
BCM Firing pin, retaining pin, cam pin, BBL nut
AP Customs 15" CF tube
BCM Mod 4 CH
VLTOR low profile SS clamp on GB
JP low mass BC
Palmetto St Armory bolt


Lower Parts

AA Stripped lower
G&R LPK
MOE grip
VLTOR Modstock Clubfoot Rifle stock, A1
Rifle buffer tube
CS Rifle buffer spring
JP low mass buffer
Geissele SSA-E trigger


Optics and Misc

Nikon Monarch 5-20x44
Cerakote Coyote tan, FDE, Federal Brown
Millet Scope mount
Many different 20 rd mags from NHMTG, D&H, & Magpul


The optic was a spare I've been using for quite some time. I was going to upgrade to a lighter scope (this one is 19 oz), but after seeing the final weight of this build, I'll probably stick with it for a while. The glass is clear and I really like the parallax adjustment on the side.

Some pics of the Carbon Fiber FF tube, barrel, etc.

http://i304.photobucket.com/albums/nn176/Dr_Wolfenstein/204%20Ruger%20ARs/204barrelbeforesm.jpg
This is White Oak Armament's light HBAR profile. It tapers from 0.95" to 0.84" dia behind the GB, 0.75" at the GB and 0.74" to the muzzle. The BBL is not listed on their site, but you can call to order it. Figure about 6-10 wks. They told me it was 2.5 lbs, but obviously that was a bit optimistic.

http://i304.photobucket.com/albums/nn176/Dr_Wolfenstein/204%20Ruger%20ARs/DSCN1637_sm.jpg

http://i304.photobucket.com/albums/nn176/Dr_Wolfenstein/204%20Ruger%20ARs/DSCN1845_sm.jpg

http://i304.photobucket.com/albums/nn176/Dr_Wolfenstein/204%20Ruger%20ARs/DSCN1848_sm.jpg
Marvin removed 10.1 oz!

http://i304.photobucket.com/albums/nn176/Dr_Wolfenstein/204%20Ruger%20ARs/DSCN1683_sm.jpg

http://i304.photobucket.com/albums/nn176/Dr_Wolfenstein/204%20Ruger%20ARs/15inchHGweightsmwoBN.jpg
Weight of 15" HG with barrel trunion and mounting hardware, but without factory BBL nut required for installation. Total with the BBL nut is 7.78 oz.

http://i304.photobucket.com/albums/nn176/Dr_Wolfenstein/204%20Ruger%20ARs/DSCN1693_sm.jpg

http://i304.photobucket.com/albums/nn176/Dr_Wolfenstein/204%20Ruger%20ARs/DSCN1873_sm.jpg
Here you can see how the barrel trunion for the HG mounts over the BBL nut. This locks up pretty solid and the HG appears to be robust. The weak link are the HG mounting screws- only three. This will be fine for hunting, but is likely ill advised for use on a defensive firearm.

http://i304.photobucket.com/albums/nn176/Dr_Wolfenstein/204%20Ruger%20ARs/DSCN1874_sm.jpg
Painting the BBL in this manner was a PITA.


http://i304.photobucket.com/albums/nn176/Dr_Wolfenstein/204%20Ruger%20ARs/DSCN1930_sm.jpg
Weight without optic and mount.


http://i304.photobucket.com/albums/nn176/Dr_Wolfenstein/204%20Ruger%20ARs/DSCN1929_sm.jpg
Total weight. Goal met.

Like many of my recent builds, I haven't even had time to shoot this due to extensive travel demands for work. :mad:

More later...

[a0cake]

Really interesting. It's not something that I would ever consider building for my own purposes, but that's the beauty of the AR. No matter what the intended purpose, you can "have it your way." I'm sure you'll have a lot of fun with it. Nice job.

[0reo]

I'm curious to hear what you think of the JP bolt carrier group.

Nice looking rifle.

[dpaqu]

I would not have the heart to paint that CF float tube.

[Warg]

I would not have the heart to paint that CF float tube.

The reason for painting is due to the lack of any indigenous carbon fiber plants in the desert or high plains where I hunt. :p

Seriously, the CF tube isn't much $ compared to the scope or BBL so that wasn't too bothersome.

[Belmont31R]

How does it shoot?

[Warg]

How does it shoot?

Dunno yet. This will be my first full weekend home in five weeks. If I can take care of some chores I'm going to try to get it to the range.

After boresighting I am a bit concerned about the A1 length stock. I might have to fab a rubber pad or switch to an A2 as this one seems a bit too short.

[Warg]

I'm curious to hear what you think of the JP bolt carrier group.

Nice looking rifle.

Thanks.

I've used the JP carriers on two other rifles and have spent a lot of time tuning by swapping buffer springs and buffers. These seem to work fine if you're using a rifle length spring with a midlength gas or longer (even with an A5 RE & buffer). I noticed cycling issues (too much gas pressure for the lightweight carrier) using a carbine length spring and carbine length gas system on another build. My experience is with 5.56 and .223 ammo. I think the .204 will be very similar based on the last one I built and tested.

[usmc1371]

Man that thing is bad ass. My LBC .204 is a tank its got to be over 12 pounds with scope. I really like the look of that dimpled barrel.

[SilverTongueDevil]

Sweet I am looking at doing something like that myself for varmint hunting.

[MustangGreg66]

I don't ususally like the dimpled barrel look, but that looks pretty good. And being able to actually see the weight savings is cool.

[soco_27]

Very nice build..i agree with everyone about the barrel, nice touch..Let us know how she groups!

[ThreeFingerPete]

That's a killer build! I like it man, thinking outside of the box.

[Blstr88]

Wow I love everything about that rifle, great build!!

[SicTransit]

I feel like I need that gun. Outstanding build.

[soco_27]

Any update on performance and grouping?

[blasternank]

Any update on performance and grouping?

I'd like to hear about this as well!

[N8rfastback]

That thing is awesome! I wanna hear how it groups too.

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[2theXtreme]

That is a sweet looking rig there sir! Off topic...where did you get that scale? I have been looking for a digital scale like that but can't seen to find one in stores. Thanks.


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[hunt_ak]

That is a sweet looking rig there sir! Off topic...where did you get that scale? I have been looking for a digital scale like that but can't seen to find one in stores. Thanks.


Sent from my iPhone 4 using Tapatalk
Look in the kitchen section of any store...they sell food scales just like that...

Cool build. Are the dimples a different color than the rest of the barrel? In the first pic, it is hard to tell but appears that way farther down. If so, how did you do this?

[Warg]

For the others asking about groups- yes it shoots well. I'm getting less than .75" groups (5 shot) at 100y with Hornady 40 and 45 gr VMAX. For some reason, the barrel does not perform as well with the 32 gr stuff as my best group so far is 1.1". I've some handloads I'll be testing soon as well.


Look in the kitchen section of any store...they sell food scales just like that...

Cool build. Are the dimples a different color than the rest of the barrel? In the first pic, it is hard to tell but appears that way farther down. If so, how did you do this?

Indeed- many kitchen appliance stores sell these. If you dislike shopping as much as I do, get it online.

The dimples are federal brown and the barrel is a lighter color of coyote tan. To do this I painted the entire barrel coyote and let it cure for a good two weeks. I used the air cure Cerakote, BTW. Then I applied a very thin layer of neutral shoe polish to the smooth, non-dimpled area of the barrel and sprayed the dimples the darker brown. Very quickly after spraying I wiped the smooth parts of the barrel with a tack free cloth soaked in acetone. Wet, but not dripping, of course. I worked on small areas at a time- probably 2" to 3" of barrel or so.

There is probably a better way to do this, but my method was faster than masking and has been holding up well.

[Warg]

A couple of more observations while I'm thinking about this one.

The Millet scope mount holds zero fine, but the mount does not return to zero when removed and reinstalled. I did not intend to remove it often, but I did get some sand and crud under the mount and decided to clean it. I've had much better luck with the more expensive mounts like LaRue, Nighforce, ADM, GG&G, and Bobro. Add a few ounces to your lightweight build for a better quality and hassle free scope mount :)

The lack of an ejection port cover has not been a problem when shooting at the range. It is a problem when packing and upacking in a bag that may accumulate a fair amount of sand and dust like you might encounter in arid climates such as the desert. This is on my to do list.

[hunt_ak]

Thanks for the update. I assume the shoe polish was acting as a 'barrier' between the coyote surface and the brown paint for the dimples. Everything looks incredibly uniform...well done. I might try my hand at something similar someday...

[CGFS]

What was the cost on the barrel dimpling? I'm seriously considering doing this to my AR as it's a bit of a fatty right now.

[devinsdad]

Curious on this as well. The dimpling that ADCO offers is a little to industrial for me, but Pitts dimples look great. Very Knights-like with his pattern. I have a fluted barrel and never thought about doing the flutes in a contrasting color...nice idea.

[Warg]

IIRC, the dimpling was $250.

At the time, Marvin's prices were the following:

Forward of the gas block:
10-12" +25.00
12-14" +50.00
14-16" +75.00
18-20" +100.00

$150 behind the GB

Sandblasting was free and park was $25.

One more update-

I have been using NHMTG mags without issue, but recently discovered that the bolt will not lock back using 20 or 30 round PMAGs. This is somewhat of an issue as some of the handloads I've been using are just a smidge too long for the metal mags. I've tried 35 PMAGs and none of them work. All of these work on my other ARs, but they all sport LMT catches and different lower MFRs. I tried the upper on a couple of the working lowers and the bolt would lock with the PMAGs so I can rule out the bolt carrier/upper.

Oddly, the catch is long enough to engage the mag followers and doesn't bind.

I swapped the bolt catch with another (not sure where it was sourced) and still have the problem. I'll try an LMT catch this week, but if that doesn't work I'll simply stick to metal mags and use standard OAL 204 rounds. I don't think the varmints will care :)

[Warg]

Very Knights-like with his pattern

As it should ;)