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Topic: Help with Vihtavuori N550, 142gr Accubond Long Range (Read 869 times) previous topic - next topic

Help with Vihtavuori N550, 142gr Accubond Long Range

Hi there

Our suppliers in South Africa are out of Somchem S365 so I want to try Vihtavuori N550.

Could anyone with Quickload perhaps tell me what the maximum load is for: Howa 6.5 CM Bull Barrel, 142gr Accubond Long Range, Vihtavuori N550, Lapua Brass?

Any advice will be appreciated as this is my first load for the Creedmoor so a little in the dark!!

I have read quite a few post where the Vihtavuori data is way low resulting in low pressure blackening in cases. So Vihtavuori states max load on a 140gr @ 38.3 but on posts I have read guys are hitting a sweet spot @ 41-42 grns.

Thanks
Jim

Re: Help with Vihtavuori N550, 142gr Accubond Long Range

Reply #1
Jim,

I am just starting load development for a new rifle, and I am also very new to QuickLoad. I have already run into the discrepancy that you describe with N550 and 140 g. bullets, and I'm not sure which source to believe, or how to rationally rectify them, so I am proceeding with QuickLoad with caution. But I will tell you my first experience shooting NOS 140 Ballistic Tips out of my 22", 1:8" Lilja barrel, and that may give you an idea of what to do.

When I loaded Vihtavuori's max 38.3 g. number into my QuickLoad scenario, it showed pressure well below the yellow caution zone at 43,181 psi, and muzzle velocity at 2,484 fps. 39.5 g. input brought pressure just up to the bottom of the yellow zone at 47,136 psi, so I loaded an initial 1-shot string from 37.1 to 39.5 g. I measured muzzle velocities with a MagnetoSpeed chronograph, and the MagnetoSpeed results fit the QuickLoad model very closely with the default burn rate of .4650. My 39.5 maximum load yielded 2,565 fps (measured) vs. 2,557 (predicted), while my 38.3 g. load yielded 2,510 fps (measured) vs 2,484 (predicted). I tweaked the burn rate to .4678 to match my max load, and projected a new max load of 43.3 g., with 62,671 psi (predicted), and 2,791 fps (predicted).

I will be loading this new string today and probably testing it next week. Sorry I can't give you a QuickLoad number to fit your rifle and load particulars (too risky), but I hope this helps confirm your suspicion.

Re: Help with Vihtavuori N550, 142gr Accubond Long Range

Reply #2
Jim

Hornady lists 41.3 grains 2750 fps as max for 140-143 grain bullets.
RPR 6.5 Creedmoor
Bergara 6 Creedmoor

Re: Help with Vihtavuori N550, 142gr Accubond Long Range

Reply #3
Thanks,finally got round to finalizing my load.
Sweet spot found is 40,7 grains with 2745 ft/sec. I started too low at 36.5 which only delivered 2550ft/s.

Re: Help with Vihtavuori N550, 142gr Accubond Long Range

Reply #4
According to QL, you can go up to 43 grains of N550, of course, checking for any of the pressure signs on your way up.


Re: Help with Vihtavuori N550, 142gr Accubond Long Range

Reply #5
JB26 have u had success loading accubond 142 with 365?Been fireforming and loading with 341 with moderate results so far.
Grateful for everything I got and living everyday to the fullest in the outdoors whenever I get the opportunity.

Re: Help with Vihtavuori N550, 142gr Accubond Long Range

Reply #6
I am yet to find S365 so have been focusing on N550. I went to a 40.7gr, 40.9gr, 41.1gr and 41.3gr ladder. High pressure signs so and 2820ft/sec on 40.9.

My test before that was from 33.5 to 38. I found a sweet spot at 36.5 gr but with 2550ft/sec.

I now need to find a load between 38 and 40 which will give me 2710ft/sec or there abouts.

It is proving to be a long process compared to my load development for my other calibers...

Input is welcomed
Thanks
Jim
South Africa

 

Re: Help with Vihtavuori N550, 142gr Accubond Long Range

Reply #7
Hi Jim.been off the forum and off creedmor for a while.thanks for the reply.I am gonna be running some Quikload numbers and been trying to get my hands on N550.once I’ve run some shots through I will let you know.thanks
Grateful for everything I got and living everyday to the fullest in the outdoors whenever I get the opportunity.