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VarmLR

6.5 Creedmoor; Lapua case capacity & life

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That's fine if you feel the need but for me it seems OCD.will you see a difference in you groupings/shooting.i very much doubt it but I've no problem with you proving me wrong.feel free Mac.i am always willing to learn

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“Messing” about is perfectly appropriate in this context ‘cos it means “brass” in German. Whoever has young children will probably find some kneading putty in the play room during a clandestine “raid” :ph34r:.

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2 hours ago, No i deer said:

That's fine if you feel the need but for me it seems OCD.will you see a difference in you groupings/shooting.i very much doubt it but I've no problem with you proving me wrong.feel free Mac.i am always willing to learn

Perhaps I can explain my own take on things.  It has less to do with shrinking group sizes (for me) and more to do with helping piece together a few answers to questions.  I've wondered why I was reaching compressed loads quicker than QL suggests, for one.  I am also trying to get to the bottom of why some of my loads using KVB223 primers were showing pressure signs at relatively modest velocities whilst those using Magnum versions were not.  By finding out more about each element, it helps build a picture of what's going on.  I've found that slightly smaller case capacity used with a hot batch of KVB223's was pushing my loads into high pressures way before the data suggested that it should.

Mind you, I did try batching my brass on my latest loads, and whether that helped to achieve single digit ES figures and tiny groups, I don't really know, but I like to take care at every stage for precision loads.  It's all part of the fun for me, and the moment I stop having fun with it is the time to give it up.  I don't see any of this as a chore but as a learning journey.

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I too am pretty meticulous with case prepp but the case capacity thing is too anal for me.

Primers showing pressure signs early than other primers may purely be due to cup thickness.i think the br2s and 450s have the thickest cup in the sr primer choices being they are magnum primers.my knowledge is years of hearsay from the likes of Laurie Holland who also says don' take quickload data as gospel which to is a parameter guide.if you follow go by what Laurie says you won't go far wrong.

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I'm interested in reducing the extreme spreads of my reloads and as Laurie says, case volume is an important variable.

Using Quickload and my fireformed 22-250 cases as an example, the average case capacity of 52.4gn produce 2713 fps for 60,740psi chamber pressure for my normal load of 41.5gn of H4350 under a 142gn SMK.

The high capacity case of 53.1gn gives 2701 fps for 59515 psi.

but the lower capacity cases increase the velocity to 2732 fps at 62819 psi.

So not only is that a 31 fps predicted difference in velocity, but also indicating the lower case capacities are producing pressures significantly above the 62,000 psi maximum chamber pressure.

Triffid

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2 hours ago, No i deer said:

I too am pretty meticulous with case prepp but the case capacity thing is too anal for me.

Primers showing pressure signs early than other primers may purely be due to cup thickness.i think the br2s and 450s have the thickest cup in the sr primer choices being they are magnum primers.my knowledge is years of hearsay from the likes of Laurie Holland who also says don' take quickload data as gospel which to is a parameter guide.if you follow go by what Laurie says you won't go far wrong.

I have found that QL shouldn't be relied upon for some RS powders which seem to exhibit higher pressures and velocities than it suggests. 

The pressure signs in this case have nothing whatsoever to do with cup thickness but more to do with how hot the primers are.  I have found the current batch of KVB 223 primers that I have are much "hotter" than their SRM stablemates and its more than just primer signs, it's sticky bolt lift and wipe marks on case heads for the same load.  It stands to reason the thicker cups will show less pressure signs.  It's well known that some SR magnum primers can blow with very high pressures with very little warning up to that point.

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2 hours ago, Triffid said:

I'm interested in reducing the extreme spreads of my reloads and as Laurie says, case volume is an important variable.

Using Quickload and my fireformed 22-250 cases as an example, the average case capacity of 52.4gn produce 2713 fps for 60,740psi chamber pressure for my normal load of 41.5gn of H4350 under a 142gn SMK.

The high capacity case of 53.1gn gives 2701 fps for 59515 psi.

but the lower capacity cases increase the velocity to 2732 fps at 62819 psi.

So not only is that a 31 fps predicted difference in velocity, but also indicating the lower case capacities are producing pressures significantly above the 62,000 psi maximum chamber pressure.

Triffid

Yes.  Far from being "anal" about things, it is for the very reason highlighted that it's worth understanding that lower case capacities for a given moderately hot load could push it into "dangerously hot" territory, hence for hotter loads, I have recently acquired the habit of batching cases, or at least ensuring that I check them, and also for reasons of wanting to help with  minimising ES.   Others are free to paddle their own canoes and make their own minds up, and I guess if loading moderate loads for a given brass batch it's not so much of an issue.   

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8 minutes ago, VarmLR said:

Yes.  Far from being "anal" about things, it is for the very reason highlighted that it's worth understanding that lower case capacities for a given moderately hot load could push it into "dangerously hot" territory, hence 6 hotter loads, I have recently acquired the habit of batching cases, or at least ensuring that I check them, and also for reasons of wanting to help with  minimising ES.   Others are free to paddle their own canoes and make their own minds up, and I guess if loading moderate loads for a given brass batch it's not so much of an issue.   

Knowledge is power ;).

If it floats ya boat do it...!

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Garbage in, garbage out ;).

If it floats ya boat, do it...!

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