Help me decipher this

[Clem Bronkoski]

Took the 6mm ARC out this morning with loads using Leverevolution powder and 95 gr Berger VLD bullets @ .030" off the lands. Check out the attachments. My groups were horrible until I got up to the 32.5 gr charge. They gradually got smaller from 31.5 gr to the 32.5 gr but at 32.0 I was getting minor extractor marks on the brass and at 32.5 gr they were a bit mor prevalant but not bad.
It was reall confusing because I had a really good node between 31.5 gr and 32.0 gr right around 3000 fps. At 32.5 gr I was pushing 3050 fps and shooting good.
What should my next step be? I'm considering going .050" off lands and see if that helps lower my pressure and tighten up the groups.
The brass was once fired and run into the sizing die just enough to hold the bullet firmly in place without touching the shoulder.

 

[Clem Bronkoski]

Brass 30.5, 31.0, 31.5, 32.0 and 32.5 left to right. Primers still have nice round corners but I never saw darkening of the primer crater like that. It happened with my other loads also when I upped the powder charge.

 

[Chranah]

As we all know, every barrel is different; and some guys find the charge weight first, and some guys mess with seating depth first, but here's my experience:
I'm a charge weight before seating depth guy.
With a 20" barrel (AR 15) I'm finding that 29.0 gr. of CFE223 is my sweet spot with 95 gr. (SST and Sierra MK BTHP) although that load works well with the 103-105 gr. bullets as well, but I'm getting in the middle 2600's for velocities. I've not pushed as fast as you.
Your ES is similar to mine. I usually get SD's in the teens, sometimes single digits.

I've not done this myself, but many people will tell you that Varget gives more consistency, but with a slight drop in velocity compared to LVR or CFE223.

How is your parallax on your scope adjusted? Do you lift your head in between shots, or do you keep a steady cheek weld until completed with that string.

Is this a hunting rig, or a Long Range Target rig? If hunting, I'd probably be willing to back off on the velocity a bit and find the accuracy node below. And now that I see your cratered primers, I'd back off for that reason as well.

 

[Eric Musgrove]

Is this a bolt gun or AR? I would do a powder test first before messing with anything else.

 

[K.E.C. Darkside]

Brass 30.5, 31.0, 31.5, 32.0 and 32.5 left to right. Primers still have nice round corners but I never saw darkening of the primer crater like that. It happened with my other loads also when I upped the powder charge.View attachment 674911

O my don't load past 31gr.
The black deep crater is showing pressure, pierced primers.

 

[Clem Bronkoski]

O my don't load past 31gr.
The black deep crater is showing pressure, pierced primers.

I looked at them under a strong magnifying glass and they're not pierced and corners are rounded. Also this is a bolt gun and even at 32.5 I'm just under max. If you look at my graph its almost flat between 31.5 and 32.0 gr.

 

[K.E.C. Darkside]

I looked at them under a strong magnifying glass and they're not pierced and corners are rounded. Also this is a bolt gun and even at 32.5 I'm just under max. If you look at my graph its almost flat between 31.5 and 32.0 gr.

Small or are they Large primers.
Small tends to not show flat edge.
Being my experience.

 

[Chranah]

I looked at them under a strong magnifying glass and they're not pierced and corners are rounded. Also this is a bolt gun and even at 32.5 I'm just under max.

That's still a pierced primer in my book.
Just one anecdote here, so take it worth a grain of salt, but also remember "the plural of anecdote is data":
I used MagPro powder for my 7mm RM and found max pressures before the listed max load. That's the first time I found pressure signs before the listed max charge. I'm now a firm believer in starting low and working up slowly.

 

[Clem Bronkoski]

I'm going to load some of these up with CFE223 and see what works. I'll use the gas gun load data and go a bit over that checking pressure signs as I go.
Keep sending replies on this. Its really a fun rifle to shoot.

 

[Chranah]

Its really a fun rifle to shoot.

It's my favorite round to load for and to shoot. I have 3 rifles in this cartridge now.

 

[imyourhuckleberry]

I mean no insult so please don't take it that way. What I see is possibly an issue of trigger control. Before you you do anything else I would recommend you place a dime on the end of the barrel as close as possible. Assume the same position you fired those groups and then squeeze the trigger. If the dime falls you are jerking the trigger. Do this dry fire exercise several times until you can do it 10 times without the dime falling. If the dime stay on the barrel then it could be a cheek weld issue. On the 30.gr group and 32 grain I see some stringing which could possibly be variations in seating depths. All else fails don't give up. It could be your rifle does not like the combination of powder and bullets and you might have to find something else. When it comes to harmonics it is a pain in the butt , but your rifle will tell you what it likes.

 

[Clem Bronkoski]

OK same bullet, different powder/charges. Three shot groups with 10 mins in between. You could actually see the groups open up as the velocity went up. Here are the loads (CFE223) with velocity and group size:
1. 28.6 gr @ 2545fps; .387"
2. 29.0 gr @ 2639fps; .825"
3. 29.4 gr @ 2707fps; .982"
4. 29.8 gr @ 2774fps; 2.152"
5. 30.2 gr @ 2741fps; 2.249"
6. 30.6 gr @ 2815fps; didn't shoot group
My pressure signs before may have been from seating the bullet too deep. They were at 2.170" but I backed them out to 2.250" OAL (Manual called for a 2.260" COAL). This time there was absolutely zero pressure signs (no blackened primers) even with the heaviest load..
The only node I have in this string of charges is between 29.8 and 30.2 but the groups in this area are horrible.
Next trip I'm going to load a few more at 28.6 and 29.0 gr and also load some LVR in that velocity range and seating depth and see what shows up.
I may load at 28.3, 28.6 and 28.9 gr. with the same seating depth.
I'm thinking I may just can the Bergers and shoot the 103 gr ELD-X bullets. Those are shooting under 1/2" and at almost 2900 fps. (heavier bullet and faster speeds for an accuracy decrease of only 19%! (,387" - .473")

*Note these loads are gas gun loads with pressures around 51,000 psi


Huckleberry no trigger jerking. I've been shooting a long long time. That little dot in the reticle was steady in the dot on the target upon firing. And having only 5 rounds per charge I was really focused on making good clean trigger breaks so as not to mess things up.

 

[Hal The Slayer]

I mean no insult so please don't take it that way. What I see is possibly an issue of trigger control. Before you you do anything else I would recommend you place a dime on the end of the barrel as close as possible. Assume the same position you fired those groups and then squeeze the trigger. If the dime falls you are jerking the trigger. Do this dry fire exercise several times until you can do it 10 times without the dime falling. If the dime stay on the barrel then it could be a cheek weld issue. On the 30.gr group and 32 grain I see some stringing which could possibly be variations in seating depths. All else fails don't give up. It could be your rifle does not like the combination of powder and bullets and you might have to find something else. When it comes to harmonics it is a pain in the butt , but your rifle will tell you what it likes.

 

[skipglo]

Brass 30.5, 31.0, 31.5, 32.0 and 32.5 left to right. Primers still have nice round corners but I never saw darkening of the primer crater like that. It happened with my other loads also when I upped the powder charge.View attachment 674911

Next load up and you will be piercing primers...and how does one get...ROUND CORNERS?