Does anyone have any load data for a 250 gr cast bullet for 41 mag, using Herco? I've run it up to 8.2 gr, and accuracy started falling off. 8.0 grains was half decent accuracy wise, and yielded 975 fps.
Thanks, Phil
ALLIANT has data for HERCO in the magnum pistol cartridges. Worked excellently in several 41 and 44MAGS for me with cast SWC projectiles. I think your loads need increased to optimum efficiency as you are well under the maximum loads.
Thanks for the response, Will.
I can't find any Herco loads in the current books that I have, and nothing on Alliant's web. I even called them yesterday, and he had nothing on file. I checked my old manuals back to 94, and nothing.
WELL SHIQ !!!
Go check your Lyman manuals because I know i've seen the data in full printed form.
PS: you can also use UNIQUE data and work up from there as HERCO is DISTINCTLY slower burning than Unique, but of the same chemical family/composition.
OKAY got it !!!
From the Lyman Cast Bullet Handbook.
With the Lyman 240gr LFN using HERCO propellent:
starting charge ....8.5 grs starting load
MAX charge ...13.0grs MAX load
I would start at the suggested starting charge and go up from there. It would not surprise me to see you could go to the top charge as HERCO as a most pleasant attitude about top loads in ALL the calibers I tested it in over the years.
Herco has been an EXTREMELY useful powder for me for many years. 12 ga, 20 ga, and 28 ga field loads, and mid-range to near-top-velocity loading in the straightwall magnum revolvers from 32 to 44 plus 45 Colt/Ruger. I go through a lot of it.
A bit of caution might be in order here.
The OP is using a 250 lead bullet.
My Speer #9 Manual shows a max charge of 10.1 Grns when using Herco under a cast 215 Grn gas-checked, LSWC. That is about 30% less powder than Lyman is saying can be used under a 240 lead bullet.....and neither seems to say anything about a 250.
Not arguing about which book is closer to being right. Just sayin' that there's a lot of discrepency between the two and neither is answering the question as posed anyway.
