6mm ARC Bolt Gun Loadings

67rschev · Feb 1, 2023

I have finished a 6mm ARC bolt action, and there's not a whole lot of data out. . Been fooling with the 6 arc in first a 18 inch and then a 22 in semi for the last year, so I have some baseline and experience with loading the cartridge. Did a shake down was with 10 rounds factory 108 eldm, and then a first ladder that started with Varget and the ( GAP ) Hornady 109 ELDM. Ran the ladder from 26 to 28, with depth at .020 of the lands. Liking what I am seeing, but worried I may be a bit over pressure. Hornady lists 28.1 to be max with the 108 eldm, I'm at 28. Sure seems the loads listed through Hornady seem to be much higher than other loading resources, such as Hodgdon. Ran it through GRT, and the program estimates 65 k using the 110 Atip ( modified in weight ) as the projectile. Brass looks perfect, but this is my first experience with the Nucleus receiver having no plunger ejector. Also, primers look slightly dimples in from pin strike. GRT estimates 26 inch barrel at 2822 fps and i was at ~2750, which would be about perfect.

Any one any experience with said combo or close, or could run this through Quickload if they have the time. Thanks in advance

skyrep · Feb 1, 2023

I started with the Bolt version first and now going to the Semi Auto route. In my Bolt gun: 24" Shaw 416R SS with 1-7 twist barrel. I found using H4895 for the 108 ELDM. Start at 26.6 and work up. Found a load (2770 fps with SD: 2.4) I found that H4895 for the heavier bullets worked better. Was not happy with Varget for the heavier bullets. Same results for the A-Tips.

67rschev · Feb 3, 2023

Thanks for the input, opposite paths ending in the same place. I've used the IMR 4895 in the past but not H. Also on hand, and in the mix I plan on working with RE15, Shootersworld Precision, and Leverevolution. Lever's been pretty good in the semi, just not a big fan of ball powder.

Here is the referred first work up with Varget, as stated it showed good promise. Watching them form as I was shooting, It felt like they were tightening up again at that 28 mark, maybe a little higher. Side note, brass and primer pockets were GTG at 28. Still nervous after running it through GRT

67rschev · Feb 6, 2023

Worked up some loads checking out the 27 grain window, results were pretty favorable. Tried a couple groups neck sizing only top row, and second sets with a light FL and .002 shoulder bump middle row, and a set with .005 bump. Seems as if it liked a little shoulder set back. Going to tweak the neck tension a bit and then go after the 28 grain area, thinking it could be near as accurate. May swap around some primers, dunno which would be best for the combo. Been using CCI 400s, and have all the others to try. Any one see any appreciable gains from one primer to the next with this cartridge ?

67rschev · Feb 15, 2023

Ran a couple more ladders yesterday, the first was with Varget and 108 Bergers and the second was with 108 elds and RL15. Things of note, the barrel picked up on average ~50 to 60 fps after a thorough cleaning at the 75 round mark. I pulled a couple patches during the first 10 rounds of barrel break in, but this was like a light switch instant 50 fps. Varget is showing more / comparable speed at roughly half a grain less than the Reloader 15. Somewhat confirmed earlier ladder showing 27 and 28 grains having nice accuracy windows. A big mistake at 28.5 of RL15, the last shot of the ladder was a full 120fps off the rest. Must of pootched something with the powder in the reloading block.

Varget and Berger 108s

RE15 and 108 ELDs

67rschev · Feb 21, 2023

Loaded up a two sets of ten revisiting the previous post's Berger / Varget combo at 27.9, and a tenth over at 28. Printed some nice groups, both charge weights showing same POI, I'll call this GTG. Think I'm at my practical limit with a bipod and bag anyways. Going to continue working on the 109 eldms next. I think the barrel has now stopped speeding up, at round count ~120

FuhQ · Apr 22, 2023

Midway came through for me, and the new (proper size) bushing showed up today. Got them all resized (again), and loaded up my first round of load development for my 16" Christensen Arms MPR. I'm running 1x fired and FL sized Hornady brass, CFE-223, CCI 400's, and Nosler 115 RDF's. I'm running all the way up to 29.0gr in 0.5 grain increments (first round of data is pressure baseline and finding a rough node pattern). I'll report back my findings.

In case someone else reads this in the future, DO NOT use bolt-gun load data in a gas gun. Bolt guns can handle a lot more pressure.

67rschev · May 2, 2023

UPDATE Unfortunately, the 28.9 Varget load with the Berger 108s sped up on me considerably. I don't know if it is the barrel still breaking in, or some other issue with my load procedure and / or barrel cleaning. Was seeing 2900+, and it started to blow up the group a bit. It is throwing a shot out of the groups, opening them to the high 4s. and 5s. Brass was showing some overpresure and primer pockets are now a bit smoked at 6 firings.

Rimfire match season is starting, lot testing and preparation is using all my available range time. I have not tried tweaking the load, backing it down to that 2820 - 2850 window, hoping it will get that tenth or two back. Also have some fresh Starline and Lapua brass to work with.

prarie dog express · Jan 8, 2024

67rschev said:
I have finished a 6mm ARC bolt action, and there's not a whole lot of data out. . Been fooling with the 6 arc in first a 18 inch and then a 22 in semi for the last year, so I have some baseline and experience with loading the cartridge. Did a shake down was with 10 rounds factory 108 eldm, and then a first ladder that started with Varget and the ( GAP ) Hornady 109 ELDM. Ran the ladder from 26 to 28, with depth at .020 of the lands. Liking what I am seeing, but worried I may be a bit over pressure. Hornady lists 28.1 to be max with the 108 eldm, I'm at 28. Sure seems the loads listed through Hornady seem to be much higher than other loading resources, such as Hodgdon. Ran it through GRT, and the program estimates 65 k using the 110 Atip ( modified in weight ) as the projectile. Brass looks perfect, but this is my first experience with the Nucleus receiver having no plunger ejector. Also, primers look slightly dimples in from pin strike. GRT estimates 26 inch barrel at 2822 fps and i was at ~2750, which would be about perfect.

Any one any experience with said combo or close, or could run this through Quickload if they have the time. Thanks in advance

i have been crazy happy with 27g benchmark, 87g vmax, it's so easy- and 2925, 1/2" is easy and must be easy on barrel- got 9200 plus round on mpa 27" barrel, yest easy 1/2", youtube search this: prarie dog express v.103 send it"

46caliber · Mar 14, 2024

FuhQ said:
I'm running 1x fired and FL sized Hornady brass, CFE-223, CCI 400's, and Nosler 115 RDF's. I'm running all the way up to 29.0gr in 0.5 grain increments (first round of data is pressure baseline and finding a rough node pattern). I'll report back my findings.

What load did you end up settling on? I figured the 115 class projectiles would be too much for the little ARC case.

FuhQ · Mar 14, 2024

46caliber said:
What load did you end up settling on? I figured the 115 class projectiles would be too much for the little ARC case.

6mm ARC (Bolt Action)

Wanted to make this thread for a sticky post for the load data, for those who are shooting a bolt-action 6mm ARC. @Lowlight *** In case someone else reads this in the future, DO NOT use bolt-gun load data in a gas gun. Bolt guns can handle a lot more pressure. *** Loaded up my first round of...

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67rschev · Jan 2, 2025

Been a while since I've updated this thread. Local rimfire season has came to an end, with the cold weather setting in found some centerfire time. A while back I picked up 1000 inexpensive 107 SMK seconds , to use in the semiauto 6 ARC for distance plinking . The base to ogive on these were all over the place, so were sorted into three groups of +- .010 inches. Looking for an inexpensive load to put my inexperienced friends behind for some schooling this month, I tried some in the bolt ARC . I was pleasantly surprised to say the least . After a quick OCW work up, found the middle node at 27 grains of Varget was tight and repeatable. Its a little slow in the low 2700s , but super easy on the brass and barrel. I have only run this load to 200 yards , and will report back to see if it holds together out to 600. 100 yard results , POI change was optic adjustments

Mr. Wolf · Jan 4, 2025

*** Disclaimer, the information below works in my rifle and in my set-up. Work up safely and always follow manufacture published load data ***
Cold windy day for a ladder but load dev is a must for a spring road trip.
6 ARC, Criterion Barrel 26", MTU contour, 45 rounds through the barrel before ladder.
Staball Match 27.6 - 30.3 gr (+0.3 gr), outside temp 24 F. Garmin Xero to grab numbers.
Seated bullets at the lands, compressed load started at 29.4gr

Fed and ejected flawlessly with MDT 6 ARC magazine, no sticky bolt, no ejector smears, primers started showing slight cratering around 29.4gr and more pronounced at 30gr and 30.3gr.
Looks like a possible node at 28.8gr, but slower than what I want to run for PRS. May test around 29.4-29.7gr.

Very impressed by the speed from the Staball Match. I think I'll be able to reach 2835fps target to maximize 6mm bullet efficiency in a 26" bolt gun for PRS. More testing with seating depth for group size and SD soon.

Question: Currently at 60ish rounds through the barrel. With barrel break in and in warmer conditions, is it reasonable to expect 30-50 fps gain?
Your comments, experiences, suggestions welcomed.

YMMV and happy shooting

46caliber · Jan 4, 2025

Mr. Wolf said:
Question: Currently at 60ish rounds through the barrel. With barrel break in and in warmer conditions, is it reasonable to expect 30-50 fps gain?

It will probably speed up some. My XCaliber blank only picked up about 25fps. You might see more. If you've not stocked up on Hornady brass yet, you might want to try Starline. Mine is about 34.8gr of water capacity.

Mr. Wolf · Jan 5, 2025

46caliber said:
It will probably speed up some. My XCaliber blank only picked up about 25fps. You might see more. If you've not stocked up on Hornady brass yet, you might want to try Starline. Mine is about 34.8gr of water capacity.

Already ordered some Alpha 6 ARC brass.
Pricy but I found it to be long lasting. Although slightly less capacity than Hornady brass, it seems to need less charge to reach the same velocity.
Mainly wanted to test Staball Match to see if I could reach my speed goal of 2835fps.
I’ll bump down to 27gr and go up by .3gr as I work up a ladder with the Alpha brass.
YMMV and happy shooting

67rschev · Jan 5, 2025

Mr. Wolf said:
Question: Currently at 60ish rounds through the barrel. With barrel break in and in warmer conditions, is it reasonable to expect 30-50 fps gain?
Your comments, experiences, suggestions welcomed.

YMMV and happy shooting

In my limited experiences , 30-50 fps gain in speed should be expected. Possibly / probably more as I've experienced. This particular barrel is a Shilen select ratchet rifling , finished at 24", mounted to an ARC Nucleus V2 via a barrel nut system. I used the Savage small shank nutted system over having my smith do a direct fit so I could have a little control on head spacing if I so desired. My first foray into 6 arc , was with an Odin 18" gas gun and I saw around 40 fps increase in speed from new through load development. I didn't obtain speed and accuracy goals with that tube using primarily LeverEvolution , so it was replaced with a Rainier Ultra at 22". The Rainier round count is less than 150 , so not enough data to comment on that one.

As stated above, I saw near a 100 fps increase in speed with same lot of powder and projectiles . Dunno if it was a combination of environmental and or loading / cleaning procedures causing the ramp up. Varget is pretty temperature stable , and has been one of my favorite powders across many calibers for years. I have never experienced such a ramp up in speed without explanation. I do know once I reached into the high 2800s into the 2900 area that load fell apart and opened up , and the brass was getting beat. Also on a very important side note , I had miss typed in the posting you quoted. The loading was 27.9 - 28 grain , NOT 28.9 grains as listed in post # 8 , apologies to all.

IMO some important advice is to use Alpha or Starline brass. IME it seems as we need to be near the top of the loading limits , for the 6 ARC to shine . The Hornady stuff will have loose primer pockets after only one or two stout loadings.

Life and other interests have given me the time to continue working with combo, and will explore more and report back.

Old Corps 8541 · Jan 5, 2025

All Pre-de pictures ,but no one mentions what action you'll are using with the non normal {223 & 308} bolts

46caliber · Jan 5, 2025

Mr. Wolf said:
Already ordered some Alpha 6 ARC brass.
Pricy but I found it to be long lasting. Although slightly less capacity than Hornady brass, it seems to need less charge to reach the same velocity.
Mainly wanted to test Staball Match to see if I could reach my speed goal of 2835fps.
I’ll bump down to 27gr and go up by .3gr as I work up a ladder with the Alpha brass.
YMMV and happy shooting

Yeah, you'll be just fine. Less case capacity, means less internal volume, and as a result pressure and velocity will be higher for the same charge.

What I'm curious to see is how your ES and SD look, but more importantly how your velocity readings look in winter, then spring, then summer, etc.

46caliber · Jan 5, 2025

Old Corps 8541 said:
All Pre-de pictures ,but no one mentions what action you'll are using with the non normal {223 & 308} bolts

Most I know with bolt guns in 6ARC are running Zermatt Origin or TL3, Impact 737 or American Rifle Co. Coup de Grace. I went Origin.
There's a handful running Howa 1500 Mini, but those really limit chassis/stock options and you're stuck with their proprietary mag.

67rschev · Jan 5, 2025

All Pre-de pictures ,but no one mentions what action you'll are using with the non normal {223 & 308} bolts

ARC Nucleus v2 here. With ARC and Zermatt It is quite nice having the ability to change bolt heads, also have the .384 and .473 for future caliber considerations

46caliber · Jan 5, 2025

67rschev said:
ARC Nucleus v2 here. With ARC and Zermatt It is quite nice having the ability to change bolt heads, also have the .384 and .473 for future caliber considerations

View attachment 8584050

Controlled round feed and mechanical ejector are the bees knees.

Mr. Wolf · Jan 5, 2025

Old Corps 8541 said:
All Pre-de pictures ,but no one mentions what action you'll are using with the non normal {223 & 308} bolts

I run a Savage SA with the bolt head swap.
Reason explained in this post :

Calling all poors, what is the most poorish shooting sports thing you've ever done?

Let me be the first to say that I am a poor. And poors do shit that makes them even poorer by not following the well established rule of "buy once, cry once." So what project/modification/rabbit hole have you personally chased that embodies the poors ethos? Some of my examples: I poored (pun...

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Another thing about the 6 ARC 26” MTU barrel, I can fire 10-12 shots in a row and the barrel near the throat and the suppressor are luke warm with barely a hint of mirage through the scope.

Gotta love the efficiency.

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6mm ARC Bolt Gun Loadings

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