Comparing 9.3mm designs

LouieLouie
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Joined: Wed May 02, 2012 5:04 pm

Comparing 9.3mm designs

Postby LouieLouie » Mon Nov 19, 2012 12:59 pm

When turning a flatbase bullet around to measure throat length, my new Savage 9.3x62 has roughly .435" of throat. With .305" of neck I tried a couple different designs that would provide support either in the throat or to the bore and still be at the lighter end of the 9.3mm spectrum. I was thinking of taper crimping and that the bore-rider design might be more 'field friendly' w/o exposed lube grooves. Please share your thoughts:

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mtngun
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Re: Comparing 9.3mm designs

Postby mtngun » Tue Nov 20, 2012 12:38 pm

The only way to know which design your gun prefers is to try them both.

The designs that you posted have been edited in a misleading manner. "Rifle Throat Length" is an output, NOT an input. The designs that you posted DO NOT fit a throat length of 0.435".

Ditto for "Length Inside Case."

Inputs are in the upper, baby blue section of the design page. All inputs have a pull down menu.

The bottom half of the design page, with the blue-grey color, is strictly output. There are no pull down menus for the outputs.

For example, if I plug your bore-rider inputs into the program, it spits out "Rifle Throat Length" = 0.15" and "Length Inside Case" = 0.34".

The "Rifle Throat Length" estimate only works for short, sharply tapered throats such as you might find in a lever action. It's not accurate enough for long, gentle throats, and it's totally irrelevant for bore riding bullets.

LouieLouie
Posts: 2
Joined: Wed May 02, 2012 5:04 pm

Re: Comparing 9.3mm designs

Postby LouieLouie » Wed Nov 21, 2012 7:07 am

OK - I was thinking that on the bore-rider I could seat out to the top body band (the DBM allows up to 3.6" COL). I'm trying to find some Cerrosafe locally and cast the chamber before I commit a design. The intent was to design a bullet that was just long enough (.305 neck + .435 throat + .2 ogive) to stand a chance of being reasonably accurate for plinking.

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mtngun
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Re: Comparing 9.3mm designs

Postby mtngun » Wed Nov 21, 2012 8:55 am

LouieLouie wrote:OK - I was thinking that on the bore-rider I could seat out to the top body band (the DBM allows up to 3.6" COL). I'm trying to find some Cerrosafe locally and cast the chamber before I commit a design. The intent was to design a bullet that was just long enough (.305 neck + .435 throat + .2 ogive) to stand a chance of being reasonably accurate for plinking.


A cast rifle bullet wants to be supported at 2 places 1) the nose kissing the rifling, and 2) the base centered in the chamber.

I would not automatically assume that the long throat needs to be filled up. Maybe it does, maybe it doesn't. The important thing is that the nose should kiss the rifling.

The upset slug method is easier and more accurate than Cerrosafe.


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