Pressure signs with a mechanical ejector?

slickyboyboo

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What do you guys look for, as far as pressure signs with an action that has a mechanical ejector, such as a Bighorn Origin? This is my first go with one, and I don’t know what to make of it.

Primers are CCI 450s, once fired Peterson Brass, and SW Precision Powder, pushing a 123 gr Absolute Hammer. I’m not getting a stiff bolt, but here are some pics of my case and some of the primer.

I just got the ejector mark at 38.4 and 38.6 gr while running a velocity ladder, but was only at 2870 fps in a 22” barrel.

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MagnumManiac

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ANY flow of brass, like pictured, is a sign that the load is too hot for that brass.
I bet a new primer will be loose going into that brass now.
In most CRF rifles with a blade ejector, ejector marks are already beyond a safe load, regardless of primer appearance, bolt lift and embossing of the case head.
I would be dropping back to a load that produces no ejector marks.
My own 6.5x47 Lapua is on a Rem 700 action, and it will exhibit sticky bolt lift when pressure is exceeded.
Have never seen flat primers with it, I only use small primer brass. I’ve also never run Hammers in it, so I do not know what velocity it should be getting.

Cheers.
 
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slickyboyboo

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Do you know what your brass headspace is compared to your chamber?--- sometimes "undersized" brass can show false pressure signs
I don’t recall of the top of my head, but will check. These cases are once fired in this chamber, and the shoulders bumped 0.002”, so I wouldn’t figure headspace would be the case.
 

can1010

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along with checking headspace have you tried other powders for comparison. my experience with SW precision while accurate is not a top velocity powder. that might be all that is available with your components
 

MagnumManiac

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Do you know what your brass headspace is compared to your chamber?--- sometimes "undersized" brass can show false pressure signs
I would agree with you if the rifle had a plunger type ejector, this can emboss the case head at normal pressures if the case gets a ‘run’ at it.
However, brass flowing into a recess in the bolt face is always an indication that the load is too hot for the hardness of the brass.

To the OP, what primers are you using in that brass?

Cheers.
 

Mike Matteson

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I am detecting some creator in the primer, but also looking at the primers it's not what I call fatten either. Ejector marks is a clear signed on pressures is to high. I feel it's do to something else is a problem. Beyond my pay grade.
 

slickyboyboo

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along with checking headspace have you tried other powders for comparison. my experience with SW precision while accurate is not a top velocity powder. that might be all that is available with your components
SW Precision is faster than what you would ideally run for velocity, but the Absolute Hammers require a faster powder due to their design.
 

Shane Lindsey

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I get these parallel ejector marks on my SR3 as well. I have reduced the loads down to where I did not see them, but decided the powder wasn't going to get me the velocity I wanted.

On another note, in my 308 win, I find that SWP pressures up faster than say Varget, with less velocity. Advertised as better, not so much, but hey it was available.
 

Mike Matteson

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SW Precision is faster than what you would ideally run for velocity, but the Absolute Hammers require a faster powder due to their design.
I don't fallow on faster powder. I would think velocity is what gear the spin with twist rate combined. Is there something I am missing? I can see a faster powder if you have a shorter barrel length to get all the powder burned. At the same time a short barrel reduces the velocity. So I feel that a faster powder would be required in short barrels. Maybe I have answered my question, because he is using a shorter barrel.
 

Shane Lindsey

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I don't fallow on faster powder. I would think velocity is what gear the spin with twist rate combined. Is there something I am missing? I can see a faster powder if you have a shorter barrel length to get all the powder burned. At the same time a short barrel reduces the velocity. So I feel that a faster powder would be required in short barrels. Maybe I have answered my question, because he is using a shorter barrel.

Absolute Hammers are recommended to use faster burning powder than you would normally use for the cartridge. IE H4350 in a RUM with lightweights AH vice the normal slower burning H1000/ Retumbo, etc.

F3E9E932-9FC8-4D43-83E8-40D820234C52.jpeg
 

Hard rock

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Absolute Hammers are recommended to use faster burning powder than you would normally use for the cartridge. IE H4350 in a RUM with lightweights AH vice the normal slower burning H1000/ Retumbo, etc.

View attachment 300644
That is true but if you still have case capacity say from loading the 124 gr hammer and load the 123 gr absolute you still can achieve higher velocities if enough room too increase the powder charge I talked too Steve at hammer bullets and tried it and it worked too the extent of 150 fps plus vel gain with n165 from 3300 too 3450fps saying that I probably still could achieves higher velocity with a little faster powder being I’m at a compressed charge case fill and barrel length will play a big factor in powder selection for the highest vel achieved
 

SSgt G Cody

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Hmmmm. I'd try a little more set-back, maybe .003". Might also try H4350, H1000, and N560. Why do you need more speed? Hunting beyond 500 yds? Extractor marks are a strong indicator of too much pressure!
 

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