10-26-2020, 01:13 AM
So I got in some of Horandy's factory "Black" 6mm ARC ammo (105 gr BTHP) and their "Match" 6mm ARC ammo (108 gr ELD) and after a go over of it before starting actual range testing (i.e. shooting them), all I am going to say is Hmmmm!
The "Black" ammo is loaded at right around 2.200" OAL which gives the bullet a jump of just about .040" to the lands on a SAAMI 6mm ARC chamber (at least the one I have).
The "Match" ammo is loaded right around 2.250" OAL which also gives the bullet a jump of just about .040" to the lands on the SAAMI 6mm ARC chamber (at least the one I have).
I pulled down a number of cartridges to measure the powder loads and just to see what was going on inside and here's what I found:
Both the "Black" and the "Match" are loaded with a ball powder that looks like a dead ringer for Hodgdon's CFE223 and the loadings also bespeak of a powder of a similar burn rate. In addition, the loads of both are under heavy compression. To get the powder out of the cases after pulling the bullets, I had to hold each case horizontally over a metal cup and insert a wooden toothpick in the case as I spun it to break up the solid chunk of powder in the case caused by the compression. Even then, the powder came out with clumps of the powder stuck together from compression. IMO - not exactly the recipe for accurate loadings (i.e. ball powder under heavy compression).
The loading of the "Black" varied from 30.12 gr to 30.38 gr..
The loadings of the "Match" varied from 30.58 gr to 30.60 gr..
New factory brass was just under the "go" headspace dimension which means if a "go" gage goes in your chamber, so will the ammo, headspace wise. The brass length of the cases hovered around 1.485" OAL.
The 105 gr bullets of the "Black" were right around 1.225" in OAL, which means that when the cartridge is loaded at 2.200" OAL you have around .715" of the bullet sticking out of the brass and .510" of the bullet back in the case. Since the neck of the brass is right around .230" long, that put's another .280" of bullet back beyond the neck/shoulder junction - - ergo why there is heavy compression of the powder. As an aside, the pulled down powder, when poured back in the case, after pull down, sits right about at the neck/shoulder junction.
Similar results with the 108 ELD bullet. The 108's of the "Match" were right around 1.265" in OAL, which means that when the cartridge is loaded at 2.250" OAL you have around .765" of the bullet sticking out of the brass and .500" of the bullet back in the case. Since the neck of the brass is right around .230" long, that puts another .270" of bullet back beyond the neck/shoulder junction - - ergo why there is heavy compression of the powder, especially since the charge for the 108's was greater than for the 105's. Once again, the pulled down powder, when poured back in the case after pull down, sits right about at the neck/shoulder junction.
Just my personal impressions - - I love accurate rifles and accurate ammo is an essential ingredient to them. If the powder is CFE 223, and I believe it is, those are loads we tested in the 6mmAR, but those are not loads we shot or used with the 6mmAR because, while they got the velocity and pressure numbers, they never proved to be consistently accurate. FWIW - I never found heavily compressed loadings of any power to be particularly accurate, and ball powders are not the best for consistent accuracy either IMO.
Now Hornady touts that the 6mm ARC was made up as a cartridge for military use, so I assume it's about man sized targets. I can only say that for real accuracy work in the 6mmAR, despite the testing of numerous powders, we always came back to stick powders, and not under compression at all (if possible).
So I am going to range test these loadings, but I am not optimistic as far as their promise for consistent accuracy - - but we'll see!
Robert
The "Black" ammo is loaded at right around 2.200" OAL which gives the bullet a jump of just about .040" to the lands on a SAAMI 6mm ARC chamber (at least the one I have).
The "Match" ammo is loaded right around 2.250" OAL which also gives the bullet a jump of just about .040" to the lands on the SAAMI 6mm ARC chamber (at least the one I have).
I pulled down a number of cartridges to measure the powder loads and just to see what was going on inside and here's what I found:
Both the "Black" and the "Match" are loaded with a ball powder that looks like a dead ringer for Hodgdon's CFE223 and the loadings also bespeak of a powder of a similar burn rate. In addition, the loads of both are under heavy compression. To get the powder out of the cases after pulling the bullets, I had to hold each case horizontally over a metal cup and insert a wooden toothpick in the case as I spun it to break up the solid chunk of powder in the case caused by the compression. Even then, the powder came out with clumps of the powder stuck together from compression. IMO - not exactly the recipe for accurate loadings (i.e. ball powder under heavy compression).
The loading of the "Black" varied from 30.12 gr to 30.38 gr..
The loadings of the "Match" varied from 30.58 gr to 30.60 gr..
New factory brass was just under the "go" headspace dimension which means if a "go" gage goes in your chamber, so will the ammo, headspace wise. The brass length of the cases hovered around 1.485" OAL.
The 105 gr bullets of the "Black" were right around 1.225" in OAL, which means that when the cartridge is loaded at 2.200" OAL you have around .715" of the bullet sticking out of the brass and .510" of the bullet back in the case. Since the neck of the brass is right around .230" long, that put's another .280" of bullet back beyond the neck/shoulder junction - - ergo why there is heavy compression of the powder. As an aside, the pulled down powder, when poured back in the case, after pull down, sits right about at the neck/shoulder junction.
Similar results with the 108 ELD bullet. The 108's of the "Match" were right around 1.265" in OAL, which means that when the cartridge is loaded at 2.250" OAL you have around .765" of the bullet sticking out of the brass and .500" of the bullet back in the case. Since the neck of the brass is right around .230" long, that puts another .270" of bullet back beyond the neck/shoulder junction - - ergo why there is heavy compression of the powder, especially since the charge for the 108's was greater than for the 105's. Once again, the pulled down powder, when poured back in the case after pull down, sits right about at the neck/shoulder junction.
Just my personal impressions - - I love accurate rifles and accurate ammo is an essential ingredient to them. If the powder is CFE 223, and I believe it is, those are loads we tested in the 6mmAR, but those are not loads we shot or used with the 6mmAR because, while they got the velocity and pressure numbers, they never proved to be consistently accurate. FWIW - I never found heavily compressed loadings of any power to be particularly accurate, and ball powders are not the best for consistent accuracy either IMO.
Now Hornady touts that the 6mm ARC was made up as a cartridge for military use, so I assume it's about man sized targets. I can only say that for real accuracy work in the 6mmAR, despite the testing of numerous powders, we always came back to stick powders, and not under compression at all (if possible).
So I am going to range test these loadings, but I am not optimistic as far as their promise for consistent accuracy - - but we'll see!
Robert