Home Forums Hunting & Shooting AR and Tactical Rifles 22", 8 twist, .243 LBC build.

I finally got a chance to shoot the latests AR I built, I built this one for myself. This will be one of my primary RockChuck AR's. Back East I believe they call them Groundhogs, out west it's Rockchucks because they are almost always found in rocky terrain. Anyway I was more than pleased with today's results.

Since this was the first outing with this rifle but I own and have shot many Black Hole Barrels in various chamberings, .243 LBC, .264 LBC, 6x45, 6.5 PCC, 6x6.8 SPC etc. I did my standard break in. 3 shots clean with Butches, 5 shots clean with Butches, 5 shots clean with Butches, 10 shots clean with Butches and then go for it. All the shooting was done from the prone with a bipod and a rear bag at 110 yards.

Here are a couple groups shot today the group on the left was 5 shots with 105gr Hornady BTHP match and CFE223 powder with Lapua cases(Yes, I choked the last round!) The group on the right was 3 shots with the 95gr Berger VLD's and H4895 in neck turned Hornady cases. Both lit with a CCI BR4.





I have noticed that my AR's that I use the heavy billet Maga Arms upper recievers. Side charger type or standard heavy upper receiver have always shot tight.

Today's set up, I didn't have time for a formal range session off the bench and I couldn't stand the wait. So next go round I'll get velocities. Right now I just wanted a zero.





Rifle Specs:

22" Black Hole Weaponry barrel, stainless, 3P (Polygonal).
Chambered in .243 LBC, simply the Grendel necked down to 6mm
Rifle length gas
Fortis "RED" brake/Compensator
Geissele Super gas block
Nitride gas tube
Lancer 16.25 carbon fiber handguard
Mega Arms side charger upper
NIB bolt carrier group with custom side charger machined and installed locally
Grizz Precision Billet lower receiver
Anderson lower parts kit
CMC 2/2 flat two stage trigger
Yankee Hill extended take down pins
Odin Works extended magazine release
MagPul PRS stock with .308 spring and buffer
MagPul Key Mod bipod adaptor
Spikes "Spider" grip
Viking Tactical Key Mod single point/clip sling attachment
Noveske 60 degree selector/safety
AADMOUNT 30mm with bubble level and 30 MOA built in
Leupold LRT, M1, 6.5-20x50 Mil-Dot reticle

Nice,what is the weight ?

You had to ask! So much for the Lancer handguard cutting weight on a build like this.

Almost right at 13lbs with a empty mag. Recoil is minimal and impacts are easy to watch, even on 20x.

Well its still nice
Setting up for a long stay in one place all that weight would make recoil very light .
Congrats on your build

How do you like the Lancer handguard?

It's quality built and stout. I have high end aluminum key mod handguards that flex more when you "Load" the bipod.

Sweet! I have an upper/lower with a Geiselle NM match trigger, PRS stock and the same Lancer handguard sitting in my study, and was just researching the best 6mm cartridge for the AR15 platform. I had planned another 223 but have 4 already, and not a fan of the AR10 platform, just too big to me.

Seriously thinking about building a 243LBC VERY similar to yours! Was thinking 24" but seeing your pics has me questioning that.

Really appreciate the list of components, etc. Would love to hear any tips, advice, thoughts you might have in hindsight, etc.

This rifle was built from hindsight. I first built one in a 6x6.8 SPC, it was fine for bullets up to 90gr or so but the 6.8 Cartridge is longer than the Grendel cartridge and I wanted to shoot the heavies 95gr VLD's and heavier Hornadys. So after 700 or so rounds and two mule deer with the 6.8 SPC.

I decided to build the .243 LBC which has the shorter parents case and can handle the cartridge over all length with the heavies loaded at magazine length. Which is 2.300 with my current ASC magazines(6.8 SPC mags).

The bullet I built the rifle for is the 95gr Berger VLD Hunting bullet. If I can get close to 3000 fps with them I will be extremely happy.

6x6.8 SPC



The 90gr Accubond(6x6.8 SPC)70 yards on a Mule deer.



The 95gr Hornady SST (6x6.8 SPC) 287 yards on a Mule deer.

Look's good.

What velocity were you running the 6.8 SPC with those two bullets?
Reason I ask is I have a 6.8 AR Performance barreled upper(16 inch) that should be here in a week or so but will be shooting the 120 SST Hornady factory load.
Think the 120 SST will work all right on similiar sized deer for say 50 yards to 200 yards ?

Around 2980, I imagine I could have pushed harder but I was getting 1/2 MOA.

Wow that is smoking !
What barrel length?

22" barrel

Here is the pic of the Magnetto speed after a 3 shot string, from a friends 24" barrel chambered in .243 LBC. Shooting the 95gr Berger VLD's over 8208 powder. The load shoots under 1/2 MOA .

Gave the 105gr Hornady A-Max's a go today. Conditions were less than ideal. Switching, gusty winds up to 10mph or so with a drizzle of rain here and there, 50 degrees.

All and all I was pleased with my initial results with the A-Max's. Definitely MOA of RockChuck. All groups were 5 shots at 100 yards. I fired the first group with a super clean cold bore using the 105 Hornadys. Then I shot the 105gr A-Max groups.

How many BHW barrels have you dealt with in .243 LBC? I've been real torn between a 6.5 Grendel and either a 6mmAR/.243LBC or 6mm V Fat Rat. I want a 20-22" barrel with the most payoff. I had been leaning towards the Grendel because I'm shooting a 6.5 Creed and could run a common bullet but I'm not married to the idea. Every time I see a 6mm version I start to sway.

A Black Hole barrel in a 22" , 8 twist. Chambered in .264 LBC would be a exellent choice. I own three and have shot and built many others. They have their 8 twist, 6.5 barrels dialed in.

The .264 LBC has been their most consistent performer for me accuracy wise. With the 123gr A-Max and SST. They even shoot the 130gr Accubond well.

This is a 7 shot group at 100 yards with a Black Hole 18" SPR barrel. Chambered in .264 LBC with a 8 twist.



Same barrel at 100 yards with factory Hornady 123gr A-Max and 123gr SST 6.5 Grendel ammunition.

These were shot with a cold clean bore, the clean bore shot was always predictable.



Some .264 LBC's

Thanks for the feedback. Do you know if BHW will do rifle-plus length gas path or is rifle length gas as long as they go? How fast are you able to push the 123gn bullets? I have lots of 123gn SMK but only a few hundred 123gn A-MAX left. I would like to hit 2500fps minimum. My goal is to equal or beat a large frame .308 for DMM and have a companion gasser to my Creedmoor bolt gun for partner matches where we aren't required to shoot .308 rifles.

I know there are some variable but is #13 about what your builds end up weighing?

A 22" barrel in a .264 LBC will give you 2500 plus with the 123gr A-Max's easy. Longer barreled AR's aren't light. You can keep them around 11lbs if you dump the PRS stock and go with a ACS-L.

11# works just fine. That's where my current rig is sitting. I'll use a Luth AR MBA3 in place of the PRS since my lower has a carbine extension. I had also looked at Proof barrels for the Grendel but haven't decided. Not sure if the juice is worth the squeeze on that one.

Took the .243 LBC out to 300 yards today to get my real world dope for drop from my 100 yard zero. I had a series of dots strung vertically at 300 yards. Slight right to left breeze and a slight rain/drizzle. With my 100 yard zero, I held the top dot and fired three. Drove out and measured the group and the drop. The 3 shot group (Bottom target in the photo) printed .925 and was exactly 12" low at 300 yards from my 100 yard zero. I then drove back to the bench dialed 4 MOA up on my turret and fired 5 at 300 yards for a group (Top target in the photo) the 5 shot group printed 1.388

What contour barrel did you use on this build and your longer .264 LBC?

The current 22" .243 LBC has a custom contour. It's between a light contour and a standard. It's a contour that Griz Precision uses.

My long .264 LBC is a 26" full bull contour. As far as I know only two 26" full Bulls were ever made by them for a AR. My guy that was great to work with at Black Hole has since left them and he's the one that did a barrel for me and himself.

Here's three of my 8 twist Black Hole .264 LBC barrels. All are 8 twist and rifle length gas, all are threaded 5/8-24.

Top 26" full bull
Middle 18" SPR
Bottom 16" custom "Hammer Flare" contour

Did some load development today with the 95gr Berger VLD Hunting bullet and some CF223. The load on the left looks like a solid load.

2999 FPS
SD. 5

.243 LBC
22"
8 twist Black Hole Barrel

Don't forget, get away from the chrono once you are happy with the speed area you are at. Results on paper trump ES and SD on the chrono every last time....

IE don't chase magic numbers, just shoot for groups.

I have three solid half MOA loads.

95gr SST's @ 2887
105gr A-Max @ 2801
95gr Berger Hunting VLD @ 2999

I really like the performance of the 6mm 95gr SST on deer but I have not taken any deer with the 95gr Berger VLD or the 105 A-Max. I have yet to work up a load with the 90gr Accubond in this rifle (.243 LBC) but I have shot a Mule deer with the 90gr Accubond in the 6x6.8 SPC chambering and it performed well.

The thing I find annoying with most wildcat AR's I have built is the curse of the first round slightly out. I lock the bolt to the rear, seat the magazine and and release the bolt. I have tried dropping a round in the chamber. Then releasing the bolt, then inserting the mag. I've tried riding the bolt with the charging handle for the first round. More often than not it puts that first round slightly out. Drives me crazy!

Got nothing to add except nice rifles and shootin smack!

Good to know you are happy, thats some good groups. I"ve never seen the 1st round issue, but then I don't have many ARs that are not 223.

RE the chrono, point was for load tweaking, ES/SD mean less in the long run than what paper tells you at your max distance. Disregarding things that start at 500-600 or so and head furhter out... then ES is an issue, but it will also show on paper targets as vertical spread.

I've yet to end up shooting the most promising load according to my chrono EVER....

Interesting thread, I never have worked with the Grendel, or any of its variants. Might be a fun build, after I get a couple of 5.56's finished

Bumping an old post for updates. Smack, now that you've had this 243 LBC for a while, do you have any more feedback or advice?

I'm thinking of putting one of these together now. I'll be starting from scratch on dies, components, bolt, barrel, etc, but it looks like I can use 6 PPC dies, and I'll probably go with a BHW 1:8 barrel. I'm thinking 20-24" but haven't pulled the trigger yet.

20"
1-9 twist
CFE223 powder was great
.243 LBC dies can be purchased from CH4D tool & Die. Great people!
Use ASC 6.8 SPC mags

Thanks for the feedback! Tried to contact you on the HuntWA board but no success - do you still sell BHW barrels? If so I'd like to find out some info from you on buying one. If not, other suggestions are welcome too.

Any rough estimate of velocity with a 20" compared to your 22" loads I quoted above? I'm leaning towards that 95gr VLD based on what I've read, hoping for close to 3000 fps. I do like the idea of a slightly shorter 20", and may go with a standard or lighter profile instead of a heavy barrel. Open to suggestions there. I'll use an ACS-L stock and hope to keep it at 10-11 lb max.

Just curious on your 1:9 twist recommendation - does that give up anything compared to 1:8 with 105/107gr bullets?

Good info on the dies, powder, and mags. Already have that powder and several of those mags for 6.8 based wildcats, so that works out well. Thanks again.

Love it when a plan comes together; even better when you get lucky right from the start. That 32.4gr load shows promise in my rifle too... Thanks for sharing it, Smack!



This is only the second group ever with this rifle, 5 shots at 100, prone with bipod and a rear bag. Those are 1" squares on the target, group size is right at .500".

I got my 243 LBC barrel from Black Hole recently (they were actually pretty fast on this one, only 4-5 weeks) and assembled it in a thermofit BCM upper. I went with a 1:8 twist, standard profile, very similar to Smack's barrel above but 24" length. My goal was 10 lb with scope, sling, and an empty mag; this one ended up at 9 lb 14 oz.

Do I need to call CH4D for dies because I didn't see them listed on their sight. What bushing are you using?
I'm planing on getting a 22" barrel, 1-8tw, Aero upper and lower.

I emailed CH4D and they did have a couple sets left, but I ended up just using some 6mm PPC dies instead, no issues with that. I'm not using bushing dies.

Y'all are killing me with these. I want one but wish they offered a +2" gas system.

From shooting mine, with a properly adjusted gas block - I don't see any need for a +2" gas system. Rifle length is fine, just tune the gas correctly.

IMO people put way too much emphasis on AR gas system length, and not nearly enough on tuning the gas.

I agree that tuning is important but there is a reason you don't have a carbine or pistol gas length gas system on that long barrel of yours.

Sure there's a reason, but it's a lot less important than many online seem to think. Gas metering (either port size or gas block adjustment) plays a much bigger role in bolt timing than port location.

As I said, mine runs fine with rifle length gas when properly adjusted. Why do you think you need +2"?

I'm sure it does run just fine. Why do they offer mid and rifle on a 20" .243 LBC? Because people want it and either will work. Why do the stop offering mid length on a .243 LBC at 22"? Because it's not optimal. Several guys I shoot with who shoot the 6mm Fat Rat and V Fat Rat use it with longer barrels (24 to 27" and one 27" with a suppressor) and +2 gas with great results. You even see plus gas on .223 Match rifles. I'm not saying it is a requirement for a .243 LBC anymore than it is a requirement to use rifle length vice mid on an 18" .223 Wylde but I'm saying it might not be optimal to use the shorter gas path. Where is the gas port on an M1 Garand? Was it a terrible plan?

Yondering,

Exellent results. The .243 LBC chambering just wants to SHOOT! I have a bunch of load data for it.

Mine shot the 105gr A-Max really well!

Here's just a few 300 yard groups. Solid 1/2 MOA rifle!