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Rifles, Reloading, Optics, Equipment
Gunsmithing
6 br budget build
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<blockquote data-quote="FearNoWind" data-source="post: 1052617" data-attributes="member: 50867"><p>"Free bore" (aka throat or lead) is that portion of the chamber immediately ahead of the lands.</p><p>This diagram may help you better understand it:</p><p></p><p><a href="https://www.google.com/search?q=rifle+chamber+free+bore&client=ubuntu&hs=jA7&channel=fs&tbm=isch&imgil=XBuF6t7Jwx3FJM%253A%253Bp6qcYwC9OYcD8M%253Bhttp%25253A%25252F%25252Fbisonballistics.com%25252Farticles%25252Fan-introduction-to-rifle-chambers&source=iu&pf=m&fir=XBuF6t7Jwx3FJM%253A%252Cp6qcYwC9OYcD8M%252C_&usg=__4gs065EvKw4moqH4GH1t_NlqcCw%3D&biw=1231&bih=927&ved=0CEEQyjc&ei=nGXjVMXuBtTnoATM7IK4Ag#imgdii=_&imgrc=aoSsn5HClt_ABM%253A%3BA7wd4PzOXui9eM%3Bhttp%253A%252F%252Fbenchrest.com%252Fattachment.php%253Fattachmentid%253D9251%2526d%253D1267208204%3Bhttp%253A%252F%252Fbenchrest.com%252Fshowthread.php%253F67906-What-does-quot-zero-quot-freebore-mean%3B370%3B242" target="_blank">https://www.google.com/search?q=rifle+chamber+free+bore&client=ubuntu&hs=jA7&channel=fs&tbm=isch&imgil=XBuF6t7Jwx3FJM%253A%253Bp6qcYwC9OYcD8M%253Bhttp%25253A%25252F%25252Fbisonballistics.com%25252Farticles%25252Fan-introduction-to-rifle-chambers&source=iu&pf=m&fir=XBuF6t7Jwx3FJM%253A%252Cp6qcYwC9OYcD8M%252C_&usg=__4gs065EvKw4moqH4GH1t_NlqcCw%3D&biw=1231&bih=927&ved=0CEEQyjc&ei=nGXjVMXuBtTnoATM7IK4Ag#imgdii=_&imgrc=aoSsn5HClt_ABM%253A%3BA7wd4PzOXui9eM%3Bhttp%253A%252F%252Fbenchrest.com%252Fattachment.php%253Fattachmentid%253D9251%2526d%253D1267208204%3Bhttp%253A%252F%252Fbenchrest.com%252Fshowthread.php%253F67906-What-does-quot-zero-quot-freebore-mean%3B370%3B242</a></p><p></p><p>This diagram is a bit more complex but if you understand engineering drawings it too may help you:</p><p></p><p><a href="https://www.google.com/search?q=rifle+chamber+free+bore&client=ubuntu&hs=jA7&channel=fs&tbm=isch&imgil=XBuF6t7Jwx3FJM%253A%253Bp6qcYwC9OYcD8M%253Bhttp%25253A%25252F%25252Fbisonballistics.com%25252Farticles%25252Fan-introduction-to-rifle-chambers&source=iu&pf=m&fir=XBuF6t7Jwx3FJM%253A%252Cp6qcYwC9OYcD8M%252C_&usg=__4gs065EvKw4moqH4GH1t_NlqcCw%3D&biw=1231&bih=927&ved=0CEEQyjc&ei=nGXjVMXuBtTnoATM7IK4Ag#imgdii=aoSsn5HClt_ABM%3A%3Byt3Qw6xpss4FuM%3BaoSsn5HClt_ABM%3A&imgrc=aoSsn5HClt_ABM%253A%3BA7wd4PzOXui9eM%3Bhttp%253A%252F%252Fbenchrest.com%252Fattachment.php%253Fattachmentid%253D9251%2526d%253D1267208204%3Bhttp%253A%252F%252Fbenchrest.com%252Fshowthread.php%253F67906-What-does-quot-zero-quot-freebore-mean%3B370%3B242" target="_blank">https://www.google.com/search?q=rifle+chamber+free+bore&client=ubuntu&hs=jA7&channel=fs&tbm=isch&imgil=XBuF6t7Jwx3FJM%3A%3Bp6qcYwC9OYcD8M%3Bhttp%253A%252F%252Fbisonballistics.com%252Farticles%252Fan-introduction-to-rifle-chambers&source=iu&pf=m&fir=XBuF6t7Jwx3FJM%3A%2Cp6qcYwC9OYcD8M%2C_&usg=__4gs065EvKw4moqH4GH1t_NlqcCw=&biw=1231&bih=927&ved=0CEEQyjc&ei=nGXjVMXuBtTnoATM7IK4Ag#imgdii=aoSsn5HClt_ABM:;yt3Qw6xpss4FuM;aoSsn5HClt_ABM:&imgrc=aoSsn5HClt_ABM%3A;A7wd4PzOXui9eM;http%3A%2F%2Fbenchrest.com%2Fattachment.php%3Fattachmentid%3D9251%26d%3D1267208204;http%3A%2F%2Fbenchrest.com%2Fshowthread.php%3F67906-What-does-quot-zero-quot-freebore-mean;370;242</a></p><p></p><p>If you study the diagrams you'll note that the overall length possibilities for the bullet is limted to the distance from the base of the case to where the bullet's ogive contacts the lands. Once the ogive contacts the lands the bullet's OAL can't be increased. If you increase the freebore the bullet can be moved further out within the case neck. That increases case volume, decreases surface contact between the bullet and the case neck, and increases the seating depth possibilities.</p><p>Whether there's any advantage one way or the other depends, IMO, on how you want to use the rifle. But there's more to it than just free bore lengths. Lead angle (the mechanical feature that guides the bullet into the lands) is another factor to consider:</p><p></p><p><a href="https://www.google.com/search?q=rifle+chamber+lead+angle&client=ubuntu&hs=oQ7&channel=fs&tbm=isch&imgil=WKjym5fxg0C_gM%253A%253BXMAAARI-44OsfM%253Bhttp%25253A%25252F%25252Fcastboolits.gunloads.com%25252Farchive%25252Findex.php%25252Ft-128691.html&source=iu&pf=m&fir=WKjym5fxg0C_gM%253A%252CXMAAARI-44OsfM%252C_&usg=__jsO9fbLgnQF9Y57CahscM40a2zc%3D&biw=1231&bih=927&ved=0CCkQyjc&ei=gWnjVKmOLZXhoATqjIDwDw#imgdii=_&imgrc=WKjym5fxg0C_gM%253A%3BXMAAARI-44OsfM%3Bhttp%253A%252F%252Fi47.photobucket.com%252Falbums%252Ff165%252FRealTexasMac%252FFigure4540-6545-90ThroatBore.jpg%3Bhttp%253A%252F%252Fcastboolits.gunloads.com%252Farchive%252Findex.php%252Ft-128691.html%3B1350%3B617" target="_blank">https://www.google.com/search?q=rifle+chamber+lead+angle&client=ubuntu&hs=oQ7&channel=fs&tbm=isch&imgil=WKjym5fxg0C_gM%3A%3BXMAAARI-44OsfM%3Bhttp%253A%252F%252Fcastboolits.gunloads.com%252Farchive%252Findex.php%252Ft-128691.html&source=iu&pf=m&fir=WKjym5fxg0C_gM%3A%2CXMAAARI-44OsfM%2C_&usg=__jsO9fbLgnQF9Y57CahscM40a2zc=&biw=1231&bih=927&ved=0CCkQyjc&ei=gWnjVKmOLZXhoATqjIDwDw#imgdii=_&imgrc=WKjym5fxg0C_gM%3A;XMAAARI-44OsfM;http%3A%2F%2Fi47.photobucket.com%2Falbums%2Ff165%2FRealTexasMac%2FFigure4540-6545-90ThroatBore.jpg;http%3A%2F%2Fcastboolits.gunloads.com%2Farchive%2Findex.php%2Ft-128691.html;1350;617</a></p><p></p><p>Are you building a hunting rifle or a competition target rifle?</p></blockquote><p></p>
[QUOTE="FearNoWind, post: 1052617, member: 50867"] "Free bore" (aka throat or lead) is that portion of the chamber immediately ahead of the lands. This diagram may help you better understand it: [URL="https://www.google.com/search?q=rifle+chamber+free+bore&client=ubuntu&hs=jA7&channel=fs&tbm=isch&imgil=XBuF6t7Jwx3FJM%253A%253Bp6qcYwC9OYcD8M%253Bhttp%25253A%25252F%25252Fbisonballistics.com%25252Farticles%25252Fan-introduction-to-rifle-chambers&source=iu&pf=m&fir=XBuF6t7Jwx3FJM%253A%252Cp6qcYwC9OYcD8M%252C_&usg=__4gs065EvKw4moqH4GH1t_NlqcCw%3D&biw=1231&bih=927&ved=0CEEQyjc&ei=nGXjVMXuBtTnoATM7IK4Ag#imgdii=_&imgrc=aoSsn5HClt_ABM%253A%3BA7wd4PzOXui9eM%3Bhttp%253A%252F%252Fbenchrest.com%252Fattachment.php%253Fattachmentid%253D9251%2526d%253D1267208204%3Bhttp%253A%252F%252Fbenchrest.com%252Fshowthread.php%253F67906-What-does-quot-zero-quot-freebore-mean%3B370%3B242"]https://www.google.com/search?q=rifle+chamber+free+bore&client=ubuntu&hs=jA7&channel=fs&tbm=isch&imgil=XBuF6t7Jwx3FJM%253A%253Bp6qcYwC9OYcD8M%253Bhttp%25253A%25252F%25252Fbisonballistics.com%25252Farticles%25252Fan-introduction-to-rifle-chambers&source=iu&pf=m&fir=XBuF6t7Jwx3FJM%253A%252Cp6qcYwC9OYcD8M%252C_&usg=__4gs065EvKw4moqH4GH1t_NlqcCw%3D&biw=1231&bih=927&ved=0CEEQyjc&ei=nGXjVMXuBtTnoATM7IK4Ag#imgdii=_&imgrc=aoSsn5HClt_ABM%253A%3BA7wd4PzOXui9eM%3Bhttp%253A%252F%252Fbenchrest.com%252Fattachment.php%253Fattachmentid%253D9251%2526d%253D1267208204%3Bhttp%253A%252F%252Fbenchrest.com%252Fshowthread.php%253F67906-What-does-quot-zero-quot-freebore-mean%3B370%3B242[/URL] This diagram is a bit more complex but if you understand engineering drawings it too may help you: [URL]https://www.google.com/search?q=rifle+chamber+free+bore&client=ubuntu&hs=jA7&channel=fs&tbm=isch&imgil=XBuF6t7Jwx3FJM%253A%253Bp6qcYwC9OYcD8M%253Bhttp%25253A%25252F%25252Fbisonballistics.com%25252Farticles%25252Fan-introduction-to-rifle-chambers&source=iu&pf=m&fir=XBuF6t7Jwx3FJM%253A%252Cp6qcYwC9OYcD8M%252C_&usg=__4gs065EvKw4moqH4GH1t_NlqcCw%3D&biw=1231&bih=927&ved=0CEEQyjc&ei=nGXjVMXuBtTnoATM7IK4Ag#imgdii=aoSsn5HClt_ABM%3A%3Byt3Qw6xpss4FuM%3BaoSsn5HClt_ABM%3A&imgrc=aoSsn5HClt_ABM%253A%3BA7wd4PzOXui9eM%3Bhttp%253A%252F%252Fbenchrest.com%252Fattachment.php%253Fattachmentid%253D9251%2526d%253D1267208204%3Bhttp%253A%252F%252Fbenchrest.com%252Fshowthread.php%253F67906-What-does-quot-zero-quot-freebore-mean%3B370%3B242[/URL] If you study the diagrams you'll note that the overall length possibilities for the bullet is limted to the distance from the base of the case to where the bullet's ogive contacts the lands. Once the ogive contacts the lands the bullet's OAL can't be increased. If you increase the freebore the bullet can be moved further out within the case neck. That increases case volume, decreases surface contact between the bullet and the case neck, and increases the seating depth possibilities. Whether there's any advantage one way or the other depends, IMO, on how you want to use the rifle. But there's more to it than just free bore lengths. Lead angle (the mechanical feature that guides the bullet into the lands) is another factor to consider: [URL]https://www.google.com/search?q=rifle+chamber+lead+angle&client=ubuntu&hs=oQ7&channel=fs&tbm=isch&imgil=WKjym5fxg0C_gM%253A%253BXMAAARI-44OsfM%253Bhttp%25253A%25252F%25252Fcastboolits.gunloads.com%25252Farchive%25252Findex.php%25252Ft-128691.html&source=iu&pf=m&fir=WKjym5fxg0C_gM%253A%252CXMAAARI-44OsfM%252C_&usg=__jsO9fbLgnQF9Y57CahscM40a2zc%3D&biw=1231&bih=927&ved=0CCkQyjc&ei=gWnjVKmOLZXhoATqjIDwDw#imgdii=_&imgrc=WKjym5fxg0C_gM%253A%3BXMAAARI-44OsfM%3Bhttp%253A%252F%252Fi47.photobucket.com%252Falbums%252Ff165%252FRealTexasMac%252FFigure4540-6545-90ThroatBore.jpg%3Bhttp%253A%252F%252Fcastboolits.gunloads.com%252Farchive%252Findex.php%252Ft-128691.html%3B1350%3B617[/URL] Are you building a hunting rifle or a competition target rifle? [/QUOTE]
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