Quickload pressure limit for 6BRA

[dgeesaman]

Hello all,

I've been shooting 6BRA for about 6 months and recently added Quickload to my toolset.

Taking some load data just below where I'm starting to see pressure signs, I calculate 63000psi. I've gotten 10x firings out of this brass based on loads like this and all is well.
To ensure I'm getting the best possible calculation:
- Weighting factor = 0.4
- Case volume = actual using fired brass and a 21st Century plug
- Bullet measurements using actual weight, overall length, and boat-tail data.
- Shot start pressure = 6000psi (I'm shooting .010 jam)
- Finally I entered my actual powder charge and lowered Ba slightly until the calc. velocity matched actual.

For those playing along at home, this load is 30.7gr of H4895 behind a Roy Hunter 106 moving at 2970fps. Temp was 40F.

So that kind of pressure is more like Dasher than 6BR. But it seems conservative to use the same pressure limit as 6BR. Am I pushing this too hard?

David

 

[Ned Ludd]

What are the primer pockets telling you?

 

[dgeesaman]

Primer pockets are holding size. Peterson brass. BR-4 Primers themselves are also looking good.

 

[rsmithsr50]

6br is 58700
bra would be the same, yes people have been known to shoot higher in custom actions
start pressure in the land is 10825( 3625 jacketed plus 7200 for in the lands)
ba is the burning RATE, not the powder ENERGY.
I adjust energy, Kj/Kg

to each his own

Hello all,

I've been shooting 6BRA for about 6 months and recently added Quickload to my toolset.

Taking some load data just below where I'm starting to see pressure signs, I calculate 63000psi. I've gotten 10x firings out of this brass based on loads like this and all is well.
To ensure I'm getting the best possible calculation:
- Weighting factor = 0.4
- Case volume = actual using fired brass and a 21st Century plug
- Bullet measurements using actual weight, overall length, and boat-tail data.
- Shot start pressure = 6000psi (I'm shooting .010 jam)
- Finally I entered my actual powder charge and lowered Ba slightly until the calc. velocity matched actual.

For those playing along at home, this load is 30.7gr of H4895 behind a Roy Hunter 106 moving at 2970fps. Temp was 40F.

So that kind of pressure is more like Dasher than 6BR. But it seems conservative to use the same pressure limit as 6BR. Am I pushing this too hard?

David

 

[dmoran]

6br is 58700
bra would be the same, yes people have been known to shoot higher in custom actions
start pressure in the land is 10825( 3625 jacketed plus 7200 for in the lands)
ba is the burning RATE, not the powder ENERGY.
I adjust energy, Kj/Kg

to each his own

And in ACTUALITY, there is no freaking way possible that there is a 10825-psi increase from IN the lands to OFF, or any where near that much. Plus, when compared to actual pressure tests, and when you get done adjusting QL to match the actual pressures, the velocity will typically be a mile off (and/or visa versa). With that all said, I suggest to put little faith in the accuracy of QL to predict actual peak pressures, or to predict pressure & velocity together in tandem accurately.

 

[dgeesaman]

6br is 58700
bra would be the same, yes people have been known to shoot higher in custom actions
start pressure in the land is 10825( 3625 jacketed plus 7200 for in the lands)
ba is the burning RATE, not the powder ENERGY.
I adjust energy, Kj/Kg

to each his own

Ok so running my H4895 load data that way, I needed to lower KJ/Kg to match velocity, and then the peak pressure shot up to 68300 psi(!!). That seems unrealistically high.

And in ACTUALITY, there is no freaking way possible that there is a 10825-psi increase from IN the lands to OFF, or any where near that much. Plus, when compared to actual pressure tests, and when you get done adjusting QL to match the actual pressures, the velocity will typically be a mile off (and/or visa versa). With that all said, I suggest to put little faith in the accuracy of QL to predict actual peak pressures, or to predict pressure & velocity together in tandem accurately.

I guess I figured that if I could take a known load and work out a bunch of the inputs, I might be able to compare various powders and similar bullets while keeping everything else the same. But if the peak pressure is +/- 10% or is to be mostly ignored, I don't see the point of the exercise.

 

[dmoran]

..... I don't see the point of the exercise.

That is why soon after buying a pressure trace system, I stopped using QL except for anything but basic load data, or bought any of the updated versions for it since 2004.

 

[rsmithsr50]

your OPINON does not agree with the INSTRUCTIONS in the quickload software.
having said that, I understand that ql is a tool, and only as good as the user.

And in ACTUALITY, there is no freaking way possible that there is a 10825-psi increase from IN the lands to OFF, or any where near that much. Plus, when compared to actual pressure tests, and when you get done adjusting QL to match the actual pressures, the velocity will typically be a mile off (and/or visa versa). With that all said, I suggest to put little faith in the accuracy of QL to predict actual peak pressures, or to predict pressure & velocity together in tandem accurately.

 

[rsmithsr50]

ya gotta keep good records on each cartridge/rifle/powder.

or buy a pressure trace system.
how much Donovan ?
and is it practical to use on an as is rifle ?

Ok so running my H4895 load data that way, I needed to lower KJ/Kg to match velocity, and then the peak pressure shot up to 68300 psi(!!). That seems unrealistically high.



I guess I figured that if I could take a known load and work out a bunch of the inputs, I might be able to compare various powders and similar bullets while keeping everything else the same. But if the peak pressure is +/- 10% or is to be mostly ignored, I don't see the point of the exercise.

 

[dmoran]

your OPINON does not agree with the INSTRUCTIONS in the quickload software.
having said that, I understand that ql is a tool, and only as good as the user.

Well have you ever seen a 10,825-psi spike in pressure from say .015"-IN to say .015"-OFF ?

Your chronograph can yield a real good prediction to how much pressure indifference, by computing the percentage of velocity indifference, will be a very close percentage to actual change in pressure as well (pressure+velocity fallow each other very linearly).

 

[dbduff]

Hello all,

I've been shooting 6BRA for about 6 months and recently added Quickload to my toolset.

Taking some load data just below where I'm starting to see pressure signs, I calculate 63000psi. I've gotten 10x firings out of this brass based on loads like this and all is well.
To ensure I'm getting the best possible calculation:
- Weighting factor = 0.4
- Case volume = actual using fired brass and a 21st Century plug
- Bullet measurements using actual weight, overall length, and boat-tail data.
- Shot start pressure = 6000psi (I'm shooting .010 jam)
- Finally I entered my actual powder charge and lowered Ba slightly until the calc. velocity matched actual.

For those playing along at home, this load is 30.7gr of H4895 behind a Roy Hunter 106 moving at 2970fps. Temp was 40F.

So that kind of pressure is more like Dasher than 6BR. But it seems conservative to use the same pressure limit as 6BR. Am I pushing this too hard?

David

 

[dbduff]

Have you checked water capacity for differences between Peterson and Lapua brass? I'v found Peterson has less capacity in SRP 243 than Lapua. Have not tried Peterson 6 Norma BR. If data is for Lapua, Peterson may be different. Primer pockets will tell the story. I'm running a 6brdx (6ai) H 4895, BR 4s, 105 Barts, touching. Vel 2860. Lapua hydroformed. No problems, turned necks.

 

[Murray Brook]

@dmoran With your pressure trace system have you ever tried ( to determine) the pressure difference from, say , a slight jam or .010 jam to say .020 off. I'd be curious to see what the difference is.

 

[dmoran]

@dmoran With your pressure trace system have you ever tried ( to determine) the pressure difference from, say , a slight jam or .010 jam to say .020 off. I'd be curious to see what the difference is.

To many different effecting scenario's to be a common amount, but likely no less then 1000-psi to likely no more then 2500-psi.

 

[rsmithsr50]

the reason I start single feed load development at the lands is so pressure is at its peak and I can work down.
yes I use pressure velocity all the time

Well have you ever seen a 10,825-psi spike in pressure from say .015"-IN to say .015"-OFF ?

Your chronograph can yield a real good prediction to how much pressure indifference, by computing the percentage of velocity indifference, will be a very close percentage to actual change in pressure as well (pressure/velocity fallow each other very linearly).

 

[dgeesaman]

Have you checked water capacity for differences between Peterson and Lapua brass? I'v found Peterson has less capacity in SRP 243 than Lapua.

Yes I've measured capacity in fully formed Peterson brass. I have not measured Lapua for comparison.