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
Over bore?
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="lynn" data-source="post: 36390" data-attributes="member: 1479"><p>If you figure out the amount of powder to reach different velocity levels it will help show why some cartridges are considered more efficient.If we stick to a 107 Sierra bullet in all of the examples it will help.6BR at 2950 fps uses 31 gr of powder.A 243 will take 43.5 gr to get the same velocity.A 244 will take 44.5 gr to get the same velocity.If you Ackley improve the 244 case it takes 1 less grain or 43.5 of powder to get the same velocity as the standard case.If we go to 6/284 it takes 43 gr to get the same velocity while a 6mm-06 will take 46.8 grains as does a 240 Weatherby.In this example with the velocity limited the little 6BR is getting 95 feet per second per grain of powder burned.The 6mm-06 is getting 63 feet per second per gr of powder burned and is therefore less efficient.The same thing can be done with the 6.5X284 and the 6.5 WSSM to show which one is more efficient but as i don't own either can't give you the actual numbers.If you compare some of the big 30 caliber rounds with lighter bullets the term overbore is easier to see.A 300 Weatherby needs 78 gr of powder to push a 165 gr bullet 3300 fps.The 300 Ultra mag needs approximately 15 gr more powder depending on type to do the same thing and the 30-378 needs up to 118 gr to get the same velocity.That is 40 grains more powder or a whole 308 winchester load added on to get the same velocity.I would consider the 30-378 overbore for shooting 165 grain bullets and not very efficient with that weight bullet.</p><p>Lynn</p></blockquote><p></p>
[QUOTE="lynn, post: 36390, member: 1479"] If you figure out the amount of powder to reach different velocity levels it will help show why some cartridges are considered more efficient.If we stick to a 107 Sierra bullet in all of the examples it will help.6BR at 2950 fps uses 31 gr of powder.A 243 will take 43.5 gr to get the same velocity.A 244 will take 44.5 gr to get the same velocity.If you Ackley improve the 244 case it takes 1 less grain or 43.5 of powder to get the same velocity as the standard case.If we go to 6/284 it takes 43 gr to get the same velocity while a 6mm-06 will take 46.8 grains as does a 240 Weatherby.In this example with the velocity limited the little 6BR is getting 95 feet per second per grain of powder burned.The 6mm-06 is getting 63 feet per second per gr of powder burned and is therefore less efficient.The same thing can be done with the 6.5X284 and the 6.5 WSSM to show which one is more efficient but as i don't own either can't give you the actual numbers.If you compare some of the big 30 caliber rounds with lighter bullets the term overbore is easier to see.A 300 Weatherby needs 78 gr of powder to push a 165 gr bullet 3300 fps.The 300 Ultra mag needs approximately 15 gr more powder depending on type to do the same thing and the 30-378 needs up to 118 gr to get the same velocity.That is 40 grains more powder or a whole 308 winchester load added on to get the same velocity.I would consider the 30-378 overbore for shooting 165 grain bullets and not very efficient with that weight bullet. Lynn [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Over bore?
Top