New 6mm Advanced Rifle Cartridge

[newageroman]

I'm sure you will not be disappointed with either. I debated about opening my CFE 223 for some more load dev but decided to trade it to a friend to help him out and I'm sticking with LL. I just have more load dev with LL and its more available.
-post groups when you get em!

 

[fifdynutz]

Finally got a chance to go crack off one of each load I have in my 2 arc rifles. One is a 14.5 faxon heavy barrel pistol, the other is a 16" faxon gunner match barrel.

The loads are:
Box hornady black-
29.5g imr 4895, 72g Barnes varminator-
33g lever, 72g Barnes varminator-
30.2g lever, 90g sierra tgk-
28.4g CFE, 103g eld-x-
30.2g CFE, 90g eld-x

 

[Dino11]

Using CFE223 and Lever to see which my rifle (I have a few) likes best.

A friend swears by 29.5grs of Lever' at 2600fps+ with a 105 Hornady HPBT at 2.310" COAL, Lapua brass and CCI 400s as his general purpose (targets and deer hunting) load, which will fit in an ASC mag (just barely).

Be careful loading that bullet to 2.310, that's the bullet that Hornady had to recall loaded to 2.260 because it was getting stuck in the lands. Now you can load a Nosler or Berger to that length, but not the Hornady.

 

[david walter]

Yeah. My rifles won’t take over 2.285 with the 105 BTHP, even if the magazine allows it. And I like 29 grains of CFE223 and CCI 450s for that load.
One barrel is a 20” Pacific Research stainless, the other a 18” Wilson Combat fluted Predator.

 

[thelaststraw]

Quick question about gas length for a longer barrel. If I was to get a 24" barrel spun up would rifle plus 2 (or even 3?) Be beneficial. I primarily shoot suppressed, meaning I don't intend to ever take the can off. I'm not worried about portability as far as hunting or anything like that. I asked on another forum, 6ARC specific, but no response yet traffic there is slow at times.

 

[godofthunder]

Quick question about gas length for a longer barrel. If I was to get a 24" barrel spun up would rifle plus 2 (or even 3?) Be beneficial. I primarily shoot suppressed, meaning I don't intend to ever take the can off. I'm not worried about portability as far as hunting or anything like that. I asked on another forum, 6ARC specific, but no response yet traffic there is slow at times.

I'm guessing you'd be fine with a +2. If I was doing that I'd probably stick to rifle length, have the gas port made small and adjust until it was where I wanted it. Or just roll with an adjustable gas block.

 

[thelaststraw]

I'm guessing you'd be fine with a +2. If I was doing that I'd probably stick to rifle length, have the gas port made small and adjust until it was where I wanted it. Or just roll with an adjustable gas block.

I have a 20" rifle length currently and have to damn near fully bleed the gas when suppressed. I was trying to wrap my head around the whole dwell time and bolt unlocking optimally or not, etc. Seems like going 4" longer would be quite a bit more duration for the gas in the barrel and the rest of the system. What is the purpose of going longer then? Most all the blanks from 20" up are at least plus 2 from the places I've been looking.

 

[Ledzep]

I have a 24" barrel that is Rifle+1 and it functions fine without a suppressor. Any time you run suppressed you should run some sort of adjustable gas because I've never had a rifle that is tuned well suppressed run reliably unsuppressed.

 

[thelaststraw]

I have a 24" barrel that is Rifle+1 and it functions fine without a suppressor. Any time you run suppressed you should run some sort of adjustable gas because I've never had a rifle that is tuned well suppressed run reliably unsuppressed.

I have a superlative arms gas block and have it dialed in pretty good. It's definitely noticable if I forget to adjust if I take the suppressor off, which only happens to store or Chrono a load each way. I finally found a bullet it likes and am working on a load and seating depth.

I wasn't sure if there is a certain point where going longer gas is necessary if at all. Thank you sir.

 

[Dino11]

I have n 18" barrel that has a +2 rifle gas system on it. It has a rifle buffer system with rifle buffer and spring. I had to lighten the buffer by switching four of the steel weights to aluminum weights, it lightened the buffer from 5.4 oz to 3.6 oz. I also had to run a reduced power rifle spring, and those suckers are hard to find. It is 10% reduced power, it is a very soft shooting rifle, almost like shooting a .22. Looking through the scope the rifle never leaves the target, you can see the holes being printed on the target. Brass almost rolls out of the ejection port and falls about two feet from the rifle. You might get lucky using a carbine buffer system not haveing to do any modifications to the rifle, but you will need an adjustable gas block for sure.

 

[thelaststraw]

I'm running a carbine buffer and spring with the rifle length 20". I'm thinking plus 2 on a 24" and an SA adjustable gas block. I don't think there is much to be gained after 24"....perhaps even 22" but I don't know for sure. A little more speed for 105-108s and a soft shooter like yours is what I'm after. Thank you.

 

[Dino11]

You will also need a good muzzle brake, I run the Odin Works brake on all my 6 ARC's. It just works well, and when I find something that works I stick with it. I was on my own figuring out my rifle. The barrel is an Odin works,spun from a McGowan blank. The gas port on it is .101, that's pretty big but it needs to be larger because of the +2". Although my gas block is only one rotation from being fully closed. It will operate with a standard rifle spring but it was way softer using the reduced power spring and turning the gas way down

I was having all sorts of problems in the beginning, failure to feed and eject, trying to feed two rounds at once, swipe marks on the brass, having to deal with Hornady's bull shit Black ammo that eventually got recalled. I worked with Hornady's engineers on that deal. And the fact that Odin had done absolutely no testing with a rifle buffer system on their rifle length gas system. They only tested it with carbine buffer so no help from them on that issue. I will state that I got lucky, the first modifications I did worked and after dialing in the gas block I have one sweet sub MOA rifle.

 

[thelaststraw]

If it's plus 2 on an 19" that leaves 2.5-3" after the port? Wouldn't plus 2 leave almost twice that on a 24"? I very well could be wrong but isn't the lengths standardized regardless of barrel length? So with a plus 2 24" and a .101 port there would be much longer dwell time for gas to do it's work....maybe? I'm trying to understand this stuff better.
I appreciate your help. Currently I shoot suppressed since brakes rattle the crap out of my brain.

 

[Dino11]

The longer dwell time is the whole concept behind the plus gas system. And yes you will have more barrel after the gas port on a 22" or 24", the system is standardized. One of the bigest advantage of longer dwell I believe is more accuracy, and you pick up a little more speed because the bolt stays locked longer and the bleed off from the gas port is further down the barrel thus the gasses are pushing the bullet for a longer period of time before it bleeds off. My 18" barrel gives me 20" velocities, at least matches my 20" barreled gun with the same ammo.

 

[thelaststraw]

Thank you again. That helps more than you will ever know. There is so much misinformation out there about this stuff. It makes things hard on someone like me to sort through facts and opinions.

 

[TonyTheTiger]

The longer dwell time is the whole concept behind the plus gas system. And yes you will have more barrel after the gas port on a 22" or 24", the system is standardized. One of the bigest advantage of longer dwell I believe is more accuracy, and you pick up a little more speed because the bolt stays locked longer and the bleed off from the gas port is further down the barrel thus the gasses are pushing the bullet for a longer period of time before it bleeds off. My 18" barrel gives me 20" velocities, at least matches my 20" barreled gun with the same ammo.

Most of this is incorrect.

 

[thelaststraw]

Well crap...lol

The plus gas shortens the dwell time?

 

[TonyTheTiger]

Well crap...lol

The plus gas shortens the dwell time?

Yes. And if you chrono with gas on vs. gas off you'll know that none of this has anything to do with velocity.

 

[thelaststraw]

Ahhh, I'm not after velocity or even softer recoil at the expense of reliability. The length will give the speed and recoil wise...it's 6ARC so it's already pretty soft. But going from 20" to 24" my gut tells me +2 would be beneficial as it's predominantly suppressed. I use SA gas blocks and carbine/carbine buffer with extra weights if needed for whatever reason.

 

[Dino11]

Most of this is incorrect.

Not what the barrel maker explained to me, please elaborate. If the gas port is further down the barrel the gas will take longer to unlock the bolt. At least that is what I was told.

 

[david walter]

Just because Tony the Tiger said it, doesn’t make it Grrrrate!

sorry, I had to….

 

[r.tenorio671]

...FWIW, IIRC the original Stoner design for the M16/AR-15 used a 20" barrel with a rifle length gas system and designed to function reliably with ammo operating at the ~52K PSI range. 6ARC gas gun ammo is designed around that same PSI level....

 

[TonyTheTiger]

Not what the barrel maker explained to me, please elaborate. If the gas port is further down the barrel the gas will take longer to unlock the bolt.

That part is correct, that and lower pressures in the gas system which can be necessary to get a high pressure large frame cartridge (6-6.5CM) timed correctly. In a small frame it's pretty much never necessary, it just has benefits like lower recoil and nicer on brass, especially when suppressed, at the expense of a narrower operating window, especially when unsuppressed.
The longer gas system shortens dwell time, that is the time after the bullet has passed the port but before exiting the muzzle.
Drilling a gas port has a negligible effect on MV. You can easily test this theory. Moving the gas port 2" has an ultra negligible effect on MV.
Gas port location has zero to do with accuracy.

Using Odin as a reference actually hurts your argument more than it helps. Everyone that knows anything scratched their heads when they released the 18" +2" barrels, and consequently no one was surprised that they didn't work great. You said yourself that they barely tested them.

 

[Gtscotty]

The +2 gas system works quite well with my 21" Odin, which is run suppressed all the time. I have the gas turned pretty low as well, runs very smoothly with a can, but I have to turn it up some when I take the can off, as expected.

 

[Triple D]

Using Odin as a reference actually hurts your argument more than it helps. Everyone that knows anything scratched their heads when they released the 18" +2" barrels, and consequently no one was surprised that they didn't work great. You said yourself that they barely tested them.

Yup. Made Zero sense unless you were trying to create a finicky headache.

 

[ormandj]

FWIW I am running a rifle+1” on my 18” and a carbine+1” on my 10.5” and they run great suppressed or unsuppressed with H2 buffer weight equivalent on a carbine length stock.

I do have an adjustable gas block on these two to dial things in (setting up another two rifles with the same barrel setups with fixed gas blocks and Bootleg BCGs right now to test), but they ran great unsuppressed without.

I wouldn’t go rifle+2” on an 18” barrel. With the correct gas port size it would be fine on a 24” barrel. You also start to get diminishing returns, and can encounter finicky behavior, so even if you’re running longer barrels I wouldn’t extend the gas tube beyond that.

 

[Dino11]

Finicky it was, but after getting it figured out it has run flawless. And yes the gas port is almost to the end of the barrel. And the gun is very easy on brass and has virtually zero recoil impulse.

I see what your saying about dwell, I was mixing up dwell and lock up time.

 

[thelaststraw]

The +2 gas system works quite well with my 21" Odin, which is run suppressed all the time. I have the gas turned pretty low as well, runs very smoothly with a can, but I have to turn it up some when I take the can off, as expected.

Good deal, that's good to know. I was looking at a 22" ultra match but for a little waiting I could get a custom from a couple different places. 22-24" is about all I'd want on a small frame gas gun but wasn't sure all the details on gas lengths. I run suppressed all the time but can tune gas block as needed. My 20" isn't bad but it's a light/med contour and gets warm fast.

 

[david walter]

Hunting deer purposes, 95 BT or 103 ELD-X or 105 BTHP or 107 SMK?

 

[trdjohn]

I'm curious about all those too and 90 gr hornady eldx

 

[trdjohn]

Woohoo! Just got call that my McGowan 6 mm ARC barrel is finished and will ship out. I paid off the balance right away. Savage varmint contour, 1:7.5 twist, 26" and barrel nut. Have all the other parts, was just waiting on the barrel. Ordered back on May 3rd, they had 12 to 16 week back log, so just right in the middle of that estimate.

 

[ormandj]

Hunting deer purposes, 95 BT or 103 ELD-X or 105 BTHP or 107 SMK?

Out of those I'd run the ELD-X, but the ideal choice would depend on the type of deer, foliage cover, range, etc. The ELD-X will work well in most situations.

 

[thelaststraw]

Woohoo! Just got call that my McGowan 6 mm ARC barrel is finished and will ship out. I paid off the balance right away. Savage varmint contour, 1:7.5 twist, 26" and barrel nut. Have all the other parts, was just waiting on the barrel. Ordered back on May 3rd, they had 12 to 16 week back log, so just right in the middle of that estimate.

I was trying to decide who to go with and CLE were the first I got to talk to so went with them. They were very helpful and I have a 24" stick coming my way at some point.

 

[trdjohn]

I was trying to decide who to go with and CLE were the first I got to talk to so went with them. They were very helpful and I have a 24" stick coming my way at some point.

the McGowan on the way is for a savage bolt action receiver, I've already got an odin 18" in a gas gun

 

[lennyo3034]

Shot a regional match with my AR in 6ARC today. Factory 108s. Very impressed with the performance out to 1000 and it held its own against the bolt guns. Top 5 overall and most of my dropped shots were because the heat got to me and I had shit for brains. Same can be said for the other shooters though.

 

[newageroman]

Man, that's awesome - Way to hold with the bolts! I didn't fare so well today in the local 600 match. May have been my ammo/wind. I thought I grabbed my match ammo and it happened to be the slower BTs that may not have had the best vel. consistency - just plinking ammo.
I got to anneal 250 cases and some 6.5CM too.

After the match, everybody left and the wind died. I shot the 1250 plate on my 6.5CM with the new Ivey base and Sightron 10x50 - heaven for me!!! got to test a cool 22 too.

I need to make a better bag system, and I have one in mind. I also will probably off that stock and put one on that will slide on the rear bag better.

 

[A&8's]

Shot a regional match with my AR in 6ARC today. Factory 108s. Very impressed with the performance out to 1000 and it held its own against the bolt guns. Top 5 overall and most of my dropped shots were because the heat got to me and I had shit for brains. Same can be said for the other shooters though.

My new ARC will shoot her 1st match this weekend. Just a local match, out to 900-ish. Last night, after shooting a bolt gun match all weekend, I went down to the reloading room and processed (annealed, sized and trimmed) 500 pieces of new Starline 6.5 Grendel into 6ARC. Load development starts tonight. I broke the barrel in last week with 7 boxes of factory 108's, so she should have already sped up. Hopefully load development goes quickly. Planning on either Hornady 105 BTHP or 105 Hybrids. Hopefully I can get the BTHP's to shoot well, as the hybrids I'd prefer to keep for bolt gun matches.

 

[thelaststraw]

I'm debating whether I should wait for my CLE barrel or get out to a 'local' match sooner rather than later. Local matches for me are a couple hours away. I'm also hoping the Hornady 105s will perform, although I'm the loose screw still. Definitely update in how things go, I have no idea where my equipment stands as far as capability for PRS type stuff and get all my info here really. From what I've seen myself and heard, it's a pretty capable cartridge for the small frame platform.

 

[newageroman]

Any Rear Bag Rider Stock suggestions? I got this stock for another lightweight build but looking for more of a DMR rider style. Still want to keep somewhat portable. I would fill the bottom pick rail with a slide, but there is no cheek riser on this one.

 

[godofthunder]

I'm considering dropping and XLR TR-2 on mine. If you do that, I have a free design for a bag rider for those.

XLR Bag Rider STL File

Free STL file for a bag rider that works with XLR TR2 stocks! You will also need two #10-32 x 1inch socket head cap screws. We recommend printing with our logo facing up and 4-5 perimeters for best strength.

rustynutsdesigns.com

 

[thelaststraw]

I've got a tr-2 and love it. For some reason on my rifle I need the riser pretty much bottomed out even with a 2" riser on my optic. At least I have the option to raise it if needed.
Does a bag rider help a lot with it? It seems pretty easy to pinch it together with the bag without it. My eneducated self figured it would get in the way more than help.

 

[newageroman]

Thanks for the options on stocks. I will look into them.
In other new Precision Reloading has a lot of Berger 105 bullet styles in stock, I just grabbed 500 105 VLD targets. I had been holding out for another big box of bergers, finally happened... they have 100 counts in stock too.

 

[thelaststraw]

Thanks for the options on stocks. I will look into them.
In other new Precision Reloading has a lot of Berger 105 bullet styles in stock, I just grabbed 500 105 VLD targets. I had been holding out for another big box of bergers, finally happened... they have 100 counts in stock too.

SCORE! Thanks for the tip. I'm psyched to try the Bergers.Ive heard nothing but good things about their consistency.

 

[newageroman]

Glad to help my ARC spinners. What powders do you have to use? Did you get the HTs, VLDs or BTTs?

 

[thelaststraw]

vLDs...I have a pretty good stock of Lever and a little H4895. Been pretty happy with the LVR so far since it doesn't really get effected too badly with the temps in Louisiana yet. Come winter, I don't know yet. Hopefully I come across some more temp stable powder if the results aren't so hot.
I'm not too concerned really as long as it's safe and consistent.

 

[trdjohn]

Put together a 6mm ARC bolt rifle. I have Savage 110 Desert Tactical in 6.5 CM, used that as the basis for the ARC rifle. Ordered McGowan barrel in early May and got the barrel mid August. It’s Savage Tactical contour, 26” target crown, and weighs about 4 lb 13 oz. I used a Northland shooters barrel nut and recoil lug. I bought both PTG and Savage PPC bolt head, and the OEM 223 front bolt baffle. Wound up using the PTG bolt head w/ front baffle. Have upgraded extractor kit w/ large detent ball and upgraded ejector. Used PTG Go/No-Go gauges. Bought a MDT 6mm BR magazine. Had MDT LSS chassis for Savage laying around, and Magpul PRS stock.

Used Viper barrel vise and NSS action wrench, factory barrel wasn’t too difficult to get off. New barrel went on nicely, headspacing was a breeze. After about 60 rounds, no issues at all feeding those rounds from the MDT mag to the chamber. However, even with the upgraded extractor, there is a 50/50 chance of the extractor pulling the case out of chamber. Doesn’t matter if I run it hard or soft.

First trip was 15 to 20 rounds of factory 108 ELD and 105 BTHP Black ammo, nothing to write home about. Got home, noticed loose nuts/bolts on stock, and the bolt action screw needed tightening. Tightened them up, cleaned the barrel. Barrel was super easy to clean with Wipe Out cleaner, minimal copper fouling.

Next trip out was pretty good. Shooting hand loaded 108 gr ELD Match (these were seconds bought from midway earlier this year - I sorted them by ogive length) Randomly chose 30.2 grains of Lever from Hornady manual for bolt guns, seated them 20 thou off the lands. Manual calls for 2750 fps from 24” barrel; over 15 shots I averaged 2,840 fps in my 26” barrel using Lab Radar. (Factory 108 gr Match ammo for six shots in my 26” barrel averaged 2,784 fps - but factory ammo is loaded for gas guns.) The hand load groups were from 1.00” to 0.5” @ 100 yds. I’ll readily admit I’m not the most consistent shooter. I used an Atlas cal bipod and rear bag. It was overcast and upper 60s, low 70s.

When I ordered the barrel I seated dummy rounds with 108 Hornady ELDMs with boattail junction at the shoulder/neck junction, they throated it to fit those. Even with the 108 eld bullet shoved into the lands, they easily fit the MDT mag. I also have a bunch of Berger 108 BT target bullets that I’m going to load up next, to see how they shoot. Those cartridge base to ogive lengths are similar to the 108 ELDMs.

Once I get a piece of real estate sold, I’m going to splurge a little on Bighorn Origin or TL3 action and move the barrel over to that and get MDT LSS-XL and their stock (not a huge fan of PRS stock) or maybe ACC chassis.

 

[Cajuntransplant]

Starting the process to get a 6ARC upper built up and I’ll be using it for 1 and maybe 2 day PRS matches and have 2 questions (after all 44 pages - lots of awesome information).

1- has anyone done load testing with H4895 or Benchmark with 103 - 108 weight bullets in AR platform (wanting temp stability to handle South Dakota summer as well as winter temp changes)

2- choosing between a 20” +1 from Proof or the 22” +2 from Rainier Arms which way would you go? It’s going to be a match rifle and probably 90% of the time just have a muzzle brake and not a suppressor.

 

[eddie102870]

son has a 22 in that showed up today will have some results in a week, hes waiting on a +2 gas tube to show up. i run a 18 in proof barrel and love it

 

[Cajuntransplant]

son has a 22 in that showed up today will have some results in a week, hes waiting on a +2 gas tube to show up. i run a 18 in proof barrel and love it

Nice!!! If you could, Post up any info you get once his is finished. Would love to get some of the numbers for velocities with it in here to reference.

 

[eddie102870]

Nice!!! If you could, Post up any info you get once his is finished. Would love to get some of the numbers for velocities with it in here to reference.

will do. hes on a short timeline to get it ready for a match the 1st of october so we should have some info shortly