New 6mm Advanced Rifle Cartridge

I was curious about the PRI mags. Saw them mentioned in a couple of threads about seeing if they ran, but there was never any follow up. Thanks
Years ago when we could still buy the Gen1 PRI mags they worked well because they were stiffer than ASC and CPD mags and did not bulge, now the Gen 3s have a different feed lip angle, I don't think they work as well as the old Gen 1s.
 
Capacity doesn't matter they're all the same design. I believe they offer 5, 10, 15, 25.
That’s not how magazines work. Different capacities will perform differently due to geometry and springs. Lower capacity magazines are almost always much easier to get to function properly than higher capacity.

Either way, I bought a few of all the capacities I could find to try out to compare with my Duramags.
 
That’s not how magazines work. Different capacities will perform differently due to geometry and springs. Lower capacity magazines are almost always much easier to get to function properly than higher capacity.

Either way, I bought a few of all the capacities I could find to try out to compare with my Duramags.
IIRC the Gendel horde always had problems with the 17 round mags but you can go to the Grendel forum and find the posts.
 
I'll vouch for the Noveske SS barrels.
Not a 6ARC, but my 12.5" 6.5G shoots impressively with ELD-M's.
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Finally wound up taking this advice and ordering an 18", RLGS lightweight profile barrel from X-Caliber during their Memorial day sale. Hopefully it comes in time to get a couple loads worked up for deer season.

Came in about 6 weeks, fit and finish looks excellent for the price, if it shoots I think it will make a good little general purpose/deer whomping carbine. I'm in the middle of setting up another rifle right now so I'll probably build the upper next month and see what it likes from the 6mm hunting bullets I have around (95gr SST, 85gr SGK, 108gr eld, and 100gr TGK on the way).
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Has anyone used a Surefire socom762-ti2 or a socom300-sps suppressor with the 6ARC?

I have shot mine with a 762RC2, 300SPS, and 260Ti. My 300Ti is still in jail. RC2 definitely shot the best and was the quietest. The 300 SPS was second but you tell it was a little gassier, but not by much still sounded good. The 6.5Ti was the loudest and the most back pressure. But, that is to be expected from the SF Ti cans. Since they are meant for bolt guns.
 
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Anyone running a 22-24" 6arc in an ar? Looking at the ballistic advantage 24" dmr barrel, it's 1/7 twist which should be good to run some berger 109lrht through. Looking to see if anyone has some experience running a similar setup, wondering if you'd do it again, or maybe go to a 20-22" over the 24". I would really like to see 2700fps-2800fps.

The main purpose would be for gasser prs type shooting. Chances are i'll run some factory loads for a bit then start hand loading.
 
Anyone running a 22-24" 6arc in an ar? Looking at the ballistic advantage 24" dmr barrel, it's 1/7 twist which should be good to run some berger 109lrht through. Looking to see if anyone has some experience running a similar setup, wondering if you'd do it again, or maybe go to a 20-22" over the 24". I would really like to see 2700fps-2800fps.

The main purpose would be for gasser prs type shooting. Chances are i'll run some factory loads for a bit then start hand loading.

I have a 22" Shaw barrel. I'm happy with it. I get around 2700 fps from factory Hornady ELD-M and a little more from handloads with Berger 109s. If I load the Bergers out near the COL limit of the magazine, it's very precise.
 
Anyone running a 22-24" 6arc in an ar? Looking at the ballistic advantage 24" dmr barrel, it's 1/7 twist which should be good to run some berger 109lrht through. Looking to see if anyone has some experience running a similar setup, wondering if you'd do it again, or maybe go to a 20-22" over the 24". I would really like to see 2700fps-2800fps.

The main purpose would be for gasser prs type shooting. Chances are i'll run some factory loads for a bit then start hand loading.
I am running a 24" with a 1:7. I chose that length for my own purpose and the same thing with the twist rate.

I'm not running my loads super hot at all. In fact I run a really mild load. My velocity is pretty mild but I purposely chose a node with more precision. I think I am getting right at 2650 I think but like I said I chose precision over velocity. I have at least another 100fps in the gas tank should I decide to do that.

I had the plan to shoot heavy bullets in mine so I went with the 1:7. I don't think it was a mistake by any means but rather overkill. I'm of the school that twist should be a function of length. A 24" barrel with a 1:8 twist would I assume stabilize up to 110 grain bullets. As of right now my 1:7 cut off some of the lighter bullet options (which I personally will never shoot anyway so absolutely nothing was lost in my book).

If you were to go with a shorter barrel then definitely a 1:7 would be great. In general though twist rate is really nothing to split hairs over. At a certain point it's good enough.

I've never been able to find any 115 grain bullets to try but the 112 grain match burners didn't shoot well at all.

Personally I got a 24" barrel on purpose. I wanted the opportunity to shoot longer ranges and to have the most opportunity for nodes. Like I said, I really backed off my load data a lot.

If you are only shooting within 800 yards or something like that there is no need to get a 24" barrel, at least no technical reason for it.

It just depends on what you want out of the gun.
 
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Anyone running a 22-24" 6arc in an ar? Looking at the ballistic advantage 24" dmr barrel, it's 1/7 twist which should be good to run some berger 109lrht through. Looking to see if anyone has some experience running a similar setup, wondering if you'd do it again, or maybe go to a 20-22" over the 24". I would really like to see 2700fps-2800fps.

The main purpose would be for gasser prs type shooting. Chances are i'll run some factory loads for a bit then start hand loading.
My experience is similar to @TripleBull.
Gun is set up for PRS type shooting.
22” Rainier UM 7T. Just got back from the range. It was 96 degrees & heat index over 100 so I was a little worried about the Lever. Especially since I was trying to find upper end loads. Using Lever the SD’s don’t seam to get happy till the top end.
No issues with brass at all.

Edit: All these loads below except 95 Senecas are top end that I worked up to albeit in cooler temps.

109 Berger loaded 2.290/1.735 with 29.8 Lever = 2732 & SD of 6.7 for 8 shots.
108 eldm 2.270 29.8 Lever = 2780 SD 7.4
105 berger Hyb @ 2.270 30.0 Lever = 2782 SD 7.0
100 TGK @ 2.250 with 30.5 Lever = 2851 SD 3.8
95 Berger VLD @ 2.27 with 30.7 & 31.0 mixed the 2 on Chrono but combined avg = 2933 SD 12.8
All above was Lapua brass. Necks measure +.002 on loaded round & it holds tighter groups vs Hornady brass in my rifle.

Hornady Brass was shooting triangle holes and scattering 100g PVA Senecas so I figured I’d try worst case brass wise for the 95 Senecas.
Hornady Brass
95 Seneca @ 2.372 windowed mag fed 30.7 Lever
=2847 SD 24.5
All holes round even down at 2812 with 30.1g
Despite the shitty SD I shot 4 of the 2847 loads at steel @400y. 1st shot was over the plate using .281 G7 in Kestral. Hell kestral spit out 1.9 for 400, I dialed 1.8 & was over the plate holding center (10” plate). Held bottom plate & hit .4 mill high. Put 3 in 3” @ 400 shooting fast, but I need to get that SD way down. Lapua brass next time now that I know there stable.
 
Anyone running a 22-24" 6arc in an ar? Looking at the ballistic advantage 24" dmr barrel, it's 1/7 twist which should be good to run some berger 109lrht through. Looking to see if anyone has some experience running a similar setup, wondering if you'd do it again, or maybe go to a 20-22" over the 24". I would really like to see 2700fps-2800fps.

The main purpose would be for gasser prs type shooting. Chances are i'll run some factory loads for a bit then start hand loading.

Mine are 243 LBC (6mm Grendel variant) wildcats from long before there was a 6 ARC, but more or less the same thing. One of them is a 24"; IMO if you're doing a 22", you might as well just go 24" at that point. I'd definitely go 24" again, but I kept mine a reasonable barrel profile and a light sleek handguard, so the rifle doesn't feel huge and awkward.

I don't think you should expect to get a 109 to 2800 fps though, even with Lever. I was pushing the 105 BTHP to ~2840 before there was any load data, but have backed it off to about 2800. You won't hit that speed with a 105 at sane pressures with any other powder though IME, and pushing a 109 to that would be hotter than the brass or bolt would tolerate I think. 2700 would be a fairly stiff load but maybe do-able with Lever. Make sure you've got full and even bolt lug contact if you're pushing it hard like that. (Squaring the receiver face helps with this btw.)
 
Mine are 243 LBC (6mm Grendel variant) wildcats from long before there was a 6 ARC, but more or less the same thing. One of them is a 24"; IMO if you're doing a 22", you might as well just go 24" at that point. I'd definitely go 24" again, but I kept mine a reasonable barrel profile and a light sleek handguard, so the rifle doesn't feel huge and awkward.

I don't think you should expect to get a 109 to 2800 fps though, even with Lever. I was pushing the 105 BTHP to ~2840 before there was any load data, but have backed it off to about 2800. You won't hit that speed with a 105 at sane pressures with any other powder though IME, and pushing a 109 to that would be hotter than the brass or bolt would tolerate I think. 2700 would be a fairly stiff load but maybe do-able with Lever. Make sure you've got full and even bolt lug contact if you're pushing it hard like that. (Squaring the receiver face helps with this btw.)
See, i want a heavier contour barrel, part of the reason i like the ballistic advantage 24”. Thank you all for your input, i’ll be ordering the 24” ballistic advantage.
 
See, i want a heavier contour barrel, part of the reason i like the ballistic advantage 24”. Thank you all for your input, i’ll be ordering the 24” ballistic advantage.
If You have the budget. I’d highly reccomend getting the Craddock signature 22” Bartlain gain twist 8-7.25 heavy profile .875 GB. They are in stock $585.00
 
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If You have the budget. I’d highly reccomend getting the Craddock signature 22” Bartlain gain twist 8-7.25 heavy profile .875 GB. They are in stock $585.00
I’m not sure I’ve heard of gain twist before. Looks like I learned something new and have some research to do.

Do they give discernible benefits?
 
I’m not sure I’ve heard of gain twist before. Looks like I learned something new and have some research to do.

Do they give discernible benefits?
Gimmick IMO. Think about it, the bullets are engraved at the start then the twist changes and enlarges the grooves in the bullet.
Again MO but you would be better off finding a barrel with the correct bore area, perfect .243 dia and thin lands for a 25:75 land to groove ratio.
We have done enough testing to know tight bores and oversized bullets will produce slower velocity with cases that have a small capacity like the 6.8 and Grendel sized case.
 
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Gimmick IMO. Think about it, the bullets are engraved at the start then the twist changes and enlarges the grooves in the bullet.
Again MO but you would be better off finding a barrel with the correct bore area, perfect .243 dia and thin lands for a 25:75 land to groove ratio.
We have done enough testing to know tight bores and oversized bullets will produce slower velocity with cases that have a small capacity like the 6.8 and Grendel sized case.
Thanks Constructor. Your argument makes a lot of sense, esp. about the enlarged groove from the changing twist.
 
Now that all my parts came in I was planning on assembling my lightweight upper this weekend.

Before starting I tried inserting some of the 108gr and 105gr Hornady factory loads I have, by hand, into the chamber of my X-Caliber barrel and found that they were getting stuck in the chamber. I had to poke them out with a cleaning rod (although they weren't hard stuck), but I'm seeing marks from the lands on the bullets.

I'm thinking I have a short throat that probably needs to be reworked by X-Caliber. Am I missing anything obvious here? The rounds will chamber and disassembled bolt will rotate and lock in the recesses, but I'm not used to seeing factory loads into the lands.
 
Now that all my parts came in I was planning on assembling my lightweight upper this weekend.

Before starting I tried inserting some of the 108gr and 105gr Hornady factory loads I have, by hand, into the chamber of my X-Caliber barrel and found that they were getting stuck in the chamber. I had to poke them out with a cleaning rod (although they weren't hard stuck), but I'm seeing marks from the lands on the bullets.

I'm thinking I have a short throat that probably needs to be reworked by X-Caliber. Am I missing anything obvious here? The rounds will chamber and disassembled bolt will rotate and lock in the recesses, but I'm not used to seeing factory loads into the lands.
I remember hearing some of the early factory loads were into the lands & causing some issues. Is this early lots of ammo?
 
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If the 105's are at 2.250 it's the first production lot. Hornady will replace them if that's what you have. Subsequent lots have been in the 2.20" range.

108's shouldn't stick.
Thanks, that's what I thought I recalled, that only the very first batches of 105gr were too long and that later batches and all the 108gr were not affected. Just measured the 105gr and they are right around 2.20", so it doesn't seem like an ammunition problem.
 
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Finally played with my 18” proof SS, Seekins Irmt-3 build a little bit.
Ram some factory Hornady 108 and 105 to zero and tune. About 2650fps avg on both loads and 1/2-3/4” groups right off the bat.
I started load testing with cfe223 and 108 eld seated to the same depth as factory. I ran up to 30gr just to see what it looked like. No obvious pressure signs on the brass but I don’t think I’ll load past about 29.3 as that gave me about 2650 fps like the factory ammo.

Loaded more at 28.3 because the pressure ladder stacked 28-28.6 in the same poi. 28.3 is a 2540avg but it bugholes more often than not. First round always seems to go low for so I’ll have to experiment on that. I’m going to load up more to run for the first 200rds or so and revisit load development later. Maybe I should grab a bottle of lvr to test.

Like others have said a 18” with a RL +1 needs the gas block almost all the way open. I put an slr on it because I had one in the parts box. Need to do further tuning to see if I can find a happy place where it runs with a brake or 762sd. Tubb spring and im using a a5h0 unsuppressed and a5h2 suppressed for now. It doesn’t move at all with a A419 match brake.
 
750 yds, calm, sent one right over the top of the 12x12 plate but the other 4 are right there. About 50rds on the barrel so I think there’s definitely potential here.

Amp annealed and resized 1x hdy 6.5 grendel brass, trimmed, chamfered and run over a mandrel
108 eldm seated to factory ammo oal
#41 primer 28.3 cfe223

18” proof SS, slr adjustable gas block
Seekins receivers, Irmt-3 upper and rail
TT Diamond
Tubb spring and a5h0 buffer

Seems to run ok suppressed or with a 419 brake. Gas block is completely open and leaking a bit so I’m probably going to swap to a fixed block and as it breaks in further I may end up at a a5h1 buffer.

I need to pick up a few lbs of lvr since that seems to be the hotness for the Arc.
 

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Thanks, that's what I thought I recalled, that only the very first batches of 105gr were too long and that later batches and all the 108gr were not affected. Just measured the 105gr and they are right around 2.20", so it doesn't seem like an ammunition problem.
It would seem that my hand wringing over throat length was unjustified, and now that I've shot this X-Caliber barrel some, I think it's going to be a winner. Factory 108gr are right at the lands, and 105gr is a little bit into the lands, but not enough to cause problems.

It likes the 108gr factory and I've worked up a 100gr TGK load with little effort. I had a spread of 108gr loads ready today and managed to fumble and tip over the box spilling most of them.... Like a moron. Still I had two of each load ( 28.8, 29.1, 29.3, 29.5) I was sure about, and it looks like 29.3 - 29.5 will be the area to focus on next time.

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Put together a lightweight upper with a 16" Faxon match series barrel, just for a truck gun and blasting coyotes. Appears to be the best shooting Faxon barrel I've had so far. 10x 108s at 100. 1.09" center to center.

Adjustable gas necessary with the midlength tube and a can.

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That’s pretty impressive for a Faxon. I’d kind of written them off With regards to precision. Assuming it’s got their std Nitrite treatment, it should have great barrel life.
 
That’s pretty impressive for a Faxon. I’d kind of written them off With regards to precision. Assuming it’s got their std Nitrite treatment, it should have great barrel life.

Yeah me too. Almost every one Ive seen had the throat off-center from the bore, caused by an undersized bore bushing on the reamer and chasing production speed too far. That alone is pretty bad for accuracy.
 
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Anybody tried reloading heavier bullets (105-109g) with RL-15.5?
Johnny's tried that combo. Pressured out without delivering good speed.
I have not tried it in ARC & doubt I will. Did give it a try in 224 Valk & had sim results to Johnny. Pressured out @ low speed & tore up brass.
Cant fit enough in 223 to hit pressure. 77's went 2650 at 25gr (very compressed).
6.5 Creed with 130's 15.5 is excellent. I posted results in the 6.5 Creedmoor thread. https://www.snipershide.com/shooting/threads/6-5-creedmoor.89643/post-10442169

 
Okay so I signed up for my first AR precision rifle comp in November and am going to run my 18” 6 ARC in it. So far I have only been plinking for fun with it and haven’t done any load development.

What is the general consensus for the best bullets to use? I’ve been getting Hornady 105 bthp so far and using converted starline brass.
 
Okay so I signed up for my first AR precision rifle comp in November and am going to run my 18” 6 ARC in it. So far I have only been plinking for fun with it and haven’t done any load development.

What is the general consensus for the best bullets to use? I’ve been getting Hornady 105 bthp so far and using converted starline brass.
What range will the match be??
 
Ranges out to about 700 yards
I'd probably go with 105 hybrids, but I've got a 22" barrel.

Berger 95 VLD's would work well in your 18" to 700. They have been available and I can push them 150fps faster than the 105's in mine.

See post #2529 this thread for these loads. I worked up & these were top end loads.
 
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If You have the budget. I’d highly reccomend getting the Craddock signature 22” Bartlain gain twist 8-7.25 heavy profile .875 GB. They are in stock $585.00
Well I bought one. See how it does in a couple weeks.
Going to move the Rainier barrel to a Aero M4E1 enhanced with Sgt of arms arca rail & put this Craddock in the Vltor Fushion.

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I'll add another data point for the group. I put the first rounds downrange last night with a new rifle. Barrel is a Compass Lake Engineering 22" 7.5 twist from a Criterion blank, +1 rifle length gas. 24 rounds total. A quick 3 shot group of Hornady Black 105 bthp factory ammo yielded a .42" group at 100 yards. The next groups were 5 shot groups with Hornady 108 ELDM factory ammo.... First was .86" and the next was .66". Velocity of the 108s averaged 2702 and the 105s were just under 2700 fps. Chrono is a Labradar and all groups were shot suppressed. So far it looks very promising for accuracy.
What contour and gas block size are you running? Thx
 
What contour and gas block size are you running? Thx
It's a varmint profile and 0.875" at the gas block. I'm just over 600 rounds now and accuracy with 105 and 108 factory ammo is consistently 1/2" 5 shot groups at 100. The little load development I've done with Lever and 107 SMKs shot around 0.6" and single digit SD. I'm pretty pleased with the barrel.
 
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