New 6mm Advanced Rifle Cartridge

[skyrep]

The 6mm ARC cartridge IS IN Quick Load latest update. However, you need to use the "qloadfw.vol" file to bring it up. I compared it to my data that i've collected and it's within 10-15 FPS. I change the case length to what I am loading to which is 1.480.

 

[SMTGWKD]

Quick post to provide data points. I own 16" and 12" Grendels and really like them, but haven't liked velocity for their accuracy nodes/brass limitations when shooting suppressed (about 2380 with 123s from the 16"). It drops the efficiency of the bullet quite a bit as I can't take advantage of the highest BC tier at those velocities.

The setup below weighs 6.7 lbs without the scope and averaged 2618 fps over 5 shots (Labradar) from the 18" barrel with 105 Hornady Black.

First group was 6 shots after break in and cleaning. The cold bore shot was 1.5" or so low.

Second group is 5 shots immediately after the first group.

Third group was fired more quickly immediately after the first two groups.

I'm really interested to understand the vertical stringing of the third group as Carbon barrels have been great at mitigating that in the past. Certainly could be me, but I don't think so

So far really impressed by the cartridge - a 105 with .530 BC traveling at 2618 (over mach 2.25) literally demolishes a 123 with .493 traveling at 2380 (mach 2ish).

 

[ormandj]

I have two barrels from Craddock incoming this weekend, a 18” and 10.5” Bartlein. I don’t know if I’ll be able to get out to shoot them until the following weekend, but will have them together and ready to go shortly after delivery. I’ve got a LabRadar and will chronograph some factory ammunition (108 ELD-M). Any requests beyond this?

 

[skyrep]

I have two barrels from Craddock incoming this weekend, a 18” and 10.5” Bartlein. I don’t know if I’ll be able to get out to shoot them until the following weekend, but will have them together and ready to go shortly after delivery. I’ve got a LabRadar and will chronograph some factory ammunition (108 ELD-M). Any requests beyond this?

will be interested in how the 10.5" barrel does. I've got an 12.5 X-Caliber being spun up.

 

[Bantam1]

What magazines are you guys running?

 

[ormandj]

will be interested in how the 10.5" barrel does. I've got an 12.5 X-Caliber being spun up.

Won't spoil the surprise too much, but let's just say it's already been tested and the results weren't negative.

What magazines are you guys running?

CPD Duramags (10/20/26 rd) on my end.

 

[SBRSarge]

You guys are making me jealous. I have an 18” Odin on back order and they can’t even give a guesstimate of delivery. They’re awaiting the material to make them.

I might have to look around a bit. If I find one, I’ll have to try and cancel the Odin order, but the price was fair and included the gas system and BCG for 500 shipped.

 

[Bantam1]

I'm still waiting on a JP BCG and a barrel. I'm still debating on what handguard I want to run.

 

[ormandj]

You guys are making me jealous. I have an 18” Odin on back order and they can’t even give a guesstimate of delivery. They’re awaiting the material to make them.

I might have to look around a bit. If I find one, I’ll have to try and cancel the Odin order, but the price was fair and included the gas system and BCG for 500 shipped.

I wouldn't cancel if you like Odin barrels. My order was in process pre-announcement and it's just now on the way. The barrel manufacturers are really busy right now with government and civilian sales, so it's just a waiting game. You might spot one for sale, but it's probably going to be either expensive (Proof) or rack-grade. Not sure on Odin barrels, but I assume they are better than this?

 

[SBRSarge]

I wouldn't cancel if you like Odin barrels. My order was in process pre-announcement and it's just now on the way. The barrel manufacturers are really busy right now with government and civilian sales, so it's just a waiting game. You might spot one for sale, but it's probably going to be either expensive (Proof) or rack-grade. Not sure on Odin barrels, but I assume they are better than this?

Yeah, I have an Odin on an SBR and like it. And the folks who have gotten the Odin 6ARC barrels have reported great results with them. Wish I could afford a Proof but I need to buy a scope for the build also!

So, I guess the wait gives me a chance to save more for a scope... Hmmm, time to look at another Nightforce...

 

[Yondering]

What magazines are you guys running?

I've been using ASC and ELander for a few years for everything Grendel-based (and the same ASC mags before that for anything SPC-based). Both are good; my ELanders seem to feed a little better, but require a shorter OAL so I use them for my 105gr BTHP load which fits nicely.

The stainless ASC mags can run comfortably at 2.300" for the really long bullets, and FWIW my 6.8 SPC ASC mags seem to function just as well as the Grendel mags when used with Grendel-based cartridges. I can't see much difference between the SPC and Grendel versions.

 

[tomcatfan]

I got my ammo in from Midwest and I was able to try Hornady Black ammo. My set up doesn’t like it nearly as much as the 108 eld match ammo. My 21" Odin works barrel averaged 2682 fps and 1.046" groups at 100 yds Shooting 3, 5 shot groups. In comparison the 108 eld match ammo averaged 2715 fps and 0.692" groups at 100 yds. My best group with Hornady black was 0.745" and it was 0.385" with the 108 eld ammo.

I didn’t measure my OAL but I had to use my forward assist to chamber the black ammo a couple times, I didnt have the same issue with the 108 eld ammo.

 

[SWFShooter]

I got my ammo in from Midwest and I was able to try Hornady Black ammo. My set up doesn’t like it nearly as much as the 108 eld match ammo. My 21" Odin works barrel averaged 2682 fps and 1.046" groups at 100 yds Shooting 3, 5 shot groups. In comparison the 108 eld match ammo averaged 2715 fps and 0.692" groups at 100 yds. My best group with Hornady black was 0.745" and it was 0.385" with the 108 eld ammo.

I didn’t measure my OAL but I had to use my forward assist to chamber the black ammo a couple times, I didnt have the same issue with the 108 eld ammo.

That is probably because the bullet is jamming into the lands with the 105s. Hornady loaded them at 2.250", when they need to be about 2.205". If you have a seater die for 6mm ARC, just seat them a bit deeper so they aren't a hard jam.

 

[Henryrifle]

Spent some time at the range today testing two changes. Wanted to verify that changing from CCI BR4 primers that I want to conserve for competition to CCI 400s was as much of a non-event as initial testing indicated.

That remains true even in temperature that is 7 degrees cooler than the last test. I even reduced the charge weight by 1/10 of a grain as the CCI 400s create slightly more MV than do the BR4s. SDs with the 400s are also better even when comparing the worst of the SDs with the BR4s. Not what I would have expected.

The second part of the test was seating depth. I started at magazine length and shot seven 5-shot groups increasing (making OAL shorter) seating depth by .003" in each subsequent test.

All of this was shot at 100 yards from prone using Hornady brass, Hornady 108 ELD-M projectiles, CCI 400 primers, Harris bipod, Bigfoot rear rest, Nightforce 5.5-22 and TBAC Ultra 9 suppressor.

Results:
COAL—MV—SD—MOA
2.260—2584—6.3—.86
2.257—2581—4.8—.76
2.254—2584—1.4—.37
2.251—2586—4.5—.86
2.248—2581—5.5—1.01
2.245—2585—13.4—.5
2.242—2586—12.7—.44

All of the above were shot with 28.2 grains CFE223. If you graph the results there is a definitive repeating wave-like pattern of increasing and decreasing accuracy. Unfortunately, better accuracy correlates with increased SD for the shorter two nodes (2.245 & 2.242). Will retest the three best groups to see if any repeat.

Attached are the targets from today but ignore the hand written date and temperature information on top of the target. It really was shot today, 9/26 and the temperature was 73.5 degrees with 80.3% humidity and a density altitude of 2322 feet.

Bonus info: I finally did receive some Hornady 108 ELD-M factory ammo. The speed is impressive out of my 21.75” barrel at 2721 FPS with an SD of 4.6 but the accuracy was disappointing at 1.7 MOA and 1.3 MOA. I shot the second group as carefully as I could. I may have been a little less precise on the first group.

Last note. That .86 I shot at a COAL of 2.260 is at the high end of the normal spectrum. The rifle and that load averages .68 MOA but it is what it is.

Henryrifle

 

[jbailey]

wow, what a stark difference between your reloads and factory. Nice tight groups vs disasters. thanks for posting.

 

[jbailey]

Also Craddock Precision is shipping 6ARCs. I received my Rock Creek barrel from them. I placed order back 3 months or so (not sure?)... I just need to find some 6ARC brass now.

 

[NH4X]

Spent some time at the range today testing two changes. Wanted to verify that changing from CCI BR4 primers that I want to conserve for competition to CCI 400s was as much of a non-event as initial testing indicated.

That remains true even in temperature that is 7 degrees cooler than the last test. I even reduced the charge weight by 1/10 of a grain as the CCI 400s create slightly more MV than do the BR4s. SDs with the 400s are also better even when comparing the worst of the SDs with the BR4s. Not what I would have expected.

The second part of the test was seating depth. I started at magazine length and shot seven 5-shot groups increasing (making OAL shorter) seating depth by .003" in each subsequent test.

All of this was shot at 100 yards from prone using Hornady brass, Hornady 108 ELD-M projectiles, CCI 400 primers, Harris bipod, Bigfoot rear rest, Nightforce 5.5-22 and TBAC Ultra 9 suppressor.

Results:
COAL—MV—SD—MOA
2.260—2584—6.3—.86
2.257—2581—4.8—.76
2.254—2584—1.4—.37
2.251—2586—4.5—.86
2.248—2581—5.5—1.01
2.245—2585—13.4—.5
2.242—2586—12.7—.44

All of the above were shot with 28.2 grains CFE223. If you graph the results there is a definitive repeating wave-like pattern of increasing and decreasing accuracy. Unfortunately, better accuracy correlates with increased SD for the shorter two nodes (2.245 & 2.242). Will retest the three best groups to see if any repeat.

Attached are the targets from today but ignore the hand written date and temperature information on top of the target. It really was shot today, 9/26 and the temperature was 73.5 degrees with 80.3% humidity and a density altitude of 2322 feet.

Bonus info: I finally did receive some Hornady 108 ELD-M factory ammo. The speed is impressive out of my 21.75” barrel at 2721 FPS with an SD of 4.6 but the accuracy was disappointing at 1.7 MOA and 1.3 MOA. I shot the second group as carefully as I could. I may have been a little less precise on the first group.

Last note. That .86 I shot at a COAL of 2.260 is at the high end of the normal spectrum. The rifle and that load averages .68 MOA but it is what it is.

Henryrifle
View attachment 7433241
View attachment 7433242

If you still have some 108 factory loads, would / could you post a picture of a 108 laying beside it? I'd like to see how much,if any, of the bearing surface of bullet is below the neck/ shoulder junction,if any.

Thanks for letting us know how this testing is going ........it very interesting

 

[tomcatfan]

Bonus info: I finally did receive some Hornady 108 ELD-M factory ammo. The speed is impressive out of my 21.75” barrel at 2721 FPS with an SD of 4.6 but the accuracy was disappointing at 1.7 MOA and 1.3 MOA. I shot the second group as carefully as I could. I may have been a little less precise on the first group.

So your velocity with factory ammo is almost the same as mine using a 21" barrel. It’s sad to see there isn’t a powder available that gives similar performance to the factory stuff without pushing pressures.

 

[Henryrifle]

Attached photo is one of my reloads that measures 2.2540" OAL. At most it is .006" shorter than a factory loaded round. That's a lot of projectile below the neck!

@tomcatfan: the CFE223 load that I am working with at 28.2 to 28.3 grains is .9 grain lower than Hornady's published max. I think there is a good amount more velocity to be gained and I haven't tried LEVERevolution yet. There is nothing special about the load I am developing other than it meets my goal of staying supersonic [really close at 1260 fps] out to 1000 yards and shoots close to .5 MOA.

 

[tomcatfan]

Fair enough, why push the pressure if you can check all of the boxes. Thanks for the heads up.

 

[Henryrifle]

I got a hall pass and dashed out to the range to retest the seating depths that looked so promising from above. Some days I am just off and I knew right away today was one of those days. No excuses though. I know I pulled one shot in the 5th group but once I retrieved the target I realized that it didn't kill the group size. It was the highest shot. I can't explain target 6 but I know it was poor gun handling that spread it out.

One interesting observation. It was 4 degrees warmer today than the last outing and speeds were up about 16 FPS. I will have to look back at other data and I don't imagine that it is linear but does anyone have an estimated MV increase per degree of temperature for CFE223? These two days would indicate 4 FPS per degree but that seems high??

My conclusion from this testing is that this gun with this load and me as the shooter create average groups of .75 MOA and I know I can put together a box of 50 or so and have fun shooting steel out to 1000 yards. That also gives me freedom to try other powders and charge weights.

Lastly, CFE223 seems REALLY dirty. I know ARs get dirty fast suppressed but CFE223 seems especially dirty.

 

[Ledzep]

1.3-1.7 fps per degree with CFE 223.

MV avg. settles in after about 10-15 rounds in a string. By that I mean you get a large enough sample size to get past most of the noise. MV will also slowly walk up as the barrel fouls. I've seen 7-30fps per 50 rounds depending on caliber. Most are 7-15.

 

[NH4X]

@Henryrifle ......thanks for the picture of bullet beside loaded round. Yes cfe 223 is on the dirty side , its all i use in 223 and 22 nosler.because it meters so well and the claimed copper eliminator......which seems to be some what true. Will be interesting to see the difference between it and leverlution in your tests.

 

[Ledzep]

I've been seeing a lot of soot with CFE223 and LVR. Almost no copper fouling in any of my 3 ARCs, but lots of soft carbon. Just got my ultra-5 out of Jail and the AR now ejects almost entirely black cases. Seems worse than my .223 uppers.

 

[260284]

I used to shoot my Grendel suppressed and when I sold it, I didn't miss the dirty brass. All I used was CFE and XBR. Velocities were slower with XBR, but it was temp stable and that made the loss in velocity worth it. I am waiting to see how the 6 ARC shakes out. May have to build a shorty upper for a suppressed truck gun after I get my Dominus in.

 

[LRBuck]

1.3-1.7 fps per degree with CFE 223.

MV avg. settles in after about 10-15 rounds in a string. By that I mean you get a large enough sample size to get past most of the noise. MV will also slowly walk up as the barrel fouls. I've seen 7-30fps per 50 rounds depending on caliber. Most are 7-15.

Thank you Henryrifle and Ledzep for all the info. I am waiting on a 22” Craddock Precision Rock Creek barrel. (Hopefully it will arrive this week) Having 223 and CCI #400 primers available, I plan to work up similar loads though I was planning to work with Varget for my hunting rounds. This is very very helpful to a new reloader like me.
The temp instability of CFE 223 is more than I had read somewhere but I certainly defer to Ledzep’s experience With it.

 

[Henryrifle]

Good luck with you new barrel, LRBuck. It can be very satisfying to assemble your own rifle, build, test and refine your own ammo and achieve your accuracy and purpose objectives. Looking forward to reading about your results.

Anyone testing with AR-Comp and 105 to 108 grain projectiles in an AR? If so, what kind of velocity are you getting?

Henryrifle

 

[ormandj]

Good luck with you new barrel, LRBuck. It can be very satisfying to assemble your own rifle, build, test and refine your own ammo and achieve your accuracy and purpose objectives. Looking forward to reading about your results.

Anyone testing with AR-Comp and 105 to 108 grain projectiles in an AR? If so, what kind of velocity are you getting?

Henryrifle

I will be. Barrels are here just need to go shoot some factory to harvest some brass.

 

[ormandj]

10.5" and 18" Bartlein barrels from Craddock (Dead Air KeyMo brakes - I shoot 100% suppressed so these are just blast baffles for the suppressors). .750 gas block journal size for diameter reference.

10.5" weighs 534 g / 1 lb 2.83 oz, and the 18" weighs 935 g / 2 lb 0.98 oz (without brakes). KeyMo brakes weigh 112 g / 3.9 oz each.

 

[Henryrifle]

I like your style! Can't wait to read about performance and especially at the AR Comp! I guess I have to go clean mine now.

Good luck with them,
Henryrifle

 

[ormandj]

Check out the gas port - no burr here:

 

[Jmccracken1214]

Anyone know if theres any truth to what White Oak has posted about this caliber.... saying something along the lines of the bolt being too thin, with higher pressures, causing it not to be reliable?

I dont see how it differs much from the 6.5G.... maybe slightly higher pressures with the 6?

Wanting to build an AR, but decided against 224V due to poor primer pocket life.. Ive had a dozen grendels and like them, but want more speed but wanting something different than the 223.

 

[ormandj]

Anyone know if theres any truth to what White Oak has posted about this caliber.... saying something along the lines of the bolt being too thin, with higher pressures, causing it not to be reliable?

I dont see how it differs much from the 6.5G.... maybe slightly higher pressures with the 6?

Wanting to build an AR, but decided against 224V due to poor primer pocket life.. Ive had a dozen grendels and like them, but want more speed but wanting something different than the 223.

It's no different than the Grendel, same bolt face, same pressure (52kpsi). While I can't directly knock WOA for their quality, as I've read positive reports, I think their statement is out there and silly. They're basically stating the obvious, you can't load it to 60kpsi like you would in a bolt gun. Not everybody is looking for that - 52kpsi gets me the velocity I need out of my barrels to shoot at the distances I want with the right mix of recoil/windage/energy at the distances I care about (out to 1000). There is no single 'best' cartridge, they are all tradeoffs. I really like the tradeoffs on the 6mm ARC for my purposes (range to 1000 and hunting at reasonable distances). If I want to go shoot ELR I bring out something overbore and deal with the recoil and barrel life issues (and component costs/ammo weight/rifle weight/etc).

 

[Henryrifle]

With no intent to be argumentative, I read the WOA statement as saying that their experience with cartridges like the 6mm ARC when pushed* put more wear and tear on the bolt and bolt extension than they are comfortable with—for competition—their primary focus.

What makes the 6mm ARC potentially different it that it is a SAAMI spec’d cartridge with a published maximum chamber pressure of 52K PSI.

*As hand loaders we can choose to remain inside a published design envelope or exceed it. If some part of the military did select this cartridge then one could reasonably expect that considerable testing has been done and that critical parts did not fail or significantly degrade prematurely.

I claim no knowledge of those tests or what those criteria may have been but, it isn’t reasonable to repeatedly push any mechanical device beyond its design limitation with no expectation of accelerated wear eventually leading to unreliable operation or failure.

On a personal note, I think it is awesome to have an AR15 platformed rifle that is capable of impacting steel out to 1000 yards and beyond with factory ammo. Maybe the 6.5 Grendel and other SAAMI cartridges can do that too. I have a little over 400 rounds through my 6mm ARC. I believe that I have kept the pressure within the specs and, so far, there is no apparent wear on my bolt’s lugs.

This is more my reasoning for why I own one of these rifles and hopefully not delivered or interpreted as a defensive response to a negative-sounding stance by WOA.

Henryrifle

P.S. I have had nothing but fantastic service and assistance/advice from WOA. In fact, I purchased my Wilson barrel from them that is currently in use on my 6mm ARC!

 

[ormandj]

With no intent to be argumentative, I read the WOA statement as saying that their experience with cartridges like the 6mm ARC when pushed* put more wear and tear on the bolt and bolt extension than they are comfortable with—for competition—their primary focus.

What makes the 6mm ARC potentially different it that it is a SAAMI spec’d cartridge with a published maximum chamber pressure of 52K PSI.

*As hand loaders we can choose to remain inside a published design envelope or exceed it. If some part of the military did select this cartridge then one could reasonably expect that considerable testing has been done and that critical parts did not fail or significantly degrade prematurely.

I claim no knowledge of those tests or what those criteria may have been but, it isn’t reasonable to repeatedly push any mechanical device beyond its design limitation with no expectation of accelerated wear eventually leading to unreliable operation or failure.

On a personal note, I think it is awesome to have an AR15 platformed rifle that is capable of impacting steel out to 1000 yards and beyond with factory ammo. Maybe the 6.5 Grendel and other SAAMI cartridges can do that too. I have a little over 400 rounds through my 6mm ARC. I believe that I have kept the pressure within the specs and, so far, there is no apparent wear on my bolt’s lugs.

This is more my reasoning for why I own one of these rifles and hopefully not delivered or interpreted as a defensive response to a negative-sounding stance by WOA.

Henryrifle

P.S. I have had nothing but fantastic service and assistance/advice from WOA. In fact, I purchased my Wilson barrel from them that is currently in use on my 6mm ARC!

Not taken as an argumentative stance at all. I'm just confounded by their statement (preceding information omitted as not relevant to my discussion):

We have built many rifles in various wildcat cartridges on the .440 head size case, as well as the .264 LBC. What we found is that they just do not give the reliability and longevity that we as target shooters need at the pressures that we typically shoot. In the crucible of competitive highpower shooting, where we tend to tip the powder can to the limit of what the case will hold, they did just not hold up. Other gunsmiths built them and had success with them, but lug set-back and breakage was at a level that I was personally uncomfortable with. At that time I made the decision to not chamber for the .440 head size cartridges. In addition, I feel there are other cartridges that are better for the specific demands of the across the course match rifle shooter.

Hornady confirmed by my feelings by limiting the new cartridge to 52,000 PSI max pressure. At that pressure bolts and barrel extensions should last a long time. Start tipping the powder can and all bets are off. If you are one to add powder until primers fall out then back off slightly, don’t expect to keep all the lugs on your bolt if you shoot a lot.

At this time, our plan is to get a reamer and make up a few barrels and torture test them. I will have to be convinced that the reliability and longevity are there before we start selling them to our customers. We will keep you informed.

I interpret that very clearly as loading to pressure signs on primer/brass (60kpsi+), bolts start having issues with these cartridges. I don't think anybody would disagree with this statement. My disagreement is with the necessity of loading to those pressures.

@Henryrifle to your point, we *choose* to load to the pressures we are comfortable with. This is where I do not agree with WOA's stance, they are effectively stating the cartridge is not useful because loading it hot results in accelerated bolt wear (at least, that's how I read it). Everything in reloading and cartridge selection is about trade-offs. More recoil, larger rifles, less recoil, smaller rifles, more cartridges per magazine, smaller cartridges, etc. The 6mm ARC falls around the 6.5mm Grendel. I think the Grendel is probably a slightly better hunting cartridge and the ARC a slightly better target cartridge. There are plenty of wildcats to go around in the same category, as well, as many seem eager to share.

It's a great balancing point for a general purpose cartridge that can do a lot of things fairly well. It's not the best ELR cartridge, but it isn't intended to be. For a mixed utility varmint to deer hunting / out to 1000 target cartridge it's relatively powder efficient, component cost is relatively low, recoil is mild, barrel life isn't terrible, it can be fired from existing (and very popular) AR15 pattern rifles with a simple barrel/bolt/magazine swap, and it's standardized. We don't all need to fire 108 ELD-Ms at 3200fps out of a 18" barrel, there are obviously better choices for that if that's your goal, but that's not the intent of this cartridge.

I just don't understand tossing out complaints about bolt/barrel extension issues when loading above max specified pressure to achieve higher than design intent performance. If I load a 6.5 CM to 75,000 PSI to try and compete with a larger-cased magnum, it probably won't go well either. Why would you want to? Now if WOA is just saying they don't want to chamber because their customer base is going to push the limits and load well over specified pressure and they don't want to deal with the blow back from broken bolts/extensions, then more power to them. I just think the wording could have been better - that post is cited in nearly every 6mm ARC thread now as evidence it's "doomed", so clearly I'm not alone in my interpretation.

 

[Waco Kid]

Tons of good info here! Interested to see more data from some of the 10-16" barrels. Found out about the arc after finally deciding to build a grendel haha. For now, I don't reload so grendel is a better option for me. Guessing it will need to gain more popularity before more manufacturers jump in, but has anyone heard of more ammo options on the horizon?

 

[Henryrifle]

Totally agree. We are all saying the same thing. 6mm ARC is another new and interesting SAAMI cartridge with its own set of strengths and weaknesses.

And, WOA has a great reputation for making and building competition components, and, at this time, does not want to get involved with this cartridge due to the temptation to hotrod it and the headaches that could bring.

Want to switch back to 6mm ARC happy talk.

@ormandj: It looks like your gas port is half on a land and half on a groove but the pic is blurry. That is where mine ended up. I thought about trying to hit a groove but without a mill, it would have taken some luck. I know there are folks who insist one way is better than another but there has never been any conclusive consensus that that is true. I have an old school Hawkeye borescope and don't think I could take a picture but my gas port has some scary looking erosion after 400 rounds. Nothing unusual but still not fun to look at. Mine was a clean hole to start with no burr resulting from the drilling.

Please go shoot that thing. Now that I am interested in AR-Comp, of course, you can't find it ANYWHERE!!!

Henryrifle

 

[Henryrifle]

Cleaned the 6mm ARC this afternoon and thought I'd put up a pic of the bolt. A little over 400 rounds on it. CFE223 is dirty but pretty easy to clean. Also interesting that gas port erosion has not gotten any worse in the last 150 rounds. Was almost afraid to look.

Bot Pics:

Henryrifle

 

[SBRSarge]

Tons of good info here! Interested to see more data from some of the 10-16" barrels. Found out about the arc after finally deciding to build a grendel haha. For now, I don't reload so grendel is a better option for me. Guessing it will need to gain more popularity before more manufacturers jump in, but has anyone heard of more ammo options on the horizon?

I’m with Waco Kid. I have an 18” barrel on backorder for a longer range affair, but love SBRs too. It would be great to have a truly long range AR15 size gun and also have the SBR in the same cartridge.

I also hope more also companies are tooling up. I don’t reload but would love to see some Barnes TSX and/or TTSX bullets loaded in 6ARC.

 

[jbailey]

***BRASS SUPPLY UPDATE***
Anyone looking for 6ARC brass, the GA Precision Store has a big pile. Order as many as you want at 66cents a pc (50 pc min). I ordered yesterday and its inbound today.

 

[LRBuck]

I will be. Barrels are here just need to go shoot some factory to harvest some brass.

Still patiently waiting for my
barrel .... or trying to. Those barrels look so nice Ormandj !

Anyone doing testing with the 103 ELD X or the Berger 109 LR hybrid? In CFE 223, Varget (for ELD X) or Pwr Pro?

 

[MSTN]

Shot my 18" Proof yesterday for the first time with Hornady 105 BTHP.

2689 FPS.

 

[CarbonMTN]

could you honestly use this for PRS bolt rifle? how does it stand up the the Dasher?

 

[Ledzep]

could you honestly use this for PRS bolt rifle? how does it stand up the the Dasher?

Got a top 10 finish in the last NRL 2-day match I shot with my 28" 6 ARC bolt gun, and top 15 finish in the one before that. In the 28" barrel I'm pushing 105-110gr bullets 2880-2940fps depending on the load/powder I've used. All within (bolt gun) book data.

I'm a fan. Very little recoil, runs great in MDT BR magazines, keeps the barrel cooler than a 6 creed. The only real gripe is actions with bolt faces, and you gotta monitor temp and MV. 4Dof takes care of the temp vs. MV for me though.

 

[Henryrifle]

After calling around today I found a pound of AR-Comp. It looks like that powder is a good bit faster than CFE223. Using the same calibrations I've used for Varget and CFE223, Quickload estimates the maximum charge just at 52K PSI is 24.7 grains. Going to back off of that a bit and see if there is anything there. 24.5 grains looks to make about 50K PSI and 2562 FPS in my 21.75" barrel behind the 108 ELD-M.

Will post results after testing...

Henryrifle

 

[ormandj]

10, 20, and 26 round CPD Duramags. 10.5" and 18" barrel. Picture is with the 20 rd magazine installed.

 

[Henryrifle]

Shot a few groups today to test increased charges of CFE223 and the effect of cooler weather on known charges .

The temperature was 68 degrees, 12 degrees cooler than I have previously shot with this rifle (80 degrees). My baseline charge is 28.3 grains which yields a consistent 2600 FPS +/- 10 FPS and .6 MOA groups +/- .15 MOA in 80 degree weather. Today that same load shot an average of 2568 FPS or 32 FPS slower. with an average group size of approximately 1 MOA. It is probably not a linear calculation but it looks like 2.6 FPS per degree between those two temperatures.

Before changing powders to AR-Comp, I wanted to see what a higher charge of CFE223 would give me. Using Quickload I settled on a 29.6 grain charge under the 108 ELD-M. Quickload estimated 2697 FPS making 50,914 PSI pressure and a barrel time that was very close to a predicted OBT node. I think the pressure may be a little more. All 15 of the rounds I shot at this charge weight had a shiny spot where the ejector was and 5 of them or 33% had slight brass flow around the ejector that I could feel. No primers were excessively flattened and all of them retained a normal-looking radius around the edge. Factory 108 ELD-Match ammo does the same thing in my rifle.

The good news is that the MV was an average of 2715 FPS. SDs were very acceptable for the three groups at 7.1, 12 and 4.8. This equals and slightly betters the MV of Hornady's factory 108 ELD-M Match ammo in my barrel. There was some vertical in all three groups indicating that this is probably not an accuracy node. Reducing the charge by .3 to .5 grains will hopefully fix both the brass flow and the accuracy. Even if that reduces the MV by 50 FPS, I'd be happy with 2660 FPS as that will keep the 108 supersonic out to 1000 with a little speed to spare.

As you'll see in the target below, I did not shoot well today at all. I only pulled one shot and that was the high left shot in the second group so, I am going to chock up the groups to MV being significantly off in the first two groups and not being on the node in groups #3 - #5. There was one scope change between group #1 and group #2.

Hope y'all have a good weekend,
Henryrifle

 

[MSTN]

18" Proof barrel with Hornady factory 105 BTHP:

 

[Yondering]

18" Proof barrel with Hornady factory 105 BTHP:View attachment 7438788

An average of ~2690 fps is not bad at all for an 18". Consider for comparison - my 19" barrel in 243 LBC (just a hair more capacity, I'd guess ~30-40 fps worth at the most) with full tilt Leverevolution loads and the same bullet does 2740 fps at the chrono; only about 50 fps faster. That ES seems a little high, but maybe that's to be expected with some factory ammo? I don't spend much time with factory ammo for precision rifles so I don't really know about that.

 

[Henryrifle]

Good velocity and a great looking rifle! My 21.75" Wilson barrel shoots that same ammo between 2700 and 2707 FPS with SDs between 17 and 21 FPS. How does it group? Mine shoots that between 1.1 MOA and 1.5 MOA at 100. Have not shot that ammo past 100.

Henryrifle