Reloading 6mm ARC Prelim

[457ciSBC]

So my intent to use the gun was as a repeating live varmint gun and so most of the rounds that I have loaded so far are between 58 and 90 grains in weight. I have noticed that the throat seems pretty short on my barrel. I need to make some base to ogive reference measurements, but the generic 90 grain FMJ at 2.175 is jammed into the lands and I was surprised at the jam distance of the 65 grain VMAX. I have 106 grain tip pills to try as well.

Also on a virgin case; 33 grains of Lever is at the base of the neck and the 103 ELDX seated at 2.250 heavily compresses 29.5 grains of Lever.

Just wondering what others have experienced so far.

 

[457ciSBC]

Looking at the SAAMI reamer, .124 is definitely a short throat for 1.5 degree.

 

[gunsandgunsmithing]

Looking at the SAAMI reamer, .124 is definitely a short throat for 1.5 degree.

I wouldn't think so but while I've got a pretty good amount of experience with a 6 Grendel, I have none with the ARC. But, neck length is about the same, is it not?

I use .070 freebore in a 6 Grendel and it works well with 68-105 class bullets. If I were gonna do one specifically for 80-105's, I'd go with about .100, roughly.

 

[457ciSBC]

The SAMMI 6 ARC freebore is .089, but it’s the actual throat(.124)
thats appears short. When I compare it to let’s say my 6PPC Boyer, or 6BR (.035 fb, short throated ) varmint reamer. The SAMMI 6 ARC has less throat than my 6PPC match or 6BR varmint reamers. For comparison look at the Grizzly 6PPC print or the 6BR Norma finish prints.That Grizzly 6PPC reamer has a .045 fb and a .200 throat and it seems to me that .124 would be a somewhat short throat for the 6 ARC and 103-108 bullets.

Just found this, knew I wasn’t crazy....

Range Report - Hornady 6mm ARC ammunition failure

I took my new Odin Works 6mm ARC complete upper out to the Panteo range today to zero and get some initial data on the new cartridge. As I was about 12 rounds in, the range went cold so another shooter could replace and check his target so I safed my rifle and ejected the chambered round. After...

www.snipershide.com

Apparently there’s at least two reamers now, can we say 6mm ARC v2.0 chamber

I loaded the 103 ELD-x at 2.250 and pretty sure they will not chamber in this barrel.

 

[gunsandgunsmithing]

The SAMMI 6 ARC freebore is .089, but it’s the actual throat(.124)
thats appears short. When I compare it to let’s say my 6PPC Boyer, or 6BR (.035 fb, short throated ) varmint reamer. The SAMMI 6 ARC has less throat than my 6PPC match or 6BR varmint reamers. For comparison look at the Grizzly 6PPC print or the 6BR Norma finish prints.That Grizzly 6PPC reamer has a .045 fb and a .200 throat and it seems to me that .124 would be a somewhat short throat for the 6 ARC and 103-108 bullets.

Just found this, knew I wasn’t crazy....

Range Report - Hornady 6mm ARC ammunition failure

I took my new Odin Works 6mm ARC complete upper out to the Panteo range today to zero and get some initial data on the new cartridge. As I was about 12 rounds in, the range went cold so another shooter could replace and check his target so I safed my rifle and ejected the chambered round. After...

www.snipershide.com

Apparently there’s at least two reamers now, can we say 6mm ARC v2.0 chamber

I loaded the 103 ELD-x at 2.250 and pretty sure they will not chamber in this barrel.

You just can't compare a ppc or br to the arc, as you're trying to do...at least not without figuing the difference in neck length into it. Also, My post does not consider mag length limitations but is based on where the stated freebore places the base or heel of the bullet in relation to the neck shoulder junction.

According to the saami chamber drawing, the arc has .0899 freebore. The throat length is irrelevant and that number will change based on the print and bore diameter. What matters is where the taper begins, not where it ends, which is what I think you're confusing when you refer to throat length.

Freebore is from the end of the chamber and the start of the, in this case 1.5° leade angle.

I'm speculating about the Hornady issue you linked but they offer tangent and secant ogive bullets. If you study on both, you'll see why that issue may be related to a secant ogive but regardless, bullet design also is a factor in proper freebore length.

I'll bow out and let you all hash this out but you can't compare a ppc or br for freebore length, to the arc, with or without regard for mag length.

 

[457ciSBC]

You just can't compare a ppc or br to the arc, as you're trying to do...at least not without figuing the difference in neck length into it. Also, My post does not consider mag length limitations but is based on where the stated freebore places the base or heel of the bullet in relation to the neck shoulder junction.

According to the saami chamber drawing, the arc has .0899 freebore. The throat length is irrelevant and that number will change based on the print and bore diameter. What matters is where the taper begins, not where it ends, which is what I think you're confusing when you refer to throat length.

Freebore is from the end of the chamber and the start of the, in this case 1.5° leade angle.

I'm speculating about the Hornady issue you linked but they offer tangent and secant ogive bullets. If you study on both, you'll see why that issue may be related to a secant ogive but regardless, bullet design also is a factor in proper freebore length.

I'll bow out and let you all hash this out but you can't compare a ppc or br for freebore length, to the arc, with or without regard for mag length.

I agree about the comparison and of course they can’t be exact apple to apple, because of the varying neck length. I was just trying make a general baseline. I have always viewed that “gross freebore” as two parts, the leade and the throat. I appreciate the response and dialogue.

I’m cool with it actually, because the larger lengths I’m shooting in 6CM anyway. If I can get the 65/75VMAX, 70 Blitz and 80 Berger to shoot in this ARC half decent, I’m good with this setup.