Ian
Notorious member
I need everyone's help and input here. Following Fiver's "design and alloy" thread that was intended to get the brain juice flowing among the high-velocity crowd, I'd like to compose for our readers a reference article for the read-only section regarding specific properties of ternary Pb/Sb/Sn alloy as it relates to HV cast shooting in rifles (and possibly zinc and copper-enhanced alloy too, maybe a separate one for those though). I'll compose the article here in the OP and keep editing it with additional input from members who will be credited for their contributions. If you have your own ideas along these lines, write it up and post it here.
The items I'd specifically like to address in the article, subject to additional input, are:
#1 Philosophy of launch: The particular alloy characteristics that are needed to achieve a straight start in the barrel, considering various rifle throat shapes and bullet styles. This will include how to work with various lube groove designs, nose bump and when it's needed, neck clearance and how to work with it, tapered and 2D bullets and the differences alloy makes with each.
#2 Alloy composition: How to achieve, through blending and heat treating, the characteristics needed in #1. Details of what each alloy component does so that the reader can better understand when they might want to try using more tin, or lower antimony and higher heat treat, etc.
#3 Leading edge failure: Discussion of the secondary HV challenge, which is constructing an alloy which will withstand high surface speeds and the force of standard rifling twist rates without experiencing abrasion failure. This excludes the companion subject of rifling condition/quality, which has been well-covered by others.
I'm looking for input with specific, empirical examples of what works as well as what doesn't, so the "why" can be inferred or offered as reasonable explanation. .22 to .35 caliber seems to be the area of interest, with 22 and 30 seeming to get the most attention on this board. If you have a quick example that can be inserted into the article then please feel free to throw it out there, particularly if it will demonstrate the effect that a specific alloy change or bullet shape made to improve groups. I'll start pecking away at a composition as I have time and inspiration, right here, below.
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The items I'd specifically like to address in the article, subject to additional input, are:
#1 Philosophy of launch: The particular alloy characteristics that are needed to achieve a straight start in the barrel, considering various rifle throat shapes and bullet styles. This will include how to work with various lube groove designs, nose bump and when it's needed, neck clearance and how to work with it, tapered and 2D bullets and the differences alloy makes with each.
#2 Alloy composition: How to achieve, through blending and heat treating, the characteristics needed in #1. Details of what each alloy component does so that the reader can better understand when they might want to try using more tin, or lower antimony and higher heat treat, etc.
#3 Leading edge failure: Discussion of the secondary HV challenge, which is constructing an alloy which will withstand high surface speeds and the force of standard rifling twist rates without experiencing abrasion failure. This excludes the companion subject of rifling condition/quality, which has been well-covered by others.
I'm looking for input with specific, empirical examples of what works as well as what doesn't, so the "why" can be inferred or offered as reasonable explanation. .22 to .35 caliber seems to be the area of interest, with 22 and 30 seeming to get the most attention on this board. If you have a quick example that can be inserted into the article then please feel free to throw it out there, particularly if it will demonstrate the effect that a specific alloy change or bullet shape made to improve groups. I'll start pecking away at a composition as I have time and inspiration, right here, below.
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