Once optimal seating depth is found.....

akz28 · May 26, 2024

I found a great powder charge then seating depth combination for my MPA 6.5 Creedmoor.
The problem is that I am getting ejector marks on the brass, which I am in the process of troubleshooting.

My question is, what happens to the accuracy once I start backing off the powder load?
I know that elevation will need to be adjusted on the scope.
But I am talking about the group size. If I shoot 41.0 grains and lets say 2.207 seating depth then what happens if I go to 39 grains?
Will it affect my groups? Or can I theoretically keep the same seating depth and not have to go through that seating depth exercise again.
Again, not talking about elevation, I can adjust for that easily. Will my tight groups be affected.

Thank you in advance.

AllenOne1 · May 26, 2024

I have seen claims that once a seating depth is found it works regardless of power charge and that may be true. Some will find the seating depth and then tune the powder charge. I think most will tune with the powder charge and then fine tune with the seating depth, same as they would with a tuner.

The only way to know for sure is to try it and determine for yourself if it works.

Kfive73 · May 26, 2024

Usually there’s more than 1 accuracy node. If you’re getting pressure signs, I’d look for the slower node and work with that. Might have to start over, but it’s better than hurting yourself or rifle.

There can be a lot of overthinking when reloading. Keep it simple. Consistent velocities, small ES and SD with get you on steel at various distances. If you’re chasing one hole paper punching accuracy, then it can be a different story.

When you’re messing with seating depth, find a few consecutive depths that group well and load for the closes one to the lands- this will keep good grouping as the throat erodes.
Example: I ran my seating depth experiment from 5 thou off the lands all the way to 80 thou off. I found that 50 to 70 thou off were all pretty damn consistent with grouping. So my base to ogive is based on 50 thou off. As the throat erodes another 20 thou (for 70 thou off) my grouping should stay consistent. So, I won’t have to chase the lands anytime soon

spife7980 · May 26, 2024

akz28 said:
My question is, what happens to the accuracy once I start backing off the powder load?

You are the one that has to tell us that

akz28 · May 26, 2024

Yes, but I was hoping to eliminate myself as the reason for the different groupings. I'm not the most experienced shooter. I was hoping to hear from others that would be more definite in their findings.

Kfive73 · May 26, 2024

I think the only definite answer is… if your seeing pressure signs, you probably want to go to the lower node.

Then the question is…. What distance are you shooting, what is your set up, what’s your group size, and are you consistent with that sizing

salks · May 26, 2024

your looking for an easy button and there is not one. Even if someone had found an answer it may not work for you. The only way to know is to SHOOT.

akz28 · May 26, 2024

An easy button? Was asking others for their experiences when it came to changing powder charge after they found their ideal charge and seating depth. You really dont know what I have done or tried up until this point.

Rob01 · May 26, 2024

Leave your seating depth and play with the powder charge to find the load for the rifle. I never play with seating depth. I set it at .020" off if that will fit in mags and if not I set it .010" less than the mag length. I never play the whole load 5 at .001 off and then 5 at .003 off etc. and waste a bunch of components and time.

akz28 · May 26, 2024

Kfive73 said:
I think the only definite answer is… if your seeing pressure signs, you probably want to go to the lower node.

Then the question is…. What distance are you shooting, what is your set up, what’s your group size, and are you consistent with that sizing

Thank you. I was pretty consistent with 41.5 H4350 and a seating depth that was about 20k off jam. Getting 1/4 MOA at 100 and able to hit the same spot on steel at 300y. But that is all this range goes out to. Problem is that it was chewing up my brass. So I have been going back on the load and so far I am down to 38.0 with still signs of high pressure on the brass but my groups have gotten larger. That is why I was asking, so I know if it is me or the changing load. So these comments like"you tell us" or "just SHOOT" from others was not helpful. Because I have been shooting and at the same time trying to figure out if it is me or the changing load. I am going to a range with some friends where I can go up to 1000 yards but its a bit of a drive and I hope to get this sorted out before I go.

Rob01 · May 26, 2024

What range you going to?

Varminterror · May 26, 2024

More often than not, folks are just seeing “nodes” where they want to see them, and not really getting true feedback, valid feedback, from the load. What we’ve been doing for a long, long time has been finding confidence in coincidence. Largely, we have been finding loads that shoot small because that’s what physics and thermodynamics want them to do, and we have not actually been culling out bad loads in between.

Don’t overthink it. If it shoots small, with stable velocities, run it.

4O6shootist · May 26, 2024

akz28 said:
Thank you. I was pretty consistent with 41.5 H4350 and a seating depth that was about 20k off jam. Getting 1/4 MOA at 100 and able to hit the same spot on steel at 300y. But that is all this range goes out to. Problem is that it was chewing up my brass. So I have been going back on the load and so far I am down to 38.0 with still signs of high pressure on the brass but my groups have gotten larger. That is why I was asking, so I know if it is me or the changing load. So these comments like"you tell us" or "just SHOOT" from others was not helpful. Because I have been shooting and at the same time trying to figure out if it is me or the changing load. I am going to a range with some friends where I can go up to 1000 yards but its a bit of a drive and I hope to get this sorted out before I go.

You're dealing with a bigger problem if 38.X grains is showing same psi signs that 41.5gr was. 41.5 H4350 with a 140 anything is a very common place to be running 2700-2800 depending on brass and barrel length.

Kfive73 · May 26, 2024

How many rounds down the barrel? Could be carbon ring?

akz28 · May 26, 2024

4O6shootist said:
You're dealing with a bigger problem if 38.X grains is showing same psi signs that 41.5gr was. 41.5 H4350 with a 140 anything is a very common place to be running 2700-2800 depending on brass and barrel length.

I agree 100%. Although the marks on the brass are not as bad at 38gr than they were at 41.5 but they are still there. And everyone that saw the brass at the range agree that it is pressure. I have messages in to Curtis and MPA but have not heard back yet to hear as to what they have to say. I am down to 38gr and low 2600's FPS and still getting pressure marks on the brass This rifle should be doing way better than that. My 6.5cm Tikka had no problem handling 41.5 H4350. Just for kicks I am trying 36, 36.5, 37 and 37.5 tomorrow at the range. But this is just to see when the marks stop. I should be able to do way more than that.

akz28 · May 26, 2024

Kfive73 said:
How many rounds down the barrel? Could be carbon ring?

I have cleaned the barrel but not particularly the carbon ring. I will try that.

Rob01 · May 26, 2024

What do the primers look like? Ejector marks aren't always a sign of pressure. You may be bumping the shoulder back too far when sizing and having some jump in there.

Where are you going to shoot 1000?

4O6shootist · May 26, 2024

akz28 said:
I agree 100%. Although the marks on the brass are not as bad at 38gr than they were at 41.5 but they are still there. And everyone that saw the brass at the range agree that it is pressure. I have messages in to Curtis and MPA but not have heard back yet to hear what they have to say. I am down to 38gr and low 2600's FPS and still getting pressure marks on the brass This rifle should be doing way better than that. My 6.5cm Tikka had no problem handling 41.5 H4350. Just for kicks I am trying 36, 36.5, 37 and 37.5 tomorrow at the range. But this is just to see when the marks stop. I should be able to do way more than that.

How cleans the barrel? Recent? Been a while? I'd strip that sucker down, some clr and thoroclean, make it shine. Start over at 39gr and work up. Clean the barrel, chamber, make sure it's all. 1000% dry and no fluids left anywhere, clean the action, give a lil bit of grease to the back the bolt lugs. While your at it, inspect the lugs, do all 3 have equal wear? One more than the other? Some that appear to have no wear? Sometimes things don't get machined properly, one lug/abutment will take the load of the chamber, gives pressure signs that aren't caused by anything going on in the chamber. Check your ejector plunger, is it rough or sharp on the edges? Excessive spring pressure? Some these things will give ejector marks when they shouldn't. These are all lessons learned having owned a few terminus actions, they're designed by the same guy who designed all the Curtis actions.

Mpa uses Spencer barrels I believe, shouldn't be anything wrong here, but everyone makes a bad product once in a while. Curtis actions, well.......good luck getting a response from Chase. Worst customer service in the action industry.

Best of luck, hope some this info is insightful, you should be able to get it figured out.

akz28 · May 26, 2024

Rob01 said:
What do the primers look like? Ejector marks aren't always a sign of pressure. You may be bumping the shoulder back too far when sizing and having some jump in there.

Where are you going to shoot 1000?

No sign of primer crating. Shot brass is around 1.527. I bump it back to 1.525 and followed the advice of Cortina....strip the bolt down and bump until it sort of gently falls. Going to Colemans Creek in Ellerbe, NC. You can actually do a mile there.

akz28 · May 26, 2024

4O6shootist said:
How cleans the barrel? Recent? Been a while? I'd strip that sucker down, some clr and thoroclean, make it shine. Start over at 39gr and work up. Clean the barrel, chamber, make sure it's all. 1000% dry and no fluids left anywhere, clean the action, give a lil bit of grease to the back the bolt lugs. While your at it, inspect the lugs, do all 3 have equal wear? One more than the other? Some that appear to have no wear? Sometimes things don't get machined properly, one lug/abutment will take the load of the chamber, gives pressure signs that aren't caused by anything going on in the chamber. Check your ejector plunger, is it rough or sharp on the edges? Excessive spring pressure? Some these things will give ejector marks when they shouldn't. These are all lessons learned having owned a few terminus actions, they're designed by the same guy who designed all the Curtis actions.

Mpa uses Spencer barrels I believe, shouldn't be anything wrong here, but everyone makes a bad product once in a while. Curtis actions, well.......good luck getting a response from Chase. Worst customer service in the action industry.

Best of luck, hope some this info is insightful, you should be able to get it figured out.

Great advice....thank you !

akz28 · May 26, 2024

Rob01 said:
What range you going to?

DPRC.

Rob01 · May 26, 2024

akz28 said:
No sign of primer crating. Shot brass is around 1.527. I bump it back to 1.525 and followed the advice of Cortina....strip the bolt down and bump until it sort of gently falls. Going to Colemans Creek in Ellerbe, NC. You can actually do a mile there.

.002" shoulder bump isn't bad. I set mine at .001" so barely any movement. Shouldn't get issues with .002". Do what 406 said and see if any of it helps.

I was thinking it was Coleman's or Frontline. My name is on the wall at Coleman's for hitting the 12" gong at the mile. It's an awesome range. You will have fun there.

I shoot some of the .22 matches at DPRC. It's a nice range too. I am a member at Woody's.

Genin · May 26, 2024

Rob01 said:
Leave your seating depth and play with the powder charge to find the load for the rifle. I never play with seating depth. I set it at .020" off if that will fit in mags and if not I set it .010" less than the mag length. I never play the whole load 5 at .001 off and then 5 at .003 off etc. and waste a bunch of components and time.

This^^^^. My mags are my factor as well. I don’t play with seating depth either for that reason. Just charges, find the node, tweak it, load a bunch and shoot.

akz28 · May 27, 2024

Rob01 said:
.002" shoulder bump isn't bad. I set mine at .001" so barely any movement. Shouldn't get issues with .002". Do what 406 said and see if any of it helps.

I was thinking it was Coleman's or Frontline. My name is on the wall at Coleman's for hitting the 12" gong at the mile. It's an awesome range. You will have fun there.

I shoot some of the .22 matches at DPRC. It's a nice range too. I am a member at Woody's.

Rob01, I just rejoined Woody's last night. I had my membership on pause as I was helping out my 95 year old dad after he had some health issues. I didn't get out to shoot much these past few months but I am able to get out again pretty often. So I'll be getting out to Woodys again but i missed my chance to qualify for the 1000 yard range when my name came up. I am grandfathered in to the 550.

Rob01 · May 27, 2024

akz28 said:
Rob01, I just rejoined Woody's last night. I had my membership on pause as I was helping out my 95 year old dad after he had some health issues. I didn't get out to shoot much these past few months but I am able to get out again pretty often. So I'll be getting out to Woodys again but i missed my chance to qualify for the 1000 yard range when my name came up. I am grandfathered in to the 550.

Maybe I will see you out there. I will be in the truck with the license plate Rob01. Lol

akz28 · May 27, 2024

I'll keep an eye out for you. I use to shoot with Alex a lot before he passed away. You might have known him since he was a regular there. I also know Gary S.

Rob01 · May 27, 2024

Yup I shoot matches with Gary a lot and meet at Woody’s when I can. He is here on the site too. I might have known Alex by site but I am usually horrible with names. Lol

mark5pt56 · May 27, 2024

You may also want to check your chamber neck length and then the brass. I would say it may be this along with or the carbon ring.

akz28 · May 27, 2024

Update with some new data. Did a thorough cleaning....barrel, chamber, bolt. Cleaned the carbon ring area with Bore Tech C4 Then used Bore Tech Eliminator and Copper remover for the rest. Loaded some lighter rounds for pressure testing. Found that 36.5gr of H4350 is the highest I can go without leaving a mark on the brass with a 2526 avg FPS. Not great by any means. Hope to hear back from MPA tomorrow to see what they have to say. Funny thing is that I shot some factory Hornady 140 ELD-M which left a light mark on the brass but got me a 2787 avg FPS and left a very light mark on the brass. Not great groups, but a good FPS. The mark it left was about the equivalent of the mark when I shot 37.0 of H4350 which only got me 2566 avg FPS. Wish I knew what powder was in the stock Hornady to give that a try.

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akz28 · May 27, 2024

Rob01 said:
Yup I shoot matches with Gary a lot and meet at Woody’s when I can. He is here on the site too. I might have known Alex by site but I am usually horrible with names. Lol

Alex was the guy whose wife Elizabeth had dementia, so he would park the car in the shade so she could read her books without getting out and trying to wander down range. It was pretty sad as that progressed.

Also, if Gary ever told you the story about the guy that got his Vudoo stolen by FedEx, that was me lol.

Rob01 · May 27, 2024

akz28 said:
Update with some new data. Did a thorough cleaning....barrel, chamber, bolt. Cleaned the carbon ring area with Bore Tech C4 Then used Bore Tech Eliminator and Copper remover for the rest. Loaded some lighter rounds for pressure testing. Found that 36.5gr of H4350 is the highest I can go without leaving a mark on the brass with a 2526 avg FPS. Not great by any means. Hope to hear back from MPA tomorrow to see what they have to say. Funny thing is that I shot some factory Hornady 140 ELD-M which left a light mark on the brass but got me a 2787 avg FPS and left a very light mark on the brass. Not great groups, but a good FPS. The mark it left was about the equivalent of the mark when I shot 37.0 of H4350 which only got me 2566 avg FPS. Wish I knew what powder was in the stock Hornady to give that a try.

Sounds like an ejector issue and not a pressure issue. I would not stress the marks on the case head if primers look fine. as mentioned by someone the ejector probably needs some filing down.

And Hornady uses a powder that is not available to hand loaders. H4350 was the original powder used and what the round was developed around so stick with it.

akz28 · May 27, 2024

Rob01 said:
Sounds like an ejector issue and not a pressure issue. I would not stress the marks on the case head if primers look fine. as mentioned by someone the ejector probably needs some filing down.

And Hornady uses a powder that is not available to hand loaders. H4350 was the original powder used and what the round was developed around so stick with it.

Thanks Rob !

BuildingConceptsllc · May 27, 2024

Rob01 said:
Sounds like an ejector issue and not a pressure issue. I would not stress the marks on the case head if primers look fine. as mentioned by someone the ejector probably needs some filing down.

And Hornady uses a powder that is not available to hand loaders. H4350 was the original powder used and what the round was developed around so stick with it.

As has been mentioned, ejector marks aren't always a sign of pressure if that's the only thing being seen.

OP: are you experiencing any hard bolt lift or anything like that?

1.527" is what your fired brass measures? What comparator are you using to get that measurement? Is that with your primer knocked out or in? 1.541" is a GO gauge so , am I missing something here ? NO GO is 1.5450"

akz28 · May 27, 2024

BuildingConceptsllc said:
As has been mentioned, ejector marks aren't always a sign of pressure if that's the only thing being seen.

OP: are you experiencing any hard bolt lift or anything like that?

1.527" is what your fired brass measures? What comparator are you using to get that measurement? Is that with your primer knocked out or in? 1.541" is a GO gauge so , am I missing something here ? NO GO is 1.5450"

1.527 is the fired brass with the primer removed. I shoulder bump back to 1.525. I use the .400 comparator that came with my Whidden die set. At that length the stripped bolt falls gently down. I dont have any issues loading rounds at 1.525.

BuildingConceptsllc · May 27, 2024

akz28 said:
1.527 is the fired brass with the primer removed. I shoulder bump back to 1.525. I use the .400 comparator that came with my Whidden die set. At that length the stripped bolt falls gently down. I dont have any issues loading rounds at 1.525.

Ok, well I don't have any point of reference with that comparator so it's hard to say. It just looks like it's pretty short with those numbers but, that could be just how it's being measured and not an issue.

Rob01 · May 27, 2024

For some reference I just checked my 6.5 Creedmoor brass that is sized and ready to load with the Hornady comparator with the D .400 adapter in there and my brass is 1.535". I checked a brand new cartridge and it was 1.533". I also checked my once fired and it was 1.536".

4O6shootist · May 27, 2024

There is always a huge difference in comperators. I use a whidden 0.400 bump gauge just like @akz28, and my fired cases are 1.518, and I size to 1.516. New lapua brass measure 1.5135-1.5145 with same gauge. My chamber is cut to go gauge plus 0.002". Same smith has cut me numerous 22, 6, 25, and 65cm barrels and they have all been within 0.001 headspace.

Rob01 · May 27, 2024

It would be interesting to check a piece of his brass with my comparator. Maybe if I see him at the range I can grab a piece and see.

BuildingConceptsllc · May 27, 2024

Its probably just comp meaaurement difference but I just thought it may be worth checking with the mysterious pressure issue

4O6shootist · May 27, 2024

BuildingConceptsllc said:
Its probably just comp meaaurement difference but I just thought it may be worth checking with the mysterious pressure issue

I quite certain is just machining tolerances.

akz28 · May 28, 2024

I'm using the same comparator to check fired and sized brass. So if it is off I am not sure it would matter since I am going back 2k from the fired brass measurement with the same comparator. But I do have a second .400 comparator that came with a different die set and will check today.

Varminterror · May 28, 2024

akz28 said:
I'm using the same comparator to check fired and sized brass. So if it is off I am not sure it would matter since I am going back 2k from the fired brass measurement with the same comparator. But I do have a second .400 comparator that came with a different die set and will check today.

Does your fired brass close back into your chamber? How does your fired brass measure vs. the actual headspace of your chamber?

4O6shootist · May 28, 2024

akz28 said:
I'm using the same comparator to check fired and sized brass. So if it is off I am not sure it would matter since I am going back 2k from the fired brass measurement with the same comparator. But I do have a second .400 comparator that came with a different die set and will check today.

Don't do it! Lol I had two 420 whidden comperators, gave one away as it was like 008 different than the one I normally use.

akz28 · May 28, 2024

4O6shootist said:
Don't do it! Lol I had two 420 whidden comperators, gave one away as it was like 008 different than the one I normally use.

Same here. i have three of the Whidden comparators. Two measure exactly the same. The third one is about 4k off .So I dont use that one.

akz28 · May 28, 2024

I invested in a bore scope since it was guesswork as to whether I was getting the carbon ring scrubbed good enough. So yesterday I spent a good bit of time getting rid of the carbon ring with Bore Tech C4 and then inspecting with the bore scope. The result was that today I was able to shoot some rounds with 40.0, 40.5 and 41.0 with NO MARKS ! Guess I should have invested in that bore scope before wasting all those components, but lesson learned.

So I want to give a big THANK YOU to everyone that reached out to help. I always considered firearm enthusiasts a brotherhood and most of you didn't try to make me feel stupid and just wanted to help. I thank you very much for that. Case closed.....thanks again

4O6shootist · May 28, 2024

akz28 said:
I invested in a bore scope since it was guesswork as to whether I was getting the carbon ring scrubbed good enough. So yesterday I spent a good bit of time getting rid of the carbon ring with Bore Tech C4 and then inspecting with the bore scope. The result was that today I was able to shoot some rounds with 40.0, 40.5 and 41.0 with NO MARKS ! Guess I should have invested in that bore scope before wasting all those components, but lesson learned.

So I want to give a big THANK YOU to everyone that reached out to help. I always considered firearm enthusiasts a brotherhood and most of you didn't try to make me feel stupid and just wanted to help. I thank you very much for that. Case closed.....thanks again

Glad you fixed it! CLR will kill a carbon ring faster than anything else. Just neutralize it with alcohol after. Been using it for years. Hasn't done anything to a negative affect on my non Bartlein barrels. Frank Green says it'll damage his barrels, so Bartlein is worthless to me.

akz28 · May 28, 2024

Rob01 said:
Maybe I will see you out there. I will be in the truck with the license plate Rob01. Lol

I have a white silverado trail boss. Hope to see you there. I usually will stop at the DPRC matches when I see that blue BMW to say hi to Gary.

Rob01 · May 28, 2024

akz28 said:
I have a white silverado trail boss. Hope to see you there. I usually will stop at the DPRC matches to say hi to Gary when he is there.

Will probably be at Woody's Friday morning to run some rounds for my Saturday match. Will also be at the DPRC .22 match on June 9th in Gary's group. You shooting that match?

akz28 · May 29, 2024

If Friday is a light work day I will stop at Woody's. I am planning on shooting that match on the 9th. I haven't shot a match yet and I'm looking forward to it.

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