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October 15, 2018, 06:49 PM
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#1 |
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Senior Member
Join Date: June 17, 2010
Location: Virginia
Posts: 6,885
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38-55 HiWall -- Heavy bullets -- Black Powder
For those who think 18:1 is too slow for BP
  325gr/Accurate Molds (another one ordered on Saturday/Arrived in Thursday/Cast on Friday/Shot on Saturday)  
Last edited by mehavey; October 15, 2018 at 06:58 PM. |
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October 15, 2018, 06:51 PM
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#2 |
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Staff
Join Date: March 4, 2005
Location: Ohio
Posts: 21,061
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Nice group! How long is that bullet?
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Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle |
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October 15, 2018, 07:00 PM
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#3 |
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Senior Member
Join Date: June 17, 2010
Location: Virginia
Posts: 6,885
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 1.18" post: I lied. QL predicted 1,155fps from an earlier/lower trial from which I'd tweaked the Miller K-factor for Swiss 1.5 LABRADAR showed actual to be 1,159fps |
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October 15, 2018, 07:44 PM
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#4 |
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Staff
Join Date: March 4, 2005
Location: Ohio
Posts: 21,061
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Stability factor of over 1.7. High end of optimal, so stability should be just fine and looks like it is!
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Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle |
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October 16, 2018, 08:37 AM
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#5 |
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Senior Member
Join Date: September 9, 2009
Location: arkansas
Posts: 218
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Nice!
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October 16, 2018, 02:21 PM
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#6 |
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Senior Member
Join Date: February 13, 2002
Location: Canada
Posts: 12,453
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The twist is about the bullet weight. Not the propellant. 1 in 18 is apparently common for the .38-55 though. Who told you it wasn't?
Mind you, the BP cartridge guys argue about twists too. http://www.bpcr.net/forum/viewtopic.php?t=2369 https://www.assra.com/cgi-bin/yabb/Y...num=1202346186
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October 16, 2018, 05:27 PM
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#7 | |
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Senior Member
Join Date: June 17, 2010
Location: Virginia
Posts: 6,885
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Quote:
Black Powder --> ~ speed Miller's is all about length/diameter and speed re twist. I one looks at "The Internet" one finds all sorts of opinions as to 38-55 heavy weight reqm'ts and performance... ranging from 12:1, 14:1, 18:1 ... and all sorts of "that's too slow a twist" for BP speeds. In fact, straight Greenhill's likes a 14 twist for those lengths/diameters/speeds Still, things are a bit more complex that straight Greenhill. So like UncleNick, I went to both JBM & Berger w/ real data on real bullet and real lower-bound speeds and plugged it in for an 18 twist:  . . . and it appears that theory and actual shooting data do overlap. . Last edited by mehavey; October 16, 2018 at 10:10 PM. |
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October 16, 2018, 06:32 PM
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#8 |
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Senior Member
Join Date: October 25, 2001
Location: Alabama
Posts: 18,535
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My .38-55 has a 15 twist by rebore from .32-40.
It does well with the 336 gr Lyman "Mini-Snover." I load 40.6 gr Swiss 1 1/2 because that gives compression the thickness of the over powder card wad with the top lube groove just covered. Won't knock down all the 500 metre rams I hit, though. |
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