6mm Rem revisted

[Brithunter]

Hi Gitano,

  Reading your data for IMR 4831 and comparing it to what I tried earlier in my rifle I see that my loads were quite some way from the OBT as the highest charge I tried was 45.3 grains with the 100 grain Hornady. I shall be going to the range on Sunday with some suitable test loads.

[gitano]

I shall be going to the range on Sunday with some suitable test loads.

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I wait for the results with bait on my breath... :D
 
Subsonic,
Are you sending measurements?
 
Paul

[Brithunter]

Ahhh Gitano,

      As the charges computed by Quickload are quite a bit higher than the loading mauals suggested I loaded seven cartridges with 46.8 grains of IMR 4831 with the Hornady 100 grain Spire point loaded to 3.018" and using a CCI 250 magnum primer. Accuracy is not so hot but the load is too hot with severly cratered primers. I tested them on the field rather than wait until tomorrow after a 40 mile drive. I will drop the load to 45.5 grains and try that.

      Meanwhile I will continue with testing the 87 grain loads with Varget as I already have a batch loaded ready for tomorrow this is the one which sput three shots touching at the range last week so shows promise.

[subsonic]

Subsonic,
Are you sending measurements?
 
Paul

I will be. Just have to find time to get my butt down in the basement and measure.
 
This morning it was change the brakes, rotate the tires, oil change, etc for the wife's car.
 
Then I re-engineered a $25 air rifle from Cummins Tools and sighted it in (after losing a tiny, very important ball bearing in it that is now a piece of #8 shot...) and had a small war with some squirrels who've eaten 1/2 the corn we planted.
Now I'm "cooling off" and "hydrating"

[gitano]

OK...
 
From now on, any loads I provide as the result of QL calculations need to be double-checked by those intending to use them, and then back by me. In fact, I will print out hte QL calculation page, so everyone can have a look at all the values for all the variables.
 
Recalculating the I4831 OBT charges for the Hornady 100-grain bullet seated for a COAL of 3.018" gives me numbers no where near those posted in the earlier post. The 48.3-grain charge NOW says the pressure is at just over 64 kPSI, just under the SAAMI max of 65,000. Regardless of being off, that's bad.
 
I can't get QL to give me the numbers I posted above, so I can't figure out what I did wrong.
 
Double-checking everything, twice, I get the following numbers:
 
Barrel length - 23 11/16ths = 23.6875"
COAL - 3.018"
Bullet - Hornady 100-grain Spitzer - Part Number 2450
Powder - I4831
Charge - 44.87 grains
% of case capacity - 94.5%
Estimated Max chamber pressure - 54,044 PSI
Bullet exit time - 1.212 mSec
Muzzle velocity - 3012 f/s
 
A charge of 3% less is:
43.52 grains
% of case capacity - 91.5%
Estimated Max chamber pressure - 49,445 PSI
 
Here's the QL calculation screen capture

 
 
Now I see the error... The charge for the 1.088 mSec node for the 100-grain bullet with COL of 3.018" is 48.3 grains. The estimated chamber pressure is 68,090 PSI. The 46.8-grain charges you tested are estimated to generate a max chamber pressure of 61,333 PSI.
 
The 3% down charge for the 1.088 mSec node is the 46.85 grains you tested. I think the error was that I was looking at the 1.088 mSec node charges and thought I was looking at the 1.212 node charges.
 
This has bothered me greatly. I have purchased a piece of software that allows me to capture the QL screen and save it as a jpg. I will not provide any more load numbers without providing the QL calculation page so that everyone can review the numbers and make sure they make sense.
 
My sincere apologies BH.
 
Paul

[Brithunter]

Ahhh I did wonder hence the little test before going to the range as you talked about the 43.0 grain load being very close to ideal :) .


However as the rifle is a commercial M98 action it was not a real problem I will print your reply off later. Just having a cuppa before getting all ready to go over to the range. I was woken by the wind driven rain hammering on the roof of the Mobile home but it's eased off now and is brightening up some. Let's hope the wind stays down.


Even with that overload the case is still not full you know if you shake the loaded cartridge next to your ear you can hear the powder rattle back and forth slightly in the case.

  Edit:-  I think I can find the time before leaving to load a few with that 43.5 grain load.