Secant: what does this mean

glt41
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Joined: Wed Feb 20, 2008 8:29 pm

Secant: what does this mean

Postby glt41 » Wed Feb 20, 2008 8:37 pm

Hi Dan --Need definiation what is SEC on the design page? I am getting ready to send you my order but still fiddling which means I have not really made up my mind :?: --might just order a Keith --what is the SEC and its relationship to the others such as TAN.

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mtngun
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Re: Need to know what does this mean

Postby mtngun » Thu Feb 21, 2008 5:23 am

A tangential ogive is tangent to the front band (or tangential to the bore riding section, on a bore riding nose.
Image

My secant ogive doubles that radius. In theory, a secant ogive could be any radius greater than a tangential ogive, but I chose 2X because it is simple to program.
Image

Secants are used on jacketed bullets because they improve the ballistic coefficient very slightly. Hornady spire points are an example of a secant ogive.

CB shooters usually don't care about ballistic coefficient. We do care about chambering and how far the bullet has to jump until it contacts the rifling (or the revolver throat). The secant makes the crimp-to-throat distance a little shorter and a little easier to predict. For that reason, a secant is sometimes used in short-throated firearms like Freedom Arms revolvers and some leverguns.

Original LBT designs made by Veral were more or less tangential. However, "imitation" LBT bullets are sometimes secants, probably because the secant is more likely to chamber in tight-throated guns..

glt41
Posts: 3
Joined: Wed Feb 20, 2008 8:29 pm

Re: Secant: what does this mean

Postby glt41 » Thu Feb 21, 2008 10:27 am

Thanks for the answer --I am not new -- I was GLynn41 but had log in problems so I reregistered-- my fault and a little alck of patience


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