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Pressure signs with a mechanical ejector?

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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That case is really good at hiding pressure signs. If it were mine, I would back off. 2870 sounds pretty fast for that case in a 22” pipe.
 
That case is really good at hiding pressure signs. If it were mine, I would back off. 2870 sounds pretty fast for that case in a 22” pipe.
Honestly that bullet should get a bit more because of the design, but I’m not worried about crazy speed when it did this with 8 different charges in a ladder. I just backed it down to 2820 fps that shows a velocity node and no pressure signs.

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load data puts a 123 at 2860 fps-ish for a 62k psi load out of a 22" with 6.5 creed. A 6.5x47 is usually 50-100 fps slower. So if you were shooting a lead bullet I'd say your pretty high velocity wise and should probably back down. If that mark is showing up late in your load ladder id probably say that's a clear indicator of pressure. If you found good performance at a lower charge I don't think you need to chase it too much.

With yours being a solid copper I'm not 100% on how that compares load wise to other bullets of the same weight. But the claims made by the manufacturer say they will be significantly faster than bullets of the same weight which would probably account for you matching 22" 6.5 creedmoor velocity before pressure showed up.

I run 450s in my 6.5 creed with lapua srp brass and I always get some amount of cratering on the primer before I get a mark on my brass in a savage 12 lrp. Might never show up on your gun depending on firing pin slop.

Maybe you should run a combo through the gun that is exactly matching load data. And I mean exact. Same bullet, same powder, same OAL. Work up slow with that combo and see what the top end of pressure looks like if you match that loads high end velocity for your barrel length.

It may take some experimenting to find how that brass and primer indicated pressure in that action and barrel.

Maybe check the search bar out to see if other people on the forum talk about how brass indicated pressure with that action.
 
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load data puts a 123 at 2860 fps-ish for a 62k psi load out of a 22" with 6.5 creed. A 6.5x47 is usually 50-100 fps slower. So if you were shooting a lead bullet I'd say your pretty high velocity wise and should probably back down. If that mark is showing up late in your load ladder id probably say that's a clear indicator of pressure. If you found good performance at a lower charge I don't think you need to chase it too much.

With yours being a solid copper I'm not 100% on how that compares load wise to other bullets of the same weight. But the claims made by the manufacturer say they will be significantly faster than bullets of the same weight which would probably account for you matching 22" 6.5 creedmoor velocity before pressure showed up.

I run 450s in my 6.5 creed with lapua srp brass and I always get some amount of cratering on the primer before I get a mark on my brass in a savage 12 lrp. Might never show up on your gun depending on firing pin slop.

Maybe you should run a combo through the gun that is exactly matching load data. And I mean exact. Same bullet, same powder, same OAL. Work up slow with that combo and see what the top end of pressure looks like if you match that loads high end velocity for your barrel length.

It may take some experimenting to find how that brass and primer indicated pressure in that action and barrel.

Maybe check the search bar out to see if other people on the forum talk about how brass indicated pressure with that action.
Just from looking at that chart, my barrel seems to be on the faster side, I’ll have to look back to make 100% sure, but I’m pretty sure I’m at 2600 fps with the 130 gr Berger Hybrid loaded at 2.70” and 35 gr of SW Precision. So far only 23 rounds down the barrel, so it might even speed up more once it settles in around 100-200 rounds.

As for the bullet, yes it’s typically faster. I’m running the 155 in my 280 AI at 3235 fps at a very comfortable pressure.
 
Just from looking at that chart, my barrel seems to be on the faster side, I’ll have to look back to make 100% sure, but I’m pretty sure I’m at 2600 fps with the 130 gr Berger Hybrid loaded at 2.70” and 35 gr of SW Precision. So far only 23 rounds down the barrel, so it might even speed up more once it settles in around 100-200 rounds.

As for the bullet, yes it’s typically faster. I’m running the 155 in my 280 AI at 3235 fps at a very comfortable pressure.
Varget should shoot a 130 at 2600 for top end velocity from 22" (2800 in a 30"). Varget and swp should be really close in max velocity.

Seeing how those marks showed up later in your load ladder I would certainly consider them a pressure sign. If they wash off in a wet tumble with steel pins they are a warning sign. If they stay on there after a wet tumble with pins they are a stop sign.

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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.

fc6f011650fd35f453c59bc6953cfe88.jpg


820699335875d96c0013623afefeafb6.jpg


fb85576f7e2e2482a077a561773ee214.jpg

I'm running a 6br with Lapua brass on my Origin action. Those ejector slot Mark's where prominent like yours on the first firing but tumbled off. Every firing after the mark has been less but it still happens and when tumbled it disappears. I have 4 firings on my brass with a proven under maximum pressure load, H20 weighted. Pockets are like new. I think when you started raising the charge that your new brass was slamming the boltface a little harder causing the mark. Tumble your brass and take a look at it. I can show you 4 time fired brass that's loaded ready to shoot and empty brass I just shot with the slight ejector slot marks on them from the 5th firing they are in the same box. Is everyone posting on here own a Origin?

Don Dunlap
 
It takes a lot of umph to get a solid copper bullet moving into the lands. Could be the load is ok but the pressure building once the bullet gets going, thats why the primer still looks good.
 
I'm running a 6br with Lapua brass on my Origin action. Those ejector slot Mark's where prominent like yours on the first firing but tumbled off. Every firing after the mark has been less but it still happens and when tumbled it disappears. I have 4 firings on my brass with a proven under maximum pressure load, H20 weighted. Pockets are like new. I think when you started raising the charge that your new brass was slamming the boltface a little harder causing the mark. Tumble your brass and take a look at it. I can show you 4 time fired brass that's loaded ready to shoot and empty brass I just shot with the slight ejector slot marks on them from the 5th firing they are in the same box. Is everyone posting on here own a Origin?

Don Dunlap
These were shot with once fired brass. The virgin brass was fired with 35 gr under a 130 Hybrid.
 
So at what level would you worry about pressure?
Most importantly to me is Case Head Expansion in excess of .001. I'm the slow guy at the range, mic'ing his ladder test case heads before and after shooting each one. My experience with Peterson brass (4 different calibers) is that I usually experience annoyingly hard bolt lift, long before I see excessive case head expansion.
 
Most importantly to me is Case Head Expansion in excess of .001. I'm the slow guy at the range, mic'ing his ladder test case heads before and after shooting each one. My experience with Peterson brass (4 different calibers) is that I usually experience annoyingly hard bolt lift, long before I see excessive case head expansion.
I obviously don’t have before and after for each specific case, but my sized cases to fired cases are only showing .0005” growth at most, even the ones with the ejector marks.
 
I obviously don’t have before and after for each specific case, but my sized cases to fired cases are only showing .0005” growth at most, even the ones with the ejector marks.
That's great news. Are you absolutely sure that your chamber was clean and degreased? A little oil here or a little lug grease there can be very sneaky. Even in the magazine, getting on the rounds. I've seen it all, including newly loaded Peterson brass with imprinting. Some worse the others. Not just the extractor but the ejector swiping as well. I swear, its like bobbing for apples in a dark room, trying to suss it all out. Then again, that's what makes it all interesting. I run stuff through QuickLoad that has been adjusted for fired brass water volume. Peterson's usually run stingy but my 6.5x47 ones ended up with a half grain more volume than the default in QL. Go figure. I just about lost my mind trying to get my first 6XC barrel (Remage) to deliver reasonable speeds at charge amounts that others swear by, without having a stiff bolt lift and click. Finally gave up and got a different brand barrel and the problem went away. Just bum luck sometimes.

Hope you get it figured out.
 
That's great news. Are you absolutely sure that your chamber was clean and degreased? A little oil here or a little lug grease there can be very sneaky. Even in the magazine, getting on the rounds. I've seen it all, including newly loaded Peterson brass with imprinting. Some worse the others. Not just the extractor but the ejector swiping as well. I swear, its like bobbing for apples in a dark room, trying to suss it all out. Then again, that's what makes it all interesting. I run stuff through QuickLoad that has been adjusted for fired brass water volume. Peterson's usually run stingy but my 6.5x47 ones ended up with a half grain more volume than the default in QL. Go figure. I just about lost my mind trying to get my first 6XC barrel (Remage) to deliver reasonable speeds at charge amounts that others swear by, without having a stiff bolt lift and click. Finally gave up and got a different brand barrel and the problem went away. Just bum luck sometimes.

Hope you get it figured out.
I swabbed the chamber with alcohol and reran the two top charges, still got marks, but a lower velocity. I loaded 38.1 gr which seemed like a good flat velocity node, and shot a .293” group at 100 yds with ease, at 2803 fps average. That will work for deer season this year, but will continue to tinker further in the spring.

I have noticed that Peterson seems to show very light imprinting on the case head even at some starting loads, just can’t figure out why that is. I’ve heard that the outside layer of brass is softer, but the core is much harder, but I don’t know if that is true or not.
 
I'm also in the beginning phase of working up loads for my 6.5x47L. I'm sure you've already tried this but tell us, with fired cases, will a fresh 6.5 bullet slide down into the necks without resistance? I tend to avoid descriptors like "fall in" with dirty cases. In my 26" Shilen. The 123 Amax bullet hits the lands at 2.70 COL, so I loaded some up earlier this week with a short ladder of RL16 using a .020 jump. They shot slower than QL predicted, even when factoring in the HBN coating. I only went up to 40gr charge in this ladder. That averaged 2815 fps with an awful SD. Grouped poorly too at 100 yds but I'm still getting used to the rifle. Could be my rig just doesn't like RL16 since all the ladder rungs shot poorly (2MOA) off a very good benchrest setup. I mainly chose RL16 because I had not seen many if any reports of others using it. Curiosity... The Petes were on their second firing. My next outing will be the same bullets with a more mainstream powder. If it'll help, that can be Varget. No SWP powders here.
 
I would try to harden up the case heads with an initial load of 35 like you did, but a 2nd load at 37 gr before pushing them that hard.
 

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