Adding grains relative to veocity gains?

[kingfamous]

Sorry if this is a dumb question, but im trying to clone some factory rounds right now for the 5.56. im using wc844 for my powder, LC brass, and milsurp. m193 bullets. These are figures just for an example, but my question is if you load was 25 grains and your getting 3100fps and then you add .5grains to get 25.5 at 3125fps does this mean that for every .5 grains the relative velocity gain will be 25fps?

[dskit]

No


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[kingfamous]

so basically its a work up in grains until the desired fps is reached. thanks

[JMP]

my question is if you load was 25 grains and your getting 3100fps and then you add .5grains to get 25.5 at 3125fps does this mean that for every .5 grains the relative velocity gain will be 25fps?

No, that is not at all how it works. The system is nonlinear. As you approach maximum pressures, you will see spiking.

[kingfamous]

So say factory federal ammo is at 3100fps out of my AR
could I reach high pressure signs with the wc844 before I get to the 3100fps?

[sghart]

In short, no.

[Fjold]

So say factory federal ammo is at 3100fps out of my AR
could I reach high pressure signs with the wc844 before I get to the 3100fps?

Every powder is different. Unless you have reliable data charts for the surplus powder, you won't know until you load it. I've seen so much different information on wc844 that it's hard to anticipate what it will do.

[Metal God]

So say factory federal ammo is at 3100fps out of my AR
could I reach high pressure signs with the wc844 before I get to the 3100fps?

Yes

my question is if you load was 25 grains and your getting 3100fps and then you add .5grains to get 25.5 at 3125fps does this mean that for every .5 grains the relative velocity gain will be 25fps?

No ,

No, that is not at all how it works. The system is nonlinear. As you approach maximum pressures, you will see spiking.

Not only that but I'd add that the closer you get to max loads and over the less velocity you get per grain of powder while at the same time your pressure is going WAY up in comparison . "Example" and made up numbers . If a max load is 30,000psi @ 2000fps / 60,000psi will not give you 4000fps . If the gun did not explode you'd likely only get 2800fps . Again this is general example info with NO data to back those numbers .

You can see this happen-ish while working up loads . I often get consistent velocity jumps every .5gr while working with in the min & max of published data . I don't have my notes in front of me but want to say 40fps for every .5gr of IMR 4895 pushing 175gr smk . That 40fps per every .5gr as you hit max loads and beyond starts to drop . How ever just because your velocity is not jumping up in those same consistent large amounts does not mean your pressure isn't rising higher and higher with each charge .

Maybe some one with Quick loads will come along and give a more specific example .

[bigdawg86]

I reloaded some nuke loads for my 357 king cobra and found that accurate no. 9 had velocity drop off at near max loads. Not sure why though.

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[JagerDog]

Within the desired operating range, charge vs. velocity isn't terribly non-linear. Charge vs chamber pressure is quite non-linear.