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
Hunting
Long Range Hunting & Shooting
Freebore Discussion
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="VinceMule" data-source="post: 2697268" data-attributes="member: 122164"><p>Ok, on a new barrel, let's say you have a Cartridge base to Ogive at 2.000. As the barrel is fired hundreds of rounds, let's say now your CBTO has grown .070 at .2070. While you can not measure it, the throat dia has also grown for some distance down the bore. The use of a Grizzley rod with a set of reamer pilots that vary .0002 in dia is an easy tool to measure throat/barrel dia with. The dia will grow over the life of the barrel for 10-14 inches depending on the cartridge and the heat index of the powder used.</p><p></p><p>As the barrel wears, the bore does not seal the bullet in the barrel as tightly/quickly as it did when the barrel was new, there is a loss of pressure and velocity. Sometimes, You can add more powder in some cases to bring up the pressure to where it was when the bbl was new, and maintain that velocity where the barrel liked the harmonics...this is critical in your thinking. Bores vary in diameter, and I wish gunsmiths would stamp on the outside of the barrel which dia reamer pilot they found "fit" the barrel when they were chambering.</p><p></p><p>If you found the barrel to be the most accurate with a bullet jump of .010 when new, accuracy can be maintained by seating the bullet out maintaining that .010 jump, for as long as you can with the barrel being serviceable with Mag length. Some bullets may like a .120 jump when new, you never know. Often, you may be forced into using the rifle as a single shot to get that 2" accuracy at 600 yards. </p><p></p><p>It is amazing at how many Remington 700's in 7 Mag, 7/08, and 280 Rem shoot very tiny 3-shot groups, less than 3/8", with the bullet just barely kissing the lands. Bullets have to be sorted by ogive length, and Nosler 120,140, and 150g Ballistic tips shoot extremely tiny groups, so do the 175g Nosler long-range accubonds .003 off the lands.</p><p></p><p>I have Wyatt's extended mag boxes installed in all of my Remingtons which gives me another .125 in length, and they do offer a 4.000-length mag box. The action has to be milled out on the bottom and the bolt stop cut back to accommodate the extra bolt travel to pick up the back of the cartridge case.</p><p></p><p><strong><span style="color: rgb(184, 49, 47)">The Heat Index of the powder you shoot is a major factor in how the bore Wears in dia. and land height taper</span></strong>. We are used to seeing pics from a Teslong on bore pitting, seeing a picture of bore dia wear, graduated in .0002 is a game changer. With Teslong, create a movie or pics of a barrel, save that barrel's pics on a single memory stick, and watch the erosion over the number of documented shots...barrel history.</p><p></p><p>With some cartridges, the Base to ogive is so long that they can not touch the lands on a brand-new barrel while using the magazine... and this is one heck of a mess to deal with using VLD type of bullets...sometimes you get lucky.</p><p></p><p>I have my own 300 yd rifle range, and shoot out of a heated AC house, reloading on the spot.</p></blockquote><p></p>
[QUOTE="VinceMule, post: 2697268, member: 122164"] Ok, on a new barrel, let's say you have a Cartridge base to Ogive at 2.000. As the barrel is fired hundreds of rounds, let's say now your CBTO has grown .070 at .2070. While you can not measure it, the throat dia has also grown for some distance down the bore. The use of a Grizzley rod with a set of reamer pilots that vary .0002 in dia is an easy tool to measure throat/barrel dia with. The dia will grow over the life of the barrel for 10-14 inches depending on the cartridge and the heat index of the powder used. As the barrel wears, the bore does not seal the bullet in the barrel as tightly/quickly as it did when the barrel was new, there is a loss of pressure and velocity. Sometimes, You can add more powder in some cases to bring up the pressure to where it was when the bbl was new, and maintain that velocity where the barrel liked the harmonics...this is critical in your thinking. Bores vary in diameter, and I wish gunsmiths would stamp on the outside of the barrel which dia reamer pilot they found "fit" the barrel when they were chambering. If you found the barrel to be the most accurate with a bullet jump of .010 when new, accuracy can be maintained by seating the bullet out maintaining that .010 jump, for as long as you can with the barrel being serviceable with Mag length. Some bullets may like a .120 jump when new, you never know. Often, you may be forced into using the rifle as a single shot to get that 2" accuracy at 600 yards. It is amazing at how many Remington 700's in 7 Mag, 7/08, and 280 Rem shoot very tiny 3-shot groups, less than 3/8", with the bullet just barely kissing the lands. Bullets have to be sorted by ogive length, and Nosler 120,140, and 150g Ballistic tips shoot extremely tiny groups, so do the 175g Nosler long-range accubonds .003 off the lands. I have Wyatt's extended mag boxes installed in all of my Remingtons which gives me another .125 in length, and they do offer a 4.000-length mag box. The action has to be milled out on the bottom and the bolt stop cut back to accommodate the extra bolt travel to pick up the back of the cartridge case. [B][COLOR=rgb(184, 49, 47)]The Heat Index of the powder you shoot is a major factor in how the bore Wears in dia. and land height taper[/COLOR][/B]. We are used to seeing pics from a Teslong on bore pitting, seeing a picture of bore dia wear, graduated in .0002 is a game changer. With Teslong, create a movie or pics of a barrel, save that barrel's pics on a single memory stick, and watch the erosion over the number of documented shots...barrel history. With some cartridges, the Base to ogive is so long that they can not touch the lands on a brand-new barrel while using the magazine... and this is one heck of a mess to deal with using VLD type of bullets...sometimes you get lucky. I have my own 300 yd rifle range, and shoot out of a heated AC house, reloading on the spot. [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Hunting
Long Range Hunting & Shooting
Freebore Discussion
Top