Match load question; go with it or back off?

[EchoDeltaSierra]

ARC Nucleus + 21" Criterion barrel + SpecWar 762. This is the load worked up for match shooting using 140gr ELDs over H4350. My current recipe is accurate, low SD, and fast... but, based on this picture, would you go with the load, or back it off some?

 

[morganlamprecht]

dump some water in your mag...shake it out and fire 10 rounds in 90 seconds...thatll let you know for sure

 

[Huskydriver]

Is this out if a lfp or sfp rifle?

 

[MarkLeupold]

Is this out if a lfp or sfp rifle?

The Nucleus is SFP.

To the OP, is the cratering happening with lower charges too?

 

[EchoDeltaSierra]

Is this out if a lfp or sfp rifle?

It’s an ARC Nucleus action; small firing pin.

 

[Huskydriver]

It’s an ARC Nucleus action; small firing pin.

Yea....guy who literally posted above you pointed that out high speed.....?

 

[Precision Underground]

Primer craters are a terrible indicator for pressure. If the bolt lift is absolutely normal I wouldn’t worry about it.

 

[EchoDeltaSierra]

To the OP, is the cratering happening with lower charges too?

It tapers off as I lower the charge.

 

[Huskydriver]

It tapers off as I lower the charge.

Have you measured your fp protrusion by chance?

 

[MarkLeupold]

dump some water in your mag...shake it out and fire 10 rounds in 90 seconds...thatll let you know for sure

I would do this with at least a few rounds. Feel the bolt lift, look for more pressure signs. If you don't see any, I'd call it good.

 

[Broncovan]

Id like to tag in on this if I may.
I have similar cratering with my loads, not quite as bad, but my primers look to be a little flatter. Well, maybe more than a little, there's a barely discernible shoulder on the spent primer. Bolt lift is good.
H4350 with Federal match primers.
12fps spread, very accurate load, for me.
Rifle is a MPA BA.

 

[47guy]

that IS NOT over pressure its a sloppy firing pin/firing pin hole...id shoot that load and never worry about it...there is no REAL way to tell if you are over pressure without pressure trace equipment.

 

[Milo 2.5]

Primer craters are a terrible indicator for pressure. If the bolt lift is absolutely normal I wouldn’t worry about it.

that IS NOT over pressure its a sloppy firing pin/firing pin hole...id shoot that load and never worry about it...there is no REAL way to tell if you are over pressure without pressure trace equipment.

I disagree in this case. That rub around the primer pocket hole on the brass head is from closing the bolt, he is either running an extremely tight bump, or his die is not sizing the base of his case. Either way the casehead is pinned against his bolt face on closure, and that is the only thing keeping his primer radiused, it would be flat otherwise.
I doubt much comes out of ARC out of spec, so I say slop is not the cause.
If he is running a soft cup primer like a 205M, going to a CCI 450 may alleviate the cratering, but if it is a hard cup primer it is close to coughing up other pressure signs.
But I am with you, as long as it cycles for now, I'd run it too, but it is going to warm up soon.

 

[47guy]

I disagree in this case. That rub around the primer pocket hole on the brass head is from closing the bolt, he is either running an extremely tight bump, or his die is not sizing the base of his case. Either way the casehead is pinned against his bolt face on closure, and that is the only thing keeping his primer radiused, it would be flat otherwise.
I doubt much comes out of ARC out of spec, so I say slop is not the cause.
If he is running a soft cup primer like a 205M, going to a CCI 450 may alleviate the cratering, but if it is a hard cup primer it is close to coughing up other pressure signs.
But I am with you, as long as it cycles for now, I'd run it too, but it is going to warm up soon.

so im curious what your thoughts are about the Curtis custom axiom actions as far as tolerances/specs go?
i have 2 of them and both of them do what the OP has pictured...one 6BR running 105s at 2840ish and one 6BRX running 108s at 2940ish.
also i do not see any ejector marks on any of those cases or swipes...i do agree that he may be close and when it warms up he maybe be at pressure but i still do not think he is over pressure now.

 

[RTH1800]

How long are cases lasting? If pocket is loose in 4-5 loadings back it off. If you can load 5-10 or more times it’s fine.

 

[Milo 2.5]

so im curious what your thoughts are about the Curtis custom axiom actions as far as tolerances/specs go?
i have 2 of them and both of them do what the OP has pictured...one 6BR running 105s at 2840ish and one 6BRX running 108s at 2940ish.
also i do not see any ejector marks on any of those cases or swipes...i do agree that he may be close and when it warms up he maybe be at pressure but i still do not think he is over pressure now.

He said his load is fast, using H4350, not really a performance powder, I assume he is close too. Unless he has a shitty paint job on his bolt face, I bet those marks would surface on a unfired chambered rd.
On Curtis actions, no clue, I have been using ARC rings since 2012, top notch, plus I had a MF action, even though it was not for me, it was a supreme piece, in every aspect.

 

[antithesis]

I disagree in this case. That rub around the primer pocket hole on the brass head is from closing the bolt

Maybe. Are you running a pocket uniformer? I know Lapua does not need it, but some people still check which can put a ring in about that same spot. Otherwise, yeah it would be from the bolt but barely would qualify as a wipe.

I would not worry about the cratering at all if it were not for the additional small indentation that is seen with it, but at that the primers are no way near flat enough to have major pressure pushing back on the bolt. You may be on the edge, but on the edge is fine so long as you don't do anything to make it worse. The water test for me would be iffy - I would sooner wipe a fine amount of Hoppes on the case to take up just a small amount of room, but that is me and I only do that when I am ladder testing and really watching things climb.

Bottom line is primers suck as a gauge for checking pressure unless you are putting holes in them or they are ejecting themselves from the case.

You say they are fast, but how fast?

 

[Kwe1982]

What brand primers? CCI?

 

[47guy]

He said his load is fast, using H4350, not really a performance powder, I assume he is close too. Unless he has a shitty paint job on his bolt face, I bet those marks would surface on a unfired chambered rd.
On Curtis actions, no clue, I have been using ARC rings since 2012, top notch, plus I had a MF action, even though it was not for me, it was a supreme piece, in every aspect.

I agree with 99% of what your saying the reason I don’t think he is “OVER” pressure is because I’ve seen those marks and primer flow on several different actions including custom and factory.

And not arguing just throwing my thoughts out.