Forums
New posts
Search forums
What's new
Articles
Latest reviews
Author list
Classifieds
Log in
Register
What's new
Search
Search
Search titles and first posts only
Search titles only
By:
New posts
Search forums
Menu
Log in
Register
Install the app
Install
Forums
Rifles, Reloading, Optics, Equipment
Reloading
Advice on bullet seating depth Berger 95 grain hybrid
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Message
<blockquote data-quote="merbeau" data-source="post: 776933" data-attributes="member: 38494"><p><span style="color: black"><span style="font-family: 'Times New Roman'">Hi Westcliffe01</span></span></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">The bullet I have mics to 1.070 inches which is the classic hunter. The box says for 1:10 twist or shorter. I did not purchase the VLD because of the stability issue. I used several tools from </span></span></p><p> </p><p><span style="color: black"><a href="http://www.jbmballistics.com/ballistics/calculators/calculators.shtml" target="_blank"><span style="font-family: 'Times New Roman'"><span style="font-family: 'Times New Roman'"><span style="color: #0000ff">http://www.jbmballistics.com/ballistics/calculators/calculators.shtml</span></span></span></a> </span></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">t</span></span><span style="color: black"><span style="font-family: 'Times New Roman'">o estimate the Miller Stability Coefficient and this bullet for my twist rate, elevation and mean temperature had a predicted value of 1.43 which according to the literature any number from 1.3 to 2.0 is acceptable. I understand the US Military uses a value from 1.5 to 2.0 for their work.</span></span></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">The area I live has a quite a few windy days so ballistic coefficient is important to me. I did a sensitivity analysis using the above web site for the published G1 value of 0.427 as compared to a much lighter bullet and there was a factor of 2 for bullet drop versus a factor of 4 for deflection. That is my rationale for choosing this bullet. </span></span></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">You quoted in your response</span></span></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">'I am interested in seating my bullets longer, mainly to improve case capacity and reduce peak pressure. I do not want to be jamming my bullets into the lands, because that is exactly where it becomes imperative to have special bullet seaters which pick up the position of the bullet closer to the tangent point so that land engagement becomes more consistent.'</span></span></p><p> </p><p><span style="font-family: 'Times New Roman'"><span style="color: black">That was my rationale. For volume I used the water technique and found a mean of 52.0 grains with a range of 52.2 to 52.3 grains which makes me wonder just how important this is for smaller cases. </span><span style="color: black"><span style="font-family: 'Calibri'">To obtain the volume occupied by the bullet I added the case length (2.032) and bullet length (1.07) then subtracted the overall COL (2.695) which is 0.407 inches for bullet seating. I used a blank case and cut two slits in the side inserted a bullet and closed the bolt slowly. I then removed the cartridge and measured the length and checked to make sure it would function in my magazine. There were light marks on the bullet and I used a bullet comparator to obtain a just touching the lands seating depth.</span></span></span></p><p> </p><p><span style="color: black"><span style="font-family: 'Calibri'"><span style="font-family: 'Times New Roman'">Next calculate the area of the bullet's cross section. For a .243 diameter bullet, that is (0.2432 ÷ 4) x 3.1416 = 0.0464 square inches. Multiply that area by the seating depth gives you the volume 0.0188 of the case occupied by the bullet, but it is in cubic inches. To convert cubic inches to grains of water, multiply by 252.8 grains of water per cubic inch which is 4.774 grains. Then subtract from case volume 52.0 – 4.774 = 47.23 grains. This a little off because the Berger bullet is a boat tail. I assume this is the maximum capacity before a compressed load is obtained. And from the literature at least 80% case capacity is necessary with powder so the minimum charge would be 47 x .8 or 38 grains. </span></span></span></p><p> </p><p>Robert</p></blockquote><p></p>
[QUOTE="merbeau, post: 776933, member: 38494"] [COLOR=black][FONT=Times New Roman]Hi Westcliffe01[/FONT][/COLOR] [COLOR=black][FONT=Times New Roman][/FONT][/COLOR] [COLOR=black][FONT=Times New Roman]The bullet I have mics to 1.070 inches which is the classic hunter. The box says for 1:10 twist or shorter. I did not purchase the VLD because of the stability issue. I used several tools from [/FONT][/COLOR] [COLOR=black][/COLOR] [COLOR=black][URL="http://www.jbmballistics.com/ballistics/calculators/calculators.shtml"][FONT=Times New Roman][FONT=Times New Roman][COLOR=#0000ff]http://www.jbmballistics.com/ballistics/calculators/calculators.shtml[/COLOR][/FONT][/FONT][/URL][FONT=Times New Roman] [/FONT][/COLOR] [COLOR=black][FONT=Times New Roman][/FONT][/COLOR] [COLOR=black][FONT=Times New Roman]t[/FONT][/COLOR][COLOR=black][FONT=Times New Roman]o estimate the Miller Stability Coefficient and this bullet for my twist rate, elevation and mean temperature had a predicted value of 1.43 which according to the literature any number from 1.3 to 2.0 is acceptable. I understand the US Military uses a value from 1.5 to 2.0 for their work.[/FONT][/COLOR] [COLOR=black][FONT=Times New Roman][/FONT][/COLOR] [COLOR=black][FONT=Times New Roman]The area I live has a quite a few windy days so ballistic coefficient is important to me. I did a sensitivity analysis using the above web site for the published G1 value of 0.427 as compared to a much lighter bullet and there was a factor of 2 for bullet drop versus a factor of 4 for deflection. That is my rationale for choosing this bullet. [/FONT][/COLOR] [COLOR=black][FONT=Times New Roman][/FONT][/COLOR] [COLOR=black][FONT=Times New Roman]You quoted in your response[/FONT][/COLOR] [COLOR=black][FONT=Times New Roman][/FONT][/COLOR] [COLOR=black][FONT=Times New Roman]'I am interested in seating my bullets longer, mainly to improve case capacity and reduce peak pressure. I do not want to be jamming my bullets into the lands, because that is exactly where it becomes imperative to have special bullet seaters which pick up the position of the bullet closer to the tangent point so that land engagement becomes more consistent.'[/FONT][/COLOR] [FONT=Times New Roman][COLOR=black][/COLOR][/FONT] [FONT=Times New Roman][COLOR=black]That was my rationale. For volume I used the water technique and found a mean of 52.0 grains with a range of 52.2 to 52.3 grains which makes me wonder just how important this is for smaller cases. [/COLOR][COLOR=black][FONT=Calibri]To obtain the volume occupied by the bullet I added the case length (2.032) and bullet length (1.07) then subtracted the overall COL (2.695) which is 0.407 inches for bullet seating. I used a blank case and cut two slits in the side inserted a bullet and closed the bolt slowly. I then removed the cartridge and measured the length and checked to make sure it would function in my magazine. There were light marks on the bullet and I used a bullet comparator to obtain a just touching the lands seating depth.[/FONT][/COLOR][COLOR=black][/COLOR][/FONT] [COLOR=black][FONT=Calibri][FONT=Times New Roman][/FONT][/FONT][/COLOR] [COLOR=black][FONT=Calibri][FONT=Times New Roman]Next calculate the area of the bullet's cross section. For a .243 diameter bullet, that is (0.2432 ÷ 4) x 3.1416 = 0.0464 square inches. Multiply that area by the seating depth gives you the volume 0.0188 of the case occupied by the bullet, but it is in cubic inches. To convert cubic inches to grains of water, multiply by 252.8 grains of water per cubic inch which is 4.774 grains. Then subtract from case volume 52.0 – 4.774 = 47.23 grains. This a little off because the Berger bullet is a boat tail. I assume this is the maximum capacity before a compressed load is obtained. And from the literature at least 80% case capacity is necessary with powder so the minimum charge would be 47 x .8 or 38 grains. [/FONT][/FONT][/COLOR][COLOR=black][/COLOR] Robert [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Rifles, Reloading, Optics, Equipment
Reloading
Advice on bullet seating depth Berger 95 grain hybrid
Top