Help with looking at data?

GetReel

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ok, so I loaded up 14 rounds to check for pressure signs in my rifle. (Rem 700 6.5CM, 1-8.5, 24”, 147ELDM, IMR 4955, Lapua SR primer, CCI 450 primers.
Book max is 39gr. (Book is listed with LR primers too). I loaded 1 shot each @, 37.4 going up to 40 in .2gr increments. I shot all 14 shots and no pressure signs at all.
I’m assuming the book is on the side of caution.
Looking at a powder burn rate chart, Hodgdon Superformance is right next to IMR 4955 but in the book, they list Superformance at almost 4gr higher load than 4955.
My question…. Would you load up more and keep looking for pressure signs based on that info? Or just start with testing?

Since 4955 is listed at one of the slower velocity powders in this instance, I’d like to get the most out of it as possible. This powder is what I could get my hands on for this project. I’m putting this together to hopefully shoot a PRS match next summer.

Sorry, did not have my chronograph with me testing the pressure sign loads.

I’d like to hear some thoughts.
Thanks,
 

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Dmagna

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I don’t really want to be that guy but without a chrono you kinda don’t know where you atreat. I guess I would get a chrono and load up 3 shots of your highest load and see where you are at. If it’s too slow and you won’t be able to get it higher get a better powder.
 

QuietTexan

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IMR 4955 is extruded and Superperformance is spherical. So SP will have a higher load density, which is how they get 4gn more powder into the case and get more velocity with it.

Hornady book data is generally speaking conservative, and they use SAAMI max COL which removes a significant amount of case volume from the equation for most chamberings. If you're longer than 2.600" I would go higher on the 4955 charge until you see something. You could also use a drop tube to get more of the 4955 into the case if you run out of volume before you hit pressure.

I never start at the bottom of the Hornady chart. Take the max charge and multiply by 93%, that will save you a significant amount of components.
 

GetReel

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I don’t really want to be that guy but without a chrono you kinda don’t know where you atreat. I guess I would get a chrono and load up 3 shots of your highest load and see where you are at. If it’s too slow and you won’t be able to get it higher get a better powder.
I have no problem running another batch. Just more or less wondering if I should keep going higher with powder charge?
 

GetReel

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IMR 4955 is extruded and Superperformance is spherical. So SP will have a higher load density, which is how they get 4gn more powder into the case and get more velocity with it.

Hornady book data is generally speaking conservative, and they use SAAMI max COL which removes a significant amount of case volume from the equation for most chamberings. If you're longer than 2.600" I would go higher on the 4955 charge until you see something.
Ok, I’m limited to magazine length and my Base to Ogive is 2.221” and that leaves about 20-30 thousands to play with. And at 40gr I’m probably in the 95% case capacity range.
 

chav0_12

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I think, without the chronograph to actually try to find a plateau you wasted 40 bullets, 1500grs of powder and 40 primers. If your intention was fireforming then that’s okay, that wouldn’t be a waste. If you chrono’d those rounds you’d have somewhere to go if that’s higher or a flat spot in velo it’d be somewhere. Hornady is typically conservative and if you’re not at SAAMI lengths any book will be low.
 
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StanleyActual

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Yes books er on the side Of caution. Book for my 7RM says max is 68.5-69-ish I believe For H1K and 180’s I’ve run loads up to 71 with no pressure. I like to find pressure so I know where I’m at.

Typically load to first signs of pressure. Back down a 1.5gn or so and adjust seating depth from there. Another way is just to shoot with a chrono. Find a velocity you want and adjust seating depth from there to dial in your groups.

Get a chrono. You need. Magnetos can be had for a fair price and are pretty reliable.
 

GetReel

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I think, without the chronograph to actually try to find a plateau you wasted 40 bullets, 1500grs of powder and 40 primers. If your intention was fireforming then that’s okay, that wouldn’t be a waste. If you chrono’d those rounds you’d have somewhere to go if that’s higher or a flat spot in velo it’d be somewhere. Hornady is typically conservative and if you’re not at SAAMI lengths any book will be low.
I wasn’t trying to find a plateau or anything. Just top pressure. And my question was directed at that.
 

GetReel

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Yes books er on the side Of caution. Book for my 7RM says max is 68.5-69-ish I believe For H1K and 180’s I’ve run loads up to 71 with no pressure. I like to find pressure so I know where I’m at.

Typically load to first signs of pressure. Back down a 1.5gn or so and adjust seating depth from there. Another way is just to shoot with a chrono. Find a velocity you want and adjust seating depth from there to dial in your groups.

Get a chrono. You need. Magnetos can be had for a fair price and are pretty reliable.
I have a chrono, two actually but just forget to bring them. But my question was aimed at the fact if I should continue loading up to look for pressure even though it was above book.
 

StanleyActual

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I have a chrono, two actually but just forget to bring them. But my question was aimed at the fact if I should continue loading up to look for pressure even though it was above book.

Then yes. I’d continue in probably .3gn increments until you found signs pressure. Books are conservative
 

chav0_12

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I wasn’t trying to find a plateau or anything. Just top pressure. And my question was directed at that.
I understood that but without checking the velocities you’re just looking looking to burn components with little gain? You could be finding your node while also looking for pressure. That’s all I’m saying.
 

chav0_12

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I have a chrono, two actually but just forget to bring them. But my question was aimed at the fact if I should continue loading up to look for pressure even though it was above book.
Yes, if your ultimate goal is to just find pressure then keep going until you find it. The book’s data comes from a single rifle chamber. Everything can be different, I typically only look at the book for starting loads. Even then I’ll usually start in the middle(a couple of grains over min, cartridge dependent) because I know that I’m not loading to SAAMI lengths and that pressure will be lower with my parameters than theirs.
 
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ButterBean

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IMR 4955 is extruded and Superperformance is spherical. So SP will have a higher load density, which is how they get 4gn more powder into the case and get more velocity with it.

Hornady book data is generally speaking conservative, and they use SAAMI max COL which removes a significant amount of case volume from the equation for most chamberings. If you're longer than 2.600" I would go higher on the 4955 charge until you see something. You could also use a drop tube to get more of the 4955 into the case if you run out of volume before you hit pressure.

I never start at the bottom of the Hornady chart. Take the max charge and multiply by 93%, that will save you a significant amount of components.
^^^^^^^^^^^^^^^^^^^ Yep ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
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