Just to share a data point, I put together a 22 inch Rifle +2 gas Rainier Match Barrel AR and shot it last Saturday. 30 degrees out, Omega suppressor threaded on and 108 Hornady factory Match ran 2640fps and 106 TAP was 2639fps. Barrel is brand new. Going to be a hog and coyote hunting rig shooting from a tripod so I was using a REAP IR thermal. Barrel is heavy AF.
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New 6mm Advanced Rifle Cartridge
- Thread starter Gtscotty
- Start date
I try to get max velocity + accuracy at 600yds. When I was using Varget, I stripped the lug next to the extractor for the past 3 bolts when approaching or past 1000 rounds. I am now using either CFE223 or LeveRevolution and getting about the same velocity and accuracy. I used QuickLoad as one check on chamber pressure. Never checked headspace but the brass was fireformed from 6.5 Grendel brass.
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It's too early yet on both of my 6 ARCs to know how quickly the barrels will die, precision fade, etc. But so far, so good. My first build used a 22" Shaw barrel. I wanted a long range plinking toy that could be used to snipe varmints. It has shot great so far with somewhere around 400 down the tube. On a good day, I can get below .5 MOA 5 shot groups at a hundred yards (best so far is 0.38) and have gotten just over .5 at 700 yards. At 1000 yards, it beat a 20" target like a redheaded stepchild. Groups were running 8" on up.
My second build is shown in this thread. It's an obsessive compulsive ultralight build with a Proof CF barrel. We've only 60 rounds of factory Hornady ELDX through it so far. It often places 4 rounds tight with a flier to stretch the group to .75 to 2 MOA, but ELDX factory is kinda like that. This is meant to be a hunting and EOW gun. I'm expecting handloads to tighten it up but I always start with factory for the first ~140 or so rounds, because I want to shoot a new gun right now.
I'm not down on 5.56 NATO, but by comparison, I think this cartridge is the shit. I have the parts in hand to build another, but I'm too busy working and having fun to put it together. I've reloaded factory Hornady brass with good results through 4 firings and have been working up a bunch of Lapua 6.5 Grendel brass. The Lapua seems more temperamental, but that may be my process more than the brass. I'm mostly handloading 109 Bergers and 110 ATips with Lever, CFE223 and Varget.
The wind was variable, so it ranged 0.6-1.8 MIL by my notes. The 109 Bergers may be high BC for a 6mm, but they still get pushed around quite a bit. One windy day at 400, we were in the 1.4 range.
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Just saw this. Thought I should share. Peterson Brass will now be manufacturing 6 ARC brass starting sometime in Q2 of this year.
Black Hills is making 6 ARC now too, but its pricey as youd expect.
Well that's at least some positive news on 6ARC brass front. When I got my order of Starline grendel to convert a couple years ago, I threw it all on the floor and did brass angels. I've got a small pile of dirty cases to process currently.
It's been a weird year in terms of shooting. I've gotten in a decent amount of handgun practice but not much rifle. We've put a hundred or so rounds of factory ammo down the tube (see above for spec), mostly ELD-X and recently, ELD-M. The ELD-X ran around 1.1 to 1.5 MOA, 5 shot groups at 100, more often towards 1.5. The ELD-M has been typically running a bit over 1 MOA at 100 with the best groups in the .75 range. At 400, the ELD-Ms have been mostly 1.1-1.5.
With handloads, my other 6 ARC (22" Shaw barrel) is typically 0.4 to 0.6 MOA at 100, so I was thinking the Proof barrel on this lightweight gun was mediocre. Then, today, I pulled out some of the early target data shot with the Shaw gun shooting ELD-M's. It looked a lot like the Proof barrel gun. So I'll need to get off my lazy ass and work up a load for the Proof gun.
whats up guys, I am trying to get more questionable quality stuff on Rumble as opposed to YT. I just posted this video on how I process match brass (6ARC [converted starline] in the video). Feel free to post or roast. Just trying to help out the hive etc...
Rumble Video - Match Rifle Brass Preparation:
Rumble Link -
BrassBucket Link - https://brassbucket.net/2023/05/22/match-brass-processing-video-on-rumble/
The 6ARC got left in the trunk yesterday. I was confirming zero for 2 other bolt guns and long range and figured I would also bring the know working gun(6ARC) as a backup. Anyway - Have a great week!
Rumble Video - Match Rifle Brass Preparation:
Rumble Link -
BrassBucket Link - https://brassbucket.net/2023/05/22/match-brass-processing-video-on-rumble/
The 6ARC got left in the trunk yesterday. I was confirming zero for 2 other bolt guns and long range and figured I would also bring the know working gun(6ARC) as a backup. Anyway - Have a great week!
I'm building my first 6mm ARC, and hoping to set myself up for success by buying the correct parts the first time. I have a Rock Creek Craddock barrel in hand, it's 22" and +2 rifle. Will only be ran suppressed. I will run an adjustable gas block, and I'm semi-familiar with how to tune. I've read alot of this thread and searched, but couldn't find direct answers. Couple questions:
- What's a good/better adjustable gas block? Was looking at the AERO adjustable, I like that the screw is spring loaded with clicks, and doesn't need to be tightened down.
- For a suppressed 22" +2 barrel, what (Carbine) spring and buffer weight would be a good starting place, with the goals of increasing accuracy and lowering recoil? I know alot of folks run standard just fine, but lower recoil sounds great.
I second the SA gas block. But once I got it tuned to my load I don't adjust it. Then there are these:
RIFLESPEED Gas Controls for AR15 and AR10 Style Rifles
www.riflespeed.com
Has anyone fired Black Hills 103 ammo in a bolt gun? Curious how your velocity matched up against your barrel length.
The Riflespeed do look interesting.
I don’t want shit sticking out beyond my handguard personally. I also get it set and rarely have to make any adjustments after that. If so using an Allen key isn’t really a hassle at the range. It’s not something you need to be able to grab and twist on the go
I don’t want shit sticking out beyond my handguard personally. I also get it set and rarely have to make any adjustments after that. If so using an Allen key isn’t really a hassle at the range. It’s not something you need to be able to grab and twist on the go
I’ve been using the Aero gas block and so far so good. I only have about 140 rds on it though so I can’t speak for overall longevity.
I built with a 22 inch Rainier Match +2 gas, SLR gas block, Toolcraft standard weight Grendel BCG, A5 extension and standard a5 spring and buffer. Runs great with very little recoil. Just breaking it in but accuracy looks to be sub MOA with Factory 108 ELDM's.
Pictured with a Browe BCO just to get the feel of it. Currently wears a Reap IR2 35 Thermal. Whole thing is a heavy SOB but it's a tripod gun for Hogs and Coyotes and I won't carry it far.
Pictured with a Browe BCO just to get the feel of it. Currently wears a Reap IR2 35 Thermal. Whole thing is a heavy SOB but it's a tripod gun for Hogs and Coyotes and I won't carry it far.
I have the same barrel at +2. love it. You will to. Paul’s shop does it right.
I have SA. I don’t run suppressed, but will eventually. I migrated to the lighter Sprinco spring and lighter buffer weight, gas block tuned to bleed off most of the gas. I got mine a while back (fall ‘21 I think). The gas port is small (can’t recall what Paul said it is) on the assumption most folks would run suppressed. Had some issues tuning it/lock back, but eventually found the sweet spot with the lighter spring/weight. I didn’t want to open up the gas port thinking I would get a can.
I think you would probably be good to go with the standard spring and weight, with the AGB and can. Don’t know about the Aero AGB but their stuff has been good in my limited experience so hopefully that will work well for you.
Hope that is helpful. Good luck and keep us posted.
Update to my previous posts about the lug set back on the Rainier UM barrel. Rainier agreed the extension was soft.
Under 500 rounds. Below shows the contrast between the unused extractor lug vs. what all the others looked like @ +.013 head space.
Rainier replaced the barrel. The Maxim bolt went in the trash. I picked up a Sharps Low Mas BCG with the new Sharps Grendel type 2 bolt as a replacement. I'm curious to see how the DLC'd S7 Tool Steel bolt holds up.
I've got a Rifle Speed GB on a 16" Reece & digging it. Fit was good, takes up very little space in rail, & adjustments responsive. $$$ not cheap though.
For 6 ARC I see there do now offer .875 option, but currently out of stock. The Rifle Speed needs a straight gas tube & they offer them up to + 1" only.
Under 500 rounds. Below shows the contrast between the unused extractor lug vs. what all the others looked like @ +.013 head space.
Rainier replaced the barrel. The Maxim bolt went in the trash. I picked up a Sharps Low Mas BCG with the new Sharps Grendel type 2 bolt as a replacement. I'm curious to see how the DLC'd S7 Tool Steel bolt holds up.
I've got a Rifle Speed GB on a 16" Reece & digging it. Fit was good, takes up very little space in rail, & adjustments responsive. $$$ not cheap though.
For 6 ARC I see there do now offer .875 option, but currently out of stock. The Rifle Speed needs a straight gas tube & they offer them up to + 1" only.
The .875” RifleSpeed blocks haven’t hit the market yet. You can pick up straight +2 from White Oak, off the shelf.
I've been running 6 ARC for a couple years now, 22" Premium series .875 Ballistic Advantage at first with a rifle legnth gas. Recently moved on to a 25" McGowen 7 twist .875 +2 gas. Both builds I've used the SA .875 gas block and they've worked like a charm. I have an H2 buffer with a Spingco blue med hvy spring on the 22" and it runs perfect but the same setup for the +2 wouldn't cycle or hold the bolt open. I changed my +2 to a JP Silent Capture Spring setup, standard buffer weight with the black spring and all is well. In other word lighter buffer and lighter spring. The McGowen runs smooth as silk now. Definitely recommend SA gas block and the JP SCS with the spring pack. I just wanted to head to the range one time to get my gun running good so I spent s few extra bucks on the spring builder with the extra springs. As a side note the .875 block is a super tight fit with a standard handguard. I went with the Aero Precision 16.5 " Enhanced handguard which is quite roomy to cover the +2 gas block. A +2 will stick out past a 15" setup. https://www.aeroprecisionusa.com/ar15-enhanced-mlok-handguards
GEN 2 AR-15 Silent Captured Spring Builder with Alternative Spring P
FWIW, I'd suggest you query Craddock on what buffer/spring combination he would recommend to use with his product. I'm sure he has sufficient data feedback to provide some solid recommendations. Keep in mind, he knows the port size so he knows what would work the best, suppressed and unsuppressed.
As for the AGB, I'm partial to the SLR Sentry series, having used them for over a decade and experiencing zero issues. Like any AGB, once you adjust it for a particular ammo/load it is unlikely you need to change the setting unless you change the ammo/load or switch between suppressed or unsuppressed. I have found in multiple builds/multiple calibers, that using the AGB I have never had to change my buffer system from the MILSTD buffer/spring/buffer tube. The AGB allows for adjusting the gas flow allowed into the tube that controls the cycling, negating in majority of cases, the need to change buffering components. YMMV.
I disagree with most of the other input you've gotten. If you're shooting 100% suppressed, there's no good reason to use a click-adjustable gas block. It won't hurt anything, but it's wasted money for no value; you'll leave it set in one position after getting it adjusted, and it'll freeze up with carbon and function exactly like a quality set screw gas block. (And I definitely wouldn't get a SA; that bleed off thing is stupid).
The $60 Seekins set-screw gas block is quality and will do exactly what you need. (I reference the price because they have a different one for about double that, which is for switching between suppressed and open, not what you need.) I've used a bunch of them and they've been great.
If you're looking for lower recoil, the standard carbine spring & buffer is lower recoil with proper gas adjustment, compared to the heavy buffer setups a lot of people here run. Lower reciprocating mass translates to less reticle movement if you're spotting hits or shooting rapidly. A few of mine even use reduced weight buffers and light weight bolt carriers, and track very flat in recoil. Gas tuning is key for this of course, but you're already talking about tuning the gas; you don't need to also use a heavier buffer.
I've also had great performance from the $60 Seekins on a build with a 22" Shaw barrel. On my newest build (18" Proof) I used the JP low profile 2-piece in order to have it not touch the handguard. It was a bit finicky initially, but once set up right it's been solid. This one has the Geisselle Super 42 braided buffer spring and their standard rifle buffer.
I have 5 or 6 SA AGB and only had one “freeze up” with carbon. It didn’t take more than hand torque with their supplied Allen wrench to break it free. I shoot 98% suppressed. I agree the Seekins low profile non-adjustable are a great piece for the money. I could likely get by with that but I’d rather spend $30 more and have the option to tune.
Just incase folks didn't see it, Starline is now selling dedicated 6mm ARC brass.... well at least its listed now. From what I can gather it sold out in about 10 minutes, and the back orders were stopped after 30 minutes. But at least its now in their rotation.
Edit 6-27-23 10:09am pst, starline has the backorder option back up.
case of:
250 = $159.00
500 = $303.00
1000 = $576.00
I'm a little disappointed in the price but its still cheaper than the little box's from hornady.
Edit 6-27-23 10:09am pst, starline has the backorder option back up.
case of:
250 = $159.00
500 = $303.00
1000 = $576.00
I'm a little disappointed in the price but its still cheaper than the little box's from hornady.
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Thanks for the notice.
I tried to order a cool K. we will see if it goes through. I got a order complete screen. I still have piles of processed/converted Grendel brass ready to prime but I just couldn't resist adding this to the starline headstamp collection...
I won't waste a Small Rifle Primer on anything else currently. Well maybe some 9mmMAJ ammo...
I tried to order a cool K. we will see if it goes through. I got a order complete screen. I still have piles of processed/converted Grendel brass ready to prime but I just couldn't resist adding this to the starline headstamp collection...
I won't waste a Small Rifle Primer on anything else currently. Well maybe some 9mmMAJ ammo...
Well if it makes you feel any better I back ordered 1k 300blk and 2k 30-06 on june 10th from starline. The 300blk showed up on the 21st, and no word on the 30-06. Last year I ordered 1k .44mag and that took about 4 weeks to show up so I'm not worried. If it takes longer than 2 months I'd probably pick up the phone just to check on it.
Definitely small primer.
It says it in the title of the ordering page.
Its available for backorder again from starline! So I snagged 1k pieces this time as I missed out last time. Now I just need to decide on a barrel....
Looks like HSM is loading the 6 ARC as well. 75 gr Vmax, 95 gr SST, and 95 gr VLD. I picked up 5 boxes of the 75 gr Vmax and was happy to see it's loaded in Starline cases.
A friend of mine said he’s getting pressure signs in starline brass at much lower speeds and charge weights than Hornady. Anyone else seen the same?
I’ve only loaded with converted Hornady grendel cases so far.
I’ve only loaded with converted Hornady grendel cases so far.
Lots of info missing here. Bolt gun or gas gun, barrel length, what powder, charges, and resulting velocities?
And what does he mean by pressure signs?
In a 6 ARC gas gun, by the time you start seeing what we typically think of as pressure signs in rifle cartridges you're well over 52k psi and are on your way to breaking lugs.
Measuring the case volume of some Starline cases relative to Hornady would be much more helpful, and if that's lower (and it likely is), then loads developed for Hornady cases would need to be reduced to achieve the same operating pressure.
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This makes me happy to see. Now we can shoot "factory ammo" to satisfy the MOA guarantee of barrel producers and be left with starline brass. The only down side I see is they don't offer anything in 105-108gr range.
Has anyone tried any of the Vihtavuori N1xx powders yet to solve the temp stability vs velocity dilemma?
I use the N1xx series for a number of cartridges (N140 w/77gr 5.56mm, N150 w/175SMK .308WIN, N160 w/95VLD 6mmC).
I tried and tried to get a decent load with N140 out of the 6ARC, with both 95VLDs and 110 A-Tips, but it just couldn't compete with LVR, from my experience. The N1xx are excellent in semi-autos because of the reduced heat and shoot so much cleaner than LVR, but 6ARC seems picky. I also struggled a bit with Varget and ARComp; neither gave me the consistency and velocity of LVR.
I tried and tried to get a decent load with N140 out of the 6ARC, with both 95VLDs and 110 A-Tips, but it just couldn't compete with LVR, from my experience. The N1xx are excellent in semi-autos because of the reduced heat and shoot so much cleaner than LVR, but 6ARC seems picky. I also struggled a bit with Varget and ARComp; neither gave me the consistency and velocity of LVR.
I've been playing with Staball Match a bit with 108gr, 105gr and 90gr in the ARc, and it's not quite as fast as LVR/CFE/2520, but I'm pretty happy with the velocity and accuracy so far, seems like a pretty good fit.
I've been looking in the Vihtavuori load data section specifically 6 PPC and 6BR. N540 is recommended for the 6BR. The 6BR is very similar to the 6 ARC. Might be worth a try...
That said the load data gives a 52000 CUP max for the 6 BR. It will drive a 105 gr bullet at 2776 fps (maxload), which is very close to what I get with Hornady factory ammo, also at 52000. I get ~2750 using a 26 inch barrel (bolt action) with the 108gr Hornady bullet.
www.vihtavuori.com
www.vihtavuori.com
That said the load data gives a 52000 CUP max for the 6 BR. It will drive a 105 gr bullet at 2776 fps (maxload), which is very close to what I get with Hornady factory ammo, also at 52000. I get ~2750 using a 26 inch barrel (bolt action) with the 108gr Hornady bullet.
N540 high energy powder - Vihtavuori
Vihtavuori N540 is an excellent choice for cartridges running from the .223/5.56mm, .308 Win. and .30-06 Springfield with appropriate bullet weights. This is also a great powder for 6,5x47 Lapua and 6.5 Creedmoor as well as the .223 when using heavy bullets. Exceptionally clean-burning and...
www.vihtavuori.com
Rifle reloading data | Handloading | Rifle calibers | Centerfire Rifle bullets | Reload your own ammo - Vihtavuori
Vihtavuori offers rifle reloading data for numerous calibers and bullets for match and hunting purposes. Never exceed maximum loads.
www.vihtavuori.com
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I've been looking in the Vihtavuori load data section specifically 6 PPC and 6BR. N540 is recommended for the 6BR. The 6BR is very similar to the 6 ARC. Might be worth a try...
That said the load data gives a 52000 CUP max for the 6 BR. It will drive a 105 gr bullet at 2776 fps (maxload), which is very close to what I get with Hornady factory ammo, also at 52000. I get ~2750 using a 26 inch barrel (bolt action) with the 108gr Hornady bullet.
N540 high energy powder - Vihtavuori
Vihtavuori N540 is an excellent choice for cartridges running from the .223/5.56mm, .308 Win. and .30-06 Springfield with appropriate bullet weights. This is also a great powder for 6,5x47 Lapua and 6.5 Creedmoor as well as the .223 when using heavy bullets. Exceptionally clean-burning and...
Rifle reloading data | Handloading | Rifle calibers | Centerfire Rifle bullets | Reload your own ammo - Vihtavuori
Vihtavuori offers rifle reloading data for numerous calibers and bullets for match and hunting purposes. Never exceed maximum loads.
What’s the difference in case capacity between a Lapua 6mm BR case and a Hornady 6mm ARC case?
I don't know exactly but it is 1 grain or less, probably less. The BR has a longer neck than the 6 ARC = less powder. That's why wildcatters came up with the 6 BRA with a 40 degree shoulder. More powder.
This is true, more info needed. That said, I've seen large pressure spikes myself, including hard extraction and one blown primer with factory ammo on my bolt gun.
It took a while but I was able to trace it. My bolt gun has a tight chamber, which makes me believe that this could be common in the 6 ARC. It's a high performance cartridge for its size and was designed that way.
In my case the cause was that any little bit of oil or cleaning fluids left in the chamber caused the spikes. It doesn't take much at all. I now mop my chamber with 91 percent alcohol when I'm done with cleaning. No issues after that.
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