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
Rifles, Bullets, Barrels & Ballistics
Melonite barrel treatment
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="Bart B" data-source="post: 1125209" data-attributes="member: 5302"><p><strong>Re: What's Overbore???</strong></p><p></p><p>Ask several people what an overbore cartridge is and you'll probable get several different answers. All of which is why I did some barrel life comparisons people in competitive shooting disciplines got with different calibers and charge weights. Also included the barrel lives Sierra Bullets' test barrels delivered testing their stuff for accuracy.</p><p></p><p>One single thing stood out that was very consistent across all bore diameters. If the powder charge in grains had the same number as the bore's cross section in square millimeters, barrel life was about 3000 rounds. Example, a .308 Win has a bore diameter of 7.62 mm, its cross section area is about 45 square millimeters. Average charge weights for its various bullet weights are around 45 grains; more for light weight bullets, less for heavier ones. Barrel lives were about 3000 rounds for best accuracy; that's starting out at 1/4 MOA then opening up 50% to about 3/8 MOA.</p><p></p><p>If the powder charge was increased about 40% in larger 30 caliber cartridge cases, barrel lives were half as many or about 1500 rounds. Double the charge weight to 90 grains and barrel lives were one-fourth as many rounds; 750 in .300 Wby Mag's. Same thing with 22 caliber cartridges burning charge weights in the low 20's or 24 caliber ones' charge weights in the upper 20's.</p><p></p><p>Hunting rifle cartridges with the same standard getting not quite as good of accuracy starting out at about 3/4 to 1 MOA, they had twice the barrel life before accuracy degraded to about 1-1/3 to near 2 MOA or thereabouts after 6000 rounds. Military service rifle and ammo barrel lives were some three times as many rounds starting out at 2 or 3 MOA accuracy then ending at several MOA some 10,000 to 15,000 rounds later.</p></blockquote><p></p>
[QUOTE="Bart B, post: 1125209, member: 5302"] [b]Re: What's Overbore???[/b] Ask several people what an overbore cartridge is and you'll probable get several different answers. All of which is why I did some barrel life comparisons people in competitive shooting disciplines got with different calibers and charge weights. Also included the barrel lives Sierra Bullets' test barrels delivered testing their stuff for accuracy. One single thing stood out that was very consistent across all bore diameters. If the powder charge in grains had the same number as the bore's cross section in square millimeters, barrel life was about 3000 rounds. Example, a .308 Win has a bore diameter of 7.62 mm, its cross section area is about 45 square millimeters. Average charge weights for its various bullet weights are around 45 grains; more for light weight bullets, less for heavier ones. Barrel lives were about 3000 rounds for best accuracy; that's starting out at 1/4 MOA then opening up 50% to about 3/8 MOA. If the powder charge was increased about 40% in larger 30 caliber cartridge cases, barrel lives were half as many or about 1500 rounds. Double the charge weight to 90 grains and barrel lives were one-fourth as many rounds; 750 in .300 Wby Mag's. Same thing with 22 caliber cartridges burning charge weights in the low 20's or 24 caliber ones' charge weights in the upper 20's. Hunting rifle cartridges with the same standard getting not quite as good of accuracy starting out at about 3/4 to 1 MOA, they had twice the barrel life before accuracy degraded to about 1-1/3 to near 2 MOA or thereabouts after 6000 rounds. Military service rifle and ammo barrel lives were some three times as many rounds starting out at 2 or 3 MOA accuracy then ending at several MOA some 10,000 to 15,000 rounds later. [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Melonite barrel treatment
Top