375 Flanged Magnum

[Kevin Peacocke]

Hi all, please can someone advise what charge I should use of Vihtavhouri N565 for
375 Fl
300 grain Woodleigh bullet
24" barrel
25 degrees C

Many thanks

 

[Kevin Peacocke]

Hi all, please can someone advise what charge I should use of Vihtavhouri N565 for
375 Fl
300 grain Woodleigh bullet
24" barrel
25 degrees C

Many thanks

Sorry, the target velocity is 2400fps.

 

[frog stealer]

XXL Reloading doesn’t list N565 for 300 grain bullets, neither does the Woodleigh manual. I can run it in quickload if you like, but I think it might be to slow to attain 2400 before running out of case capacity.

 

[frog stealer]

I stand corrected, looks like around 82 grain will get you there with light compression.

Of course, work up slowly and look for pressure signs, this is a software approximation.

 

[Kevin Peacocke]

I stand corrected, looks like around 82 grain will get you there with light compression.

Of course, work up slowly and look for pressure signs, this is a software approximation.

View attachment 519842

Thank you @frogstealer, that helps greatly.

 

[Desperatezulu]

Hi Kevin,

I ran it through GRT and got a somewhat different answer to Frog Stealer. I note that he's used a 26" barrel. The key parameter in these simulations is having a precise case capacity -> GRT default is 94.4gr H2O.
To be on the safe side, I would advise measuring the H2O capacity of a fired case (with the fired primer still in) - once we have this value, a more robust starting load can be given.

GRT suggests 80.8gr V565 for 2400f/s at the muzzle for 24" barrel and 94.4gr H2O case capacity, giving a peak pressure of 37,800psi (CIP max allowed pressure is 47,000 psi - so you're well away from the red zone provided the case capacity is more or less in line with my assumption). I assumed the exact same bullet as FS.

I don't think the suggestions are world's apart but it does show that accurate input data is quite important

As an aside, N565 is not an optimal powder for this round as the burn rate is a bit slow - only around 84% is calculated to be burnt by the time the bullet exits the muzzle. This means 2 things - 1. that there will be impressive muzzle flash and 2. the inconsistency of the powder burn may mean a significant deviation between the simulation and reality. I appreciate that you may not have much of a powder selection in Zim, so you have to do what you must.

If you can give us the actual case capacity and the chrono'd MV from a starting load, then the software will help you get much closer.

 

[Desperatezulu]

Perhaps some useful info here:
From Norma

I see MRP powder also has quite a low burnt propellant percentage in the Fl Mag so maybe my concern is misplaced. I have a lot of faith in Norma's info as a general rule.

 

[Kevin Peacocke]

Perhaps some useful info here:
From Norma

I see MRP powder also has quite a low burnt propellant percentage in the Fl Mag so maybe my concern is misplaced. I have a lot of faith in Norma's info as a general rule.

Hi DZ, thank you so much for this information. I will load with 80.8 grains on Saturday and chrono it, will report back to you. Kevin

 

[F. Vaccaro]

How much below the .375 H&H Mag. is the .375 Flanged?
can .375 H&H starting loads be used?
please keep us informed Kevin I am interested too!

 

[KJE81]

How much below the .375 H&H Mag. is the .375 Flanged?
can .375 H&H starting loads be used?
please keep us informed Kevin I am interested too!

When I changed riflescope on my doublerifle the regulation was affected so I tried more then ten different powders and several loads were for the .375H&H from Vihtavuori and Norma load data. I did not had any pressure signs at min loads and a couple of grains up but after that it started to be hard to open.

So I assume that judging from my experience the min loads are safe to try with the usual caveats about what works in one gun does not necessarily work in all guns etc.

 

[dchamp]

 

[dchamp]

 

[Desperatezulu]

How much below the .375 H&H Mag. is the .375 Flanged?

The default capacity or volume of the H&H Mag case is actually slightly smaller than the Mag Flanged - the big difference is in the CIP max pressure. The H&H Mag is 62,000 psi (which is surprisingly high for a cartridge of its vintage) and the Mag Flanged Pmax is only 47,000 psi.

can .375 H&H starting loads be used?

Nope, a starting load for the H&H Mag might be in the low 40,000s psi which would already be raising eyebrows on the Flanged. So the short answer is that the starting loads should be a fair bit lower for the Flanged, all else being equal.

 

[F. Vaccaro]

Thanks, I’m keeping tuned here.

 

[Frank375]

View attachment 520117

What does C and T after the charge mean ?

 

[Frank375]

What does C and T after the charge mean ?

I suppose C means compressed but what does T represent?

 

[frog stealer]

It’s Quickload’s way of showing specific powders are copper reducing or temp insensitive.

 

[Frank375]

Thanks.

 

[Desperatezulu]

Hi DZ, thank you so much for this information. I will load with 80.8 grains on Saturday and chrono it, will report back to you. Kevin

How did it go?

 

[Kevin Peacocke]

How did it go?

Hi DZ, didn't get that far yet, perhaps this Saturday.