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View Full Version : Quick Load 45-70 420 grain hard cast LBT H4198



pitchfire
08-11-2017, 04:04 PM
I loaded up some Cast Performance 405 grain hard cast WLN GC boolits: http://www.grizzlycartridge.com/index.php?app=ecom&ns=prodshow&ref=CP458405A&sid=0bh9j55wh7j2xc70jba72d21ta0x388d using H4198 WLR primers and new Starline cases trimmed and prepped for my 45-70 High Wall. I started at 46 grains and worked my way up to 50 (53 grains is max for the High Wall but slightly compressed with my trimmed cases). The rifle I have is a 6 lb cavalry carbine with a slip on recoil pad that I used after a while (recoil got rather old after 20 rounds or so).

After 12 rounds to verify safe load development, from 46-50 grains (1800-2000fps approx) I fired 13 more at 46 grains as I was sighting in my scope and after it leaded up the POI changed. I took one shot at an 8" target at 100 yards and was on target off hand so I was happy for the moment.

So I wound up with more leading than I liked and spent a lot of time cleaning with Shooters Choice Lead Remover, Boretech Eliminator, copper from a O Cedar brand chore boy (all copper with good sharp edges), a brush, patches, Breakfree CLP and patience. The barrel is as clean as it is going to get now and I am switching to Cast Performance 420gr WLN GC boolits so I can get more lube in the barrel. I am also using the crimp groove as a lube groove and seating to just above the crimp groove (I'm not crimping the boolits as I am using a High Wall/single shot and enough neck tension to securely hold the boolit in place).

The barrel was cleaned well and was smooth before firing (no rough spots) and dry patched before heading to the range. The bore diameter at the throat is .457" (haven't yet pushed all the way through the muzzle) and the boolits are sized at .459".

I know the velocity is up there, but not too extreme. I did not pay any attention to see if I was getting a lube star but will in the future. The leading was most persistent near the muzzle (didn't notice or could not see it well near the throat) so I'm leaning towards lube (not enough) as the culprit.

So I want to load up some 420 grain boolits I have because they will have a good mm more lube exposed to the barrel than the 405 grain boolits had. http://www.grizzlycartridge.com/index.php?app=ecom&ns=prodshow&ref=CP458420A&sid=0bh9j55wh7j2xc70jba72d21ta0x388d

As to why I want to, certainly not for bench rest work, but for a few shots standing it isn't bad without the recoil pad, and we do have big bears here (in Alaska) and I like the idea of doing this with hard cast lead: https://youtu.be/kbQGTZ3jYzU?t=156

Finding good load data for odd sizes is somewhat difficult but extrapolating from available data (above and below) for the same powder gets me a reasonable start load of 45 grains and a max around 52 grains (though I am not headed there). Start loads for the data I have from Hodgdon run 31,800CUP and Max loads are at 49,100CUP (mostly because the powder would be compressed beyond that point, sooner in my cases otherwise 50,000CUP is the threshold).

I would greatly appreciate it if anybody could run Quickload and see how many grains of H4198 it takes to generate 32,000CUP to verify my start load of 46 grains and how many grains to get to 50,000CUP (though I never intend on going there) so I can verify what a safe max looks like (which should be around 51 grains though I suspect that max is more limited by the case volume than by pressure and I am not going to load anything compressed). I am going to verify, at my seating depth how much powder will fit after I weight sort the boolits to find the heaviest. I am using H4198, Cast Performance 420 WLN GC, WLR primers, Starline cases trimmed to 2.098" and an COAL of 2.561".

Thank you all who made it this far through my long winded post! 201700

Tatume
08-11-2017, 07:38 PM
Take a look at:

http://www.hodgdonreloading.com/

They get to 49,100 CUP with a 400 grain jacketed bullet. I doubt you'll get that high with a cast bullet.

Take care, Tom

pitchfire
08-11-2017, 09:19 PM
Thanks. That's what I have been basing my loading around combined with other sources like Beartooth Bullets load data for some larger bullets. I tried loading up some 420's after weight sorting them and found that at my trim length I have to stay under 50 grains to stay away from a compressed load (So I don't think it is possible to go over pressure without compressing the charge). I contacted Hogdgon to see what they think of compressed loads for this application after reading their blurb: http://www.hodgdonreloading.com/reloading-education/reloading-beginners/compressed-loads "A full case, or lightly compressed charge is an ideal condition for creating loads with the most uniform velocities and pressures, and oftentimes, producing top accuracy..."