New 6mm Advanced Rifle Cartridge

Very promising at first. Single loading the magazine, the very first 8 shots down the barrel went around 0.8 MOA - even while I was adjusting the gas block!

The first E-Lander 17-RD magazine I was using proved to be a problem if loaded to capacity, with bullet tips jamming into the front of the magazine body, totally crushing the bullet tip, and likely causing bullet set back plus concentricity issues at the same time. Even with a blown rotator cuff, I was amazed at how far I was able to throw it.

A second E-Lander magazine when loaded full functioned normally, but groups were a disappointing 1.2 MOA - 1.3 MOA. The borescope showed a super rough gas port erosion beginning, with a streak of copper going forward.

Sadly, I see this frequently with brand new SS barrels. The barrel should settle back down to its accuracy potential in another 50-100 rounds.
 
I'll be really interested to know what length and kind of barrel the first person who says they shot factory ammo into a .5 MOA group. My experience has been a little worse than yours though the SDs of the factory ammo have been reasonable with the 105 Black and single-digit-good for the 108 Match.

I shot some groups with CFE223 at 29.3 and 29.5 grains. The temperature was a little warmer than I expected at 70 degrees making more MV than I expected. 2709 for the 29.3 and 2725 for the 29.5. There was some ejector flow on the cases loaded to 29.5. Looks like 29.0 or 29.1 will be safe for the next few months and should shoot in the high 2680-2690 range our of my 21.75" barrel. Groups were nothing to write home about at 1.05 and .99.

Still want set up some tests with AR-Comp but prepping for competition this weekend.

Henryrifle
 
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I'll be really interested to know what length and kind of barrel the first person who says they shot factory ammo into a .5 MOA group. My experience has been a little worse than yours though the SDs of the factory ammo have been reasonable with the 105 Black and single-digit-good for the 108 Match.

I shot some groups with CFE223 at 29.3 and 29.5 grains. The temperature was a little warmer than I expected at 70 degrees making more MV than I expected. 2709 for the 29.3 and 2725 for the 29.5. There was some ejector flow on the cases loaded to 29.5. Looks like 29.0 or 29.1 will be safe for the next few months and should shoot in the high 2680-2690 range our of my 21.75" barrel. Groups were nothing to write home about at 1.05 and .99.

Still want set up some tests with AR-Comp but prepping for competition this weekend.

Henryrifle

I'm hoping to have some info soon. Just waiting on a scope mount, I had a Bobro that had a fastener fail this morning while attaching to the rifle (20k+ rounds on a SCAR17 will do that...), so have an ADM Recon OTW. I'd really prefer not slap a ZCO 527 on a 10.5" barrel rifle, that'll be a little silly.
 
@ormandj: I have been waiting what seems like a month of Sundays for some data from you :) I'd be happy if you duct taped a Celestron C5 spotter on there. Come on man...

Haha, that's how I felt waiting on my barrels! Literally got them this Saturday, got the rifles together, and now waiting on broken part replacements. I assure you, it will be soon! If nothing else, I'll go out with iron sights and my LabRadar and at least get some velocity data.
 
Very promising at first. Single loading the magazine, the very first 8 shots down the barrel went around 0.8 MOA - even while I was adjusting the gas block!

The first E-Lander 17-RD magazine I was using proved to be a problem if loaded to capacity, with bullet tips jamming into the front of the magazine body, totally crushing the bullet tip, and likely causing bullet set back plus concentricity issues at the same time. Even with a blown rotator cuff, I was amazed at how far I was able to throw it.

A second E-Lander magazine when loaded full functioned normally, but groups were a disappointing 1.2 MOA - 1.3 MOA. The borescope showed a super rough gas port erosion beginning, with a streak of copper going forward.

Sadly, I see this frequently with brand new SS barrels. The barrel should settle back down to its accuracy potential in another 50-100 rounds.
Give it some time and that new elander will have you chucking it down range too...
 
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.

I haven't followed this thread or the 6ARC but this seems like a pretty neat little cartridge.

Why did you go for it in your bolt gun over say a 6br?
Looks like the 6br would offer a touch more velocity with the inherent accuracy that 6br is known for.

What swung you towards the ARC?
 
I haven't followed this thread or the 6ARC but this seems like a pretty neat little cartridge.

Why did you go for it in your bolt gun over say a 6br?
Looks like the 6br would offer a touch more velocity with the inherent accuracy that 6br is known for.

What swung you towards the ARC?
Best guesstimate, factory ammo available if don't have time to load or just want to do some shooting that can run "good enough" ammo.
 
I haven't followed this thread or the 6ARC but this seems like a pretty neat little cartridge.

Why did you go for it in your bolt gun over say a 6br?
Looks like the 6br would offer a touch more velocity with the inherent accuracy that 6br is known for.

What swung you towards the ARC?

I built an 18" hunting rifle (CZ 527) and had a contact that got me some early 60-62ksi data. Figured I already had brass and the velocity extrapolation looked good so I thought "what the hell, I'll try the damn little thing". Factory ammo will (eventually, once/if everything calms down) become more available, bore area vs. case capacity is about like a .223 so barrel life should be great, very minimal recoil, and acceptable velocity. It's worked out a lot better than I expected. I explain it to most folks that it's a 6.5 creedmoor trajectory with no recoil.

If I had my cake and could eat it too, I'd like someone to make 6 BRX brass without fire/hydro forming being necessary... But the ARC certainly works for now.
 
bore area vs. case capacity is about like a .223 so barrel life should be great, very minimal recoil, and acceptable velocity. It's worked out a lot better than I expected.

Actually the 6ARC in more underbore than 223 so the barrel life should be a non-issue.
Those speeds you are getting are very good, better than some 6BR loads which typically burn more powder.

This 6ARC sounds like a winner to me.
Shame they didn't do a rebated rim as I now what to re-barrel my 223.........
 
Actually the 6ARC in more underbore than 223 so the barrel life should be a non-issue.
Those speeds you are getting are very good, better than some 6BR loads which typically burn more powder.

This 6ARC sounds like a winner to me.
Shame they didn't do a rebated rim as I now what to re-barrel my 223.........

Yeah the case volumes on the BR and the ARC are pretty similar. I'd bet if guys would try LeverEvolution in the BR they'd be surprised by the velocity they can get. If you try to run H4895, Varget, or 8208 you'll get the temp stability back, but lose 150fps. Still not the end of the world, though. 2750-2800 with a 110 is plenty capable for matches. On the flip side with the spherical powders, I just do temp tests at 40 and 100 degrees and find the fps/degree factor to plug into 4DoF and let it handle it for me.
 
Yeah the case volumes on the BR and the ARC are pretty similar. I'd bet if guys would try LeverEvolution in the BR they'd be surprised by the velocity they can get. If you try to run H4895, Varget, or 8208 you'll get the temp stability back, but lose 150fps. Still not the end of the world, though. 2750-2800 with a 110 is plenty capable for matches. On the flip side with the spherical powders, I just do temp tests at 40 and 100 degrees and find the fps/degree factor to plug into 4DoF and let it handle it for me.

One can only hope for a 6.5 StaBALL that's better suited for this class of cartridge. I shoot a lot from memory (use a Kestrel to get dope for the day's environment, memorize the table), so doing the temperature math in-head for various distance targets doesn't work out. Temperature stable powders make this (mostly) a non-issue, since I know the drop/windage to use at 600yds, for example. Factor in temperature coefficients and my internal memory isn't large enough. :)
 
Was at the range today practicing for a match this weekend and decided to squeeze in a few groups of 6mm ARC. The temperature was 75 degrees, presenting a good opportunity to test 29.0 grains of CFE. I started off with the slower 28.3 grain load that has consistently shot in the .7s.

The first two groups were shot at this charge weight and in an attempt to explain the first group, the barrel was cold and I had just shot dozens of rounds using a trigger that breaks at less than 5 ounces. No excuse for poor shooting but I do acknowledge that my shooting was pretty sloppy.

The next four groups, 3 - 6, were the 29.0 load. The average MV of the four groups was 2662 FPS, good enough to remain supersonic in even at near-sea-level atmosphere we have here in Georgia. There were no pressure signs on the primers and no swipes or bright spots on the brass.

Going to continue testing with this charge weight as it meets the MV criteria and shows some promise of accuracy (maybe). The average group size of the 4 groups is .86 MOA. Nothing to write home about, but worth the investment in components and time if it can be improved.

Very impressed with the muzzle velocity CFE generates. I sure wish it was temperature stable but, I am building a spreadsheet that will greatly assist in matching appropriate loads to expected temperatures.

Henryrifle

Target and data below:
10-7-2020_6mmARC.jpg
 
CFE223 has let me down too many times, where it shoots nicely but groups go to crap when the weather changes (hotter or colder). Leverevolution hasn't done that for me. I don't know why, since they are supposedly similar powders, but they're definitely not the same.
 
CFE223 has let me down too many times, where it shoots nicely but groups go to crap when the weather changes (hotter or colder). Leverevolution hasn't done that for me. I don't know why, since they are supposedly similar powders, but they're definitely not the same.
Do you have suggestions for other powders if you can’t find Lever?
 
I managed to get out to the range, just using an LVPO for now, so no group to upload, as I was just sighting in the rifle. I did capture some velocity data for the 108 ELD-M factory ammunition though (keep in mind this is a brand new barrel, less than 10 rounds through when I shot these):

18" barrel (suppressed):

2641
2642
2642
2643
2652
2640
2640
2646

AVG: 2643.25
SD: 4.026696626

10.5" barrel (suppressed):

2343
2319
2313
2335
2312
2336
2287
2329
2301
2318
2322
2327
2318

AVG: 2320
SD: 15.0443788

This data was acquired using a LabRadar. I apologize in advance for the odd shot-string counts, I was in a hurry and just wanted to get some rounds downrange to start the break-in period and get some velocity data to work up some dope charts to start with until the barrel is fully broken in.

Groups were fine as you'd expect for a Bartlein barrel (inch or so 10 shot groups), but the LPVO (Razor G3 1-10x24) has a 0.2MRAD dot and the barrel wasn't broken in, so I wasn't shooting for groups. I'll dial down a mil and use the ranging reticle to shoot for groups when I get to my primary range and take them both out to 1000 yards and grab some pictures then. Being Craddock Bartlein barrels, and bedded using SS shim stock in my uppers, I fully anticipate these will be shooters.

I also expect both barrels to speed up a little. Hope this provides some useful data to those contemplating an SBR in this caliber. At the average velocity above for the 10.5" barrel, it's still moving at 1235fps @ 800 yards, 1129 fps @ 900, and is at 1063 fps @ 1000. I'm generally fine > 1100 fps and definitely fine above 1200. Depending on the bullet and how it handles the trans-sonic region, I bet 1000 is going to be doable with the SBR. The 18" is around 1236 fps @ 1000 yards, so no problem at all with the longer barrel. This at 70F @ sea level, the numbers will change slightly depending on environment.

@Henryrifle sorry on the delay, but I promised I'd deliver. :)
 
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My experience with the 24" 6.5 Grendel seem to indicate that it doesn't like hot loads (above book maximums). I think the added dwell wth the 24" increases stress on the extractor.

I went .1gr over the published max and got a broken extractor for my troubles. Since repaired with a JP Improved Grendel Extractor, I'll be staying below max loads in the future.

YMMV.

I have a 20" in the same chambering and it just keeps on keepin' on.

Greg
 
@ormandj: That data looks good from the 108s especially so, knowing that your barrels will speed up 20. to 30 FPS. I do want to understand the shim comment. Are you making reference to shims between the barrel extension and upper or do you mean the shim trick between the front pivot lug and lower? Guessing you mean the interference fit between the barrel extension and upper?

Under the category of "some people are never satisfied," I am looking forward to hand load data--especially AR-Comp.

Good data!

Henryrifle
 
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@ormandj: That data looks good from the 108s especially so, knowing that your barrels will speed up 20. to 30 FPS. I do want to understand the shim comment. Are you making reference to shims between the barrel extension and upper or do you mean the shim trick between the front pivot lug and lower? Guessing you mean the interference fit between the barrel extension and upper?

Under the category of "some people are never satisfied," I am looking forward to hand load data--especially AR-Comp.

Good data!

Henryrifle

My lower has a built in screw-driven pivot-pin tightening mechanism, so I was referring to shimming between barrel extension and the upper. They were a tight fit already (couldn't tighten them by hand), so I froze the two barrels, made shims out of 0.001" SS for the extensions, heated the uppers and drove the barrels in place. It's an interference fit at this point, which imo is better than the good ole' green loctite trick, but not permanent. I also turned the faces of the uppers on a lathe, so there's no excuse for poor groupings when I get out and shoot other than myself.

I'll definitely get you load data once I get to that stage, especially with AR-Comp. I have 8lbs of CFE223 sitting around so I might try it too for plinking/making training ammunition until I burn through it, but AR-Comp will be my first attempt at an 'accuracy' load. I'll give up some velocity to get stability, and I don't know of any powder more temperature stable than AR-Comp - and I've got a bunch of Varget sitting around that I'm including in that comparison. I need to get my optic/mounting situation squared away before I start load workup. I think the LPVO w/ a different mount coupled with using the reticle 1mil below the 'dot' should work fine, 10x should be enough for small groups at 100. A ZCO 527 would look awfully silly on the SBR to do load workup...

Did you ever get a chance to give AR-Comp a shot? I'm curious to see how you get along with it, as well.
 
When I built my 24" 6.5 Grendel, I turned the Upper Face, then applied Loc-Tite Red as a filler in the Upper where the extension is inserted.

There is some dispute whether such an Upper can later release the barrel for replacement. Personally, I don't really care. The cost for a stripped Upper is so reasonable that I believe I can afford to sacrifice the original upper.

Lurking in the wings is a 20" barrel, identical to the one in my other, factory built Upper. If a necessity arrives, I can convert the 24" so there are two 20" with literally identical barrels to employ as needed. The 20" shoots the factory fodder nicely enough, but the 24" looks like it's going to need some load tuning.

Whatever...

I've been setting up test loads with 120gr Speer Gold Dots and IMR-8208XBR, W748, and TAC.

Weather has finally started dropping down below 100 degrees (107 days above 100 this year as of today, and the next two are forecast over 100 too.) We are on track for at least 110 days this year over 100 degrees, before week's end. We Elder Farts have troubles handling that kind of heat.

Greg
 
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Do you have suggestions for other powders if you can’t find Lever?

Sorry for the late reply; but no I don't, if you're looking for top velocities with good consistent accuracy. A number of others give good accuracy while sacrificing velocity, there are a fair number of choices there.

One that surprised me was Varget; it gives reasonably good velocity, 50-60 fps slower than Lever at the top end, but shot like absolute garbage with every load I tried for the 105gr BTHP Hornady.
 
In stock Ammo fyi
 
if you need it in hurry from grafs, be prepared to wait, i just got my 3 boxes of 105 black and it took 12 days...from mid-missouri to suburban chicago
in that time i've ordered and received 4 orders from powder valley, midwayusa and natchez in 3 days or less
 
You either need to send that ammo back to Hornady to be resized or you can do it yourself. The first two batches Hornady sent out were 2.245 to 2.250 OAL. The new spec for this ammo is 2.200. If you do not resize it the ammo will push into the lands.
 
1018202221-1 (002).jpg


OK,
finally got my 6ARC together and found time to shoot it. 20" 7-twist Rock Creek from Craddock Precision. Seekins Precision upper, and fore rail. Magpul UBR. My Palmetto State "VA-15" lower (Thanks Gov Northam). And a 3-15x Premier Tac. I duracoated most of it MagPul FDE.

Reloading w/ RL15 and 2000MR. CCI #41 primers, at OAL of 2.25", using the 105gr Berger Hybrid. Temp 67*F.

RL-15:
27.6gr: 2492fps, 8 StDev.
28.0gr: 2557fps, 18 StDev.

2000MR:
29.1gr: 2578fps, 13 StDev.
29.6gr: 2596fps, 10 StDev.

This are the first 20 rds thru the barrel. All groups were printing 0.75"-ish groups at 100yds.
Unfortunately, the 29.6gr 2000MR load showed clear signs of pressure... so its out; the 29.1gr is the top and might be too hot too.

I did shoot at some steel 300 to 400 yds and it was nice to experience the low recoil. This thing is a major upgrade over my 223 AR although not sure its that different than the 6.5G I had 7+yrs ago.

I'm going to try lighter bullets - 90-95gr - as I'm using this as a farm critter guy and don't want a rainbow trajectory.
 
FWIW, I shot my first 6 ARC Saturday.
16” Faxon/Brownells barrel, Vortex Diamondback (I think 2.5-10).
Rifle belongs to a friend of mine. I shot a 5 round group at 200 yards (it’s the 5 holes to the NE side of the big diamond), Hornady Factory 108 ELD ammo, somewhere right at 2”.
Given the barrel only has somewhere less than 50 rounds on it, factory ammo, and me behind the buttplate, I was pretty impressed.
6258BADC-7364-440B-87F2-179AE1D6D5EC.jpeg
 
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View attachment 7448864

OK,
finally got my 6ARC together and found time to shoot it. 20" 7-twist Rock Creek from Craddock Precision. Seekins Precision upper, and fore rail. Magpul UBR. My Palmetto State "VA-15" lower (Thanks Gov Northam). And a 3-15x Premier Tac. I duracoated most of it MagPul FDE.

Reloading w/ RL15 and 2000MR. CCI #41 primers, at OAL of 2.25", using the 105gr Berger Hybrid. Temp 67*F.

RL-15:
27.6gr: 2492fps, 8 StDev.
28.0gr: 2557fps, 18 StDev.

2000MR:
29.1gr: 2578fps, 13 StDev.
29.6gr: 2596fps, 10 StDev.

This are the first 20 rds thru the barrel. All groups were printing 0.75"-ish groups at 100yds.
Unfortunately, the 29.6gr 2000MR load showed clear signs of pressure... so its out; the 29.1gr is the top and might be too hot too.

I did shoot at some steel 300 to 400 yds and it was nice to experience the low recoil. This thing is a major upgrade over my 223 AR although not sure its that different than the 6.5G I had 7+yrs ago.

I'm going to try lighter bullets - 90-95gr - as I'm using this as a farm critter guy and don't want a rainbow trajectory.
[/QUOTYE]
Very Nice. Still waiting for my 22” Rock Creek from Craddock. Anxious to hear about your lighter grain loads too.

How long ago did you order from Craddock? I ordered in July and trying so hard not to be the kid who can’t wait for Christmas morning!
 
Very Nice. Still waiting for my 22” Rock Creek from Craddock. Anxious to hear about your lighter grain loads too.

How long ago did you order from Craddock? I ordered in July and trying so hard not to be the kid who can’t wait for Christmas morning!

@LRBuck
I ordered from Craddock in late June, so your order should be close.
I wish I had gone 22" over the 20"... that 50fps would be nice to have and I would never notice the extra 2".
 
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An average of ~2690 fps is not bad at all for an 18".

For the sake of discussion on velocity, I get 2900fps exactly using a Proof Carbon Barrel with 90g Gold Dots and factory ammo out of my 6.8. I'm 3.7mils to 500 yards and 264ftlbs of energy. Anyone have comparable data for their 6 ARC w/ 18" barrel at 500 yards? @MSTN

Once my 6.8 Stock is gone, most nearly going with a 6 ARC.
 
For the sake of discussion on velocity, I get 2900fps exactly using a Proof Carbon Barrel with 90g Gold Dots and factory ammo out of my 6.8. I'm 3.7mils to 500 yards and 264ftlbs of energy. Anyone have comparable data for their 6 ARC w/ 18" barrel at 500 yards? @MSTN

Once my 6.8 Stock is gone, most nearly going with a 6 ARC.
Want 80 / 85 / 90 gr bullet?
There are ways to get those bullet weights from "factory" ammo.
 
For the sake of discussion on velocity, I get 2900fps exactly using a Proof Carbon Barrel with 90g Gold Dots and factory ammo out of my 6.8. I'm 3.7mils to 500 yards and 264ftlbs of energy. Anyone have comparable data for their 6 ARC w/ 18" barrel at 500 yards? @MSTN

Once my 6.8 Stock is gone, most nearly going with a 6 ARC.

105 & 108 factory 6 ARC is 2600-2660fps in my 18" AR. 3.1 mils and 850 ft-lb at my elevation (2000ft). Supersonic to 1200-1250yd.
 
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Want 80 / 85 / 90 gr bullet?
There are ways to get those bullet weights from "factory" ammo.

I wasn't looking for a like for like projo, just a heavy for caliber. In the ARC's case, that's a 105 in my opinion.

105 & 108 factory 6 ARC is 2600-2660fps in my 18" AR. 3.1 mils and 850 ft-lb at my elevation (2000ft). Supersonic to 1200-1250yd.

Epic. Over triple the energy. I can't think of a valid reason for a 6.8 anymore except for maybe SBR length barrels, and even then I'm not certain it's discernable.
 
You either need to send that ammo back to Hornady to be resized or you can do it yourself. The first two batches Hornady sent out were 2.245 to 2.250 OAL. The new spec for this ammo is 2.200. If you do not resize it the ammo will push into the lands.
I just checked, my Hornady black ammo lot #: 3201435 is loaded to 2.250 and it loads into the lands.
 
I was talking an 85 TSX in 6mm ARC
85 TSX @ 2800 from 6mm ARC would offer 1490 ft lb at muzzle, 469 ft lb at 500 yds, 64.3" drop, 31.8" of drift (10 mph, full value)
I'm pretty sure 2900 with 6mm, 85 TSX would be possible and the 6mm is 35% higher BC than the 6.8mm, 85 gr version.

105 Hornady BTHP @ 2550 offers 1523 ft lb at muzzle, 699 ft lb at 500 yds, 66.7" drop, 22.3" of drift.

Yep, there is a reason I like the heavier bullets for caliber.
 
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For the sake of discussion on velocity, I get 2900fps exactly using a Proof Carbon Barrel with 90g Gold Dots and factory ammo out of my 6.8. I'm 3.7mils to 500 yards and 264ftlbs of energy. Anyone have comparable data for their 6 ARC w/ 18" barrel at 500 yards? @MSTN

Once my 6.8 Stock is gone, most nearly going with a 6 ARC.

Not a direct comparison because mine's a 19" barrel and 243 LBC, but the 90gr TGK does 3050 fps, and the 90gr ELDx will do a little under 3,000.

At 500 yds that 90gr TGK needs 2.2 mils and delivers 825 ft-lb. The 105gr loads need a little more elevation but drift less in the wind and hit harder.
 
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85 TSX would make a wicked killing bullet for thermal hunting, hence my question.

I’m a bigger for caliber bullet kinda guy in general, there are exceptions to rule thought.

I’m still waiting for my Odin barrel (no ETA yet, frustrating) but am hoping that by the time I get it and build the rifle someone will be loading the Barnes TSX, TTSX or LRX bullets in 6ARC.

Damn, I might have to get back into reloading, but hate to take the plunge.
 
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Has anyone worked up a 6ARC load with VV N540?

I found a pound of it in my powder inventory and know its a good powder for 6.5G. Looking to try 30.0grs of the stuff with the 105gr Berger at 2.25". But if anyone has any intel, it would be appreciated.
 
Has anyone worked up a 6ARC load with VV N540?

I found a pound of it in my powder inventory and know its a good powder for 6.5G. Looking to try 30.0grs of the stuff with the 105gr Berger at 2.25". But if anyone has any intel, it would be appreciated.
Over 29 of N-540 and you'll most likely be over pressure based off what I've seen in a Bartlien bbl, 6mm AR and ARC is slightly less capacity.
 
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