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Ultimate Liteweight Precision Grendel Build
#1
My life has been a void for the last month. Sleeplessness. Restlessness. Emptyness. And then it dawned on me. When I finished my Cream S’more, I did not have an AR project in the works for the first time in a very long time. No parts to research, no online price shopping and no anticipation of brown boxes arriving on my doorstep. Do I need another one? Hell no! Do I want another one? Well maybe more than one. Which is where the fix arrives. I have a love / hate relationship with my 18” Stoner / Satern barreled Grendel. I’m currenly back in love as I have it shooting sub MOA with 120 gr Scenar L’s @ 2540 and an SD of 10 with only 30.6 gr of CFE. But given the history of our relationship, I know that love will once again ebb. The plan was always to rebarrel her, but that never got me as excited as it should since I am restricted to an MLGS by her monolithic upper. The solution – start anew. In this day and age where a person can decide they identify with another gender, Gigi can undergo caliber transformation. And so for nothing more than the cost of a rack barrel, muzzle device, Vortex Venom and an ATF stamp from Uncle Sam, she can be reborn as a 10.5” 300 BLK SBR. Very appropriate for the spunky little girl that she is.

My Proof Research 6.5CM barrel has me completely impressed. From the weight to the thermal properties to the fact that I have not been able to get it to shoot anything WORSE than MOA. Once I start playing with jump, I think I’ll have it doing 140 gr RDFs under ½ MOA at 2690 fps with IMR 4451. If that development doesn’t take me where I think it will go, I was actually able to find 10 lbs of H4350 (which is currently about as easy to find as Varget was 2 years ago). And then I saw that Proof now has an 18” RLGS heavy contour Grendel barrel on their website. It’s not at any of their distributors yet, but it’s on their website. And if the 20” tips the scales at the 34 oz like Rainier’s website says, the 18er should be at least no more than 32 oz. Are there lighter barrels out there? For sure. But nothing that would even come close to the combination of its accuracy, long range capability and accuracy after long strings of fire from the guardtower as the zombies crash the prison gate. The closest apple would be a JP 18er with a thermal dissipator at 35 oz – for a LIGHT contour barrel – or a fluted Lilja 319 18er at 34.5 oz.

And so thus was born the idea to build the Ultimate Liteweight Precision Grendel . The goal is not to build the lightest rifle possible. The goal is to build the lightest possible rifle that will be capable of consistently shooting 1000 yards (conditions permitting) and perhaps beyond at my elevation. Functionality and usability will be important. Reliability will be important. At times, aesthetics will be important. I still don’t know if it will be an 18” or 20”. My Proof CM barrel is fast – I’m interested to see if this is common. Or another way to look at it would be as a Precision Rifle capable of carbine duty. Sticks seems to think that a carbine can be 20” so I might hold him too it!

This will be a long term project involving much research, opinion seeking and price shopping. It will be dependent upon funds flow. It will be dependent upon buying parts during the predictable sales. Some parts may be jumped on when good deals are in the works (the first part ordered is a prime example and the receivers will soon be the subject of another thread). My best guess is it will be a 6 to 9 month endeavor for the base rifle. There may be additional time involved to have someone cerakote it digital desert camo. After that, it will be on to scope and bipod (it can share my Atlas and use the Bushnell Elite 3-12x44 on my current 18er to start).

As of today, assuming a 20” Proof barrel is indeed 34 oz, my guess is it will tip the scales at a hair under 6 lbs unloaded (with the 20”) and without optic/bipod; and right around 8 lbs with a 100% usable long range optic (with an mil based xmas tree capable of precise reticle based holdovers at 1000 yards in moderate wind) and bipod. It may perhaps get closer to 7.5 lbs if an ultralight bipod solution out there doesn’t compromise performance and the dollar/krone holds steady. I don’t see a need to set a target for weight or to be under a certain watermark. A pound is simply a unit of measurement and picking a specific weight to be under would target something that is essentially arbitrary and driven by how the underlying unit is defined. It might also lead to compromises that I shouldn’t make. And some lightweight options might get extremely expensive for the weight reduction benefits they offer. And I just don’t want to go with some of the magnesium or lithium alloy options. I’m going to stick with tried and true aluminum, titanium, carbon fiber and (gasp) maybe even steel.

I can look at some of the sub 5lb rifles out there and see exactly where the extra pound comes from – primarily the barrel and the stock, plus a tad extra from the SCS. The barrel is nonnegotiable. The stock may be -that is a discussion for another day. But cheek weld, balance and ability to securely ride a sand bag are important functional requirements.

Posted below is a running list parts purchased, parts that are nonnegotiable and parts I am thinking about and that might be on the top of the list today. This can then be updated as it moves along. Any and all comments and critiques are welcome, but please recognize that we all have differing aesthetic tastes. I’ll initiate threads for certain key parts so that they might not get buried here.

[ATTACH=CONFIG]9797[/ATTACH]


Attached Files
.jpg   Ultimate Lightweight Spreadsheet.jpg (Size: 78.26 KB / Downloads: 193)
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#2
The first key part has been ordered and has shipped earlier than anticipated:

2A Armament Titanium Regulated Bolt Carrier

https://2a-arms.com/collections/bolt-car...lt-carrier

Yeah, it ain’t cheap, but it was actually a pretty good deal with the pre-release sale. Really just a few bucks more than a JP LMOS with bolt. And it weighs in at 5.95 oz with the bolt. In comparison, the JP LMOS carrier (without bolt) is 6.75 oz. The 2A 223 bolt will go into the BLK SBR and I’ll still need a JP Grendel bolt (which is what Proof headspaces to). In addition to the weight, having the gas regulator in the carrier is actually a bigger plus for a lightweight build since it will negate the need for an adjustable gas block – and 0.875” inside diameter adjustable gas blocks can get pretty big. So this opens up the universe of thin profile lightweight handguards that can be used without having to worry about length and clearance. They have a video that shows how the RBC functions on their steel carrier at the bottom of the above link
I’m not terribly concerned about it being too light. It will be mated with a JP SCS with the alternative spring pack. I don’t think dwell time will be an issue with an RLGS and if it is, going to a heavier spring should ease it up. Worst case is I need to put a tungsten weight or 2 into the SCS.
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#3
This is heresy, but if I were going to sink that kind of money into an AR I would handload for, I'd have Dtech build something WSSM based. Rifle from Dtech, brass from Hillbilly and get-a-long little dogie.
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#4
Oooooo I love me a good Stonendge build!!!

I enjoyed following your 22" JP build.

9 months? Pshh... I bet you have it built in 4..

Utilitarian rifles are my favorite, and you are barking up my kind of tree! Pics a long the way, and keep this an even more detailed "blog" than usual. I always look foward to the latest going ons in the interesting world of stonehendge .

Howl
Don't you dare!! I'm going to experience the proof carbon Grendel goodness vicariously through Stonehenge!
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#5
Howl - that is the beauty of our great nation - we all get to spend our $$ how we like!

Kilco - I've got to stretch the timing out. Otherwise I'll just have to start another project when I'm done, and these seem to get more expensive each time! Lol.
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#6
https://brigandarms.com/product-category/handguards/

Lightest handguard I have found. I held one at the fort Myers gun show and it was pretty strong to.
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#7
Bigs28 Wrote:https://brigandarms.com/product-category/handguards/

Lightest handguard I have found. I held one at the fort Myers gun show and it was pretty strong to.

Yummy! I had seen some of those surfing around but kind of wrote them off for lack of a way to mount a bipod. But didn't see the Atlas model with the pic rails on the end. 6.2 oz with barrel nut for the 12.375" with the pic rails....

Did it feel flexy at all? It just LOOKS like it should flex loading a bipod.
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#8
It was pretty sturdy. You could squeeze it and feel some sponge but you had to put some umph in it. They also sell the sections to mount an mlok anywhere so you could get the other models and just put the bipod on the bottom.
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#9
The 2a Armament Balios 2 Lite receiver set was ordered up this morning. Woke to an email saying their "get out to the range sale was ending in 24 hours" and this was a part of the sale
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#10
I'm gonna be following this one closely! Have you used the 2AA RBC before? That looks awesome! But it should ($$$)!Big Grin
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#11
Dave_H Wrote:I'm gonna be following this one closely! Have you used the 2AA RBC before? That looks awesome! But it should ($$$)!Big Grin

Haven't used anything 2AA yet. The RBC actually arrived last night. I pulled it out and it didn't actually feel very light. Put it on the postal scale and it was 8 oz (not the 5.95 they claimed). Looked on their website and saw that their Steel Low Mass RBC is 7.9 oz. Was going to call them first thing this morning and they had an email out at 9:14am saying they had some mispackaged ti carriers and that they would make it good if I had received one of them. I replied that mine weighed 8 oz and they got right back saying another was going out today along with a return label and some swag (including a tshirt in my size). First class response! Primary also shipped the receiver set this morning - one business day for an FFL item rocks too!

Yeah, its $$, but a JP LMOS with bolt is $350 and that's worth every penny in my 22" JP Grendel build, so I figured I'm ahead of the game 2 ounces and the built in regulator with the intro price Big Grin. The bolt coating doesn't compare with JP's chromium nitride though - nothing cleans up like a JP bolt!
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#12
Look at the Odin Works 02 lite handguards. Have one on my JP (look through my thread for pics). They are super sturdy, and very light in weight.
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#13
nismosao Wrote:Look at the Odin Works 02 lite handguards. Have one on my JP (look through my thread for pics). They are super sturdy, and very light in weight.

I had checked them out, but the 12" 2A handguard that would match up with the upper receiver is actually 2 oz lighter than the 12" Odin - and that includes a Ti barrel nut and I don't think the Odin weights include the barrel nut.
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#14
The Odin 12.5" weighs with nut 8.1 in key mode, 8.3 for m-lok including the nut.
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#15
Yah the key mod version of the 02 lite weighs the exact same as the 2A with the nut included, but is 12.5 inches long compared to 11.87 for 2A.

And you get a free accessory rail.
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#16
Yeah - I had been looking at the normal Odin handguard and it looks like the O2 and 2A are about the same. Got my real 2A Ti RBC in last night and a business card holder was part of the swag:

[ATTACH=CONFIG]9853[/ATTACH]

They must know I'm in the market for a rail - lol. I really dig the aesthetics and slimness and the 2A is definitely on the top of the list if I go the aluminum route since it should match up perfectly with the 2A upper receiver.

The weight on the Ti RBC is as advertised:

[ATTACH=CONFIG]9854[/ATTACH]

3.8 oz for the carrier,alone without bolt and pins:

[ATTACH=CONFIG]9855[/ATTACH]


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#17
This is how the 2A section covers me S'more barrel which is the same contour as the Proof Grendel barrel

[ATTACH=CONFIG]9857[/ATTACH]


Attached Files
.jpeg   image.jpeg (Size: 82.9 KB / Downloads: 79)
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#18
I guess there's a reason why we exercise patience with things. Looks like Smoke Composites will now do a cheek riser!

[ATTACH=CONFIG]9865[/ATTACH]

Switching the stock and hand guard to smoke puts it at around 5.4 lbs unadorned without the cheek riser (they don't list a weight).


.pdf   Ultimate Lightweight Spreadsheet.pdf (Size: 21.96 KB / Downloads: 52)

To put it in perspective, if it were to have a 16" Faxon Gunner barrel, it would be estimated to tip the scale at 4.8 lbs


Attached Files
.jpg   Smoke Cheek riser.jpg (Size: 62.98 KB / Downloads: 174)
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#19
Holy crap man that thing is looking sexy!!
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#20
Kilco Wrote:Holy crap man that thing is looking sexy!!

Lol - I just pulled that from their website. The only thing I have in hand is the Ti RBC. Receiver set is at my FFL but the first snow of the season delayed my getting it. Hopefully Thursday. I put the stock and handguard and all of the accoutrements into a shopping cart at Smoke and had a spontaneous coughing fit moments after I clicked "View Cart"

Really hoping to get a confirmation of the Proof barrel weight so I can do a semi mockup to get an idea of balance.
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