6mmARC bolt loads

[KMW1954]

This is from my new to me Switchback 6mmARC with a 22" Light Varmint barrel with factory brake.

Just completed shooting 4 powder OCW ladders using a 87gr Hornady VMAX bullet using; BL-C2, TAC, Benchmark and A2460 powders. These were shot at 200yds, bright sun, 50*, 5-7mph steady head wind. 75 rounds in total. All but the BL-C2 were loaded at .5gr increments while the BL was at .3gr increments.

Initial impression was that I was unimpressed with all of these. Only one close to looking as a possibility was a mid-range load with the A2460 which was a complete surprise as there is very little data with this powder. What I can say is that there was a definite POI shift with all 4. The BL-C2 and TAC WERE all high, the Benchmark was low and the A2460 showed the greatest shift from low to high within a full 2grain increase from start to max.. Haven't measured it but looks to be a full 2" shift.

So being new and unfamiliar with this gun and cartridge I don't know yet if the gun doesn't like the bullet, the weight, the powders or if this one just doesn't shoot.

[charlie b]

I wouldn't throw in the towel yet. The longer barrel on my 6BR is more sensitive than that. If had used a 0.3gn ladder I'd have missed one of the nodes. 0.5gn and I might have missed both of them. You might also have a setup with a really bad seat depth.

I start with 3 shot 0.1gn ladder. Depending on bullet I will choose a seat depth that is either jammed or about 0.020 off. When I look at those I pick the range I want and shoot 5 round groups, still 0.1gn. Then I go to seat depth tests.

These days I use a ballistics program, like Quickload or GRT (which is what I use). It can at least let you know how far apart the nodes are. I still run a ladder at 0.1gn difference. Then the obtained vel I can use to adjust the program output.

I also shoot my initial ladder at 100yd to minimize any wind effects.

[GaCop]

I had a 450 Bushmaster barrel with brake on an Axis action. It shot soso with all loads tested. I removed the brake, retested loads and the change in accuracy was amazing.

[Fuj']

Here's a good version to get you deeper into the rabbit hole.....The 6-ARC is basically a necked down
6.5 Grendel. This now make's it close to the 6PPC. The 6PPC has ruled the world in it's class for decades.
It's money making load mainly uses Vhitavouri 133 powder, and a 68gr bullet. Most use Bart's boat tail
avenger bullet jammed.......What Velocities are you at now ?? I will say to try a box of the 70gr HPBT SMK's
And stay between 65 and 75gr bullets......Are you running these from a magazine ??

[KMW1954]

Thanks for the tips and replies all!

Right now the bullet is set at about .008" jamb which was set with a dummy case seated with the bolt. Which is the same way I would do my 223 loads and then start setback.

The thought behind the .5gr powder loads was to basically see if I could eliminate loads of a powder. Which in this case looks like all but maybe the 2460. There was no speeds recorded, just shooting for groups and POI shifts. I do believe I'll reload and test that 2460 loading using .2gr increments. Starting with the 26.0gr load and doing two loads above and two loads below.

Wind was the main reason I shot this all yesterday as it was the lightest winds we have had in week at about 5mph directly towards the benches. Today is heavy overcast and the flag is standing straight out again.

Fug' I get static all the time about wanting a 6ARC Bolt gun but I do know what it is and where it progressed from. Especially the 6PPC. My intention is to use this in a modified bench league to compete with the 6mm BR and Dasher guys at distances of 100-300yds. Believing this should do a bit better at 300yds than the 6PPC.

[Fuj']

i personally would be working more with the Benchmark rifle powder over the AA-2460.
It's a more consistent and has a better temp stability.....Get some of those Sierra 70gr
SMK's and get some velocity numbers. And pics of groups.....

[KMW1954]

Fuj' The picture I have is a mess. I tried to clean it up and indicate which marks are which. I took pictures between ladders but no shot sequence. I did color the holes. Now I wish I had shot these into individual targets.

This is a 7.5:1 twist barrel and load data tells me these should be around 2600-2800fps. with these 87gr VMAX.

If you can make it out to me it looks like the TAC is a waste of time and energy. Though the 26.5gr AA2460 looks the most promising. I keep getting instructed to try LeveRevolution.

[Fuj']

LeveRevolution is too slow......Yeah, Use a separate target per component, and space them a lot further apart.

Not the HPBT SMK but a general idea.....

[South Prairie jim]

Thanks for the tips and replies all!

Right now the bullet is set at about .008" jamb which was set with a dummy case seated with the bolt. Which is the same way I would do my 223 loads and then start setback.

The thought behind the .5gr powder loads was to basically see if I could eliminate loads of a powder. Which in this case looks like all but maybe the 2460. There was no speeds recorded, just shooting for groups and POI shifts. I do believe I'll reload and test that 2460 loading using .2gr increments. Starting with the 26.0gr load and doing two loads above and two loads below.

Wind was the main reason I shot this all yesterday as it was the lightest winds we have had in week at about 5mph directly towards the benches. Today is heavy overcast and the flag is standing straight out again.

Fug' I get static all the time about wanting a 6ARC Bolt gun but I do know what it is and where it progressed from. Especially the 6PPC. My intention is to use this in a modified bench league to compete with the 6mm BR and Dasher guys at distances of 100-300yds. Believing this should do a bit better at 300yds than the 6PPC.

My thoughts on this as a whole, you must enjoy the journey because a 6 br will shoot a hell of a lot smaller than the targets you are producing now with a lot less work and money.
i don’t mean any disrespect it’s just that many experienced wildcatters have tried to out shoot the ppc and 6 br, the 30 br is king for score but if the 223 or 6 arc was up to the task someone would be shooting and winning with it already.