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
Guesses on muzzle velocity, 300 RUM
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="Fitch" data-source="post: 337226" data-attributes="member: 19372"><p>The load you have calculates as over pressure in 70F and warmer conditions, or if you let a cartridge soak in a hot chamber. But it would be good to get chronotraph data to see if my predicted velocities are correct. If the predicted velocities are correct, the predicted pressure probably isn't far off either.</p><p> </p><p>The 3.7" COL is longer than I used and acts to reduce pressures significantly because it increases the initial chamber volume behind the bullet. The only data that would improve my prediction now is an accurate water grain capacity for your as-fired brass. The capacity I'm using now is 112.5g which is the QuickLoad default value for that cartridge. </p><p> </p><p>The updated results I get with that COL and a 26" barrel:</p><p> </p><p>90F 66,617 psi 3.101 fps</p><p>70F 64,294 psi 3,077 fps</p><p>50F 62,000 psi 3,051 fps</p><p> </p><p>I have no explanation for anybody else's data. I only go by what I measure myself. I will say that there are a lot of folks on the internet that are getting higher muzzle velocities and smaller groups than I am. </p><p> </p><p>Getting yourself a good chronograph, like a CED M2 will let you get your own data. If it were me, I'd definitly e-mail Berger as they suggest on this page</p><p> </p><p><a href="http://www.bergerbullets.com/Information/FAQ.html" target="_blank">http://www.bergerbullets.com/Information/FAQ.html</a> </p><p> </p><p>and ask them about load data for the bullet in your cartridge (besure and give them the COL you are using) and get starting and max loads from them. \</p><p> </p><p>The best powders, according to QuickLoad in descending order of maximum muzzle velocity (which says nothing about accuracy), are Vihtavouri N570, Hodgdon H870, Hodgdon Retumbo, Vihtavouri N560, Accurate MAGPRO, IMR7828 and IMR7828SSC.</p><p> </p><p>I hesitate to recommend it with out knowing your background but the QuickLoad software, which my estimates above are based on, used correctly (it comes with an excellent manual), can be a huge assett when it comes to understanding internal ballistics (that which happens between the time the primer fires and the bullet leaves the muzzle). It comes with two excellent external ballistics programs as well. Like any other simulation modeling tool it's output is only as good as the input. I treat it's output like I do the load maps in reloading manuals which means I never start at a QuickLoad predicted max load. I start 10% low and work up while documenting the chronotraph readings, looking at primers, checking for sticky extraction, etc. This SW is one of the better investments I made in reloading equipment. </p><p> </p><p>I have come up with a lot of good starting load and probable max load for a lot of cartridge bullet combinations using QuickLoad. I've selected cartridges, bullets, powders, barrel lengths and a number of other things based on combining QuickLoad studies, QuickTarget external ballistic results, data and equations in EXCEL from "Applied Ballistics for Long Range Shooting" by Bryan Litz. The result allows comparison of optimum game weights, point blank ranges on different game, for the various cartridges of interest. </p><p> </p><p>However, if you aren't an analytical type (I'm a retired engineer) you may not find that approach to be your best approach to learning. </p><p> </p><p>A few rainy/snowy days at the computer with some good coffee, pencil paper, and calculator, doing what-if studies on powders and experimenting with the effect of seating depth and bullet selection has given me the opportunity to learn and gain mor indepth understanding. I'm definitely not an expert, but I'm finally at the point of appreciating how much I don't know.</p><p> </p><p>Fitch</p></blockquote><p></p>
[QUOTE="Fitch, post: 337226, member: 19372"] The load you have calculates as over pressure in 70F and warmer conditions, or if you let a cartridge soak in a hot chamber. But it would be good to get chronotraph data to see if my predicted velocities are correct. If the predicted velocities are correct, the predicted pressure probably isn't far off either. The 3.7" COL is longer than I used and acts to reduce pressures significantly because it increases the initial chamber volume behind the bullet. The only data that would improve my prediction now is an accurate water grain capacity for your as-fired brass. The capacity I'm using now is 112.5g which is the QuickLoad default value for that cartridge. The updated results I get with that COL and a 26" barrel: 90F 66,617 psi 3.101 fps 70F 64,294 psi 3,077 fps 50F 62,000 psi 3,051 fps I have no explanation for anybody else's data. I only go by what I measure myself. I will say that there are a lot of folks on the internet that are getting higher muzzle velocities and smaller groups than I am. Getting yourself a good chronograph, like a CED M2 will let you get your own data. If it were me, I'd definitly e-mail Berger as they suggest on this page [URL]http://www.bergerbullets.com/Information/FAQ.html[/URL] and ask them about load data for the bullet in your cartridge (besure and give them the COL you are using) and get starting and max loads from them. \ The best powders, according to QuickLoad in descending order of maximum muzzle velocity (which says nothing about accuracy), are Vihtavouri N570, Hodgdon H870, Hodgdon Retumbo, Vihtavouri N560, Accurate MAGPRO, IMR7828 and IMR7828SSC. I hesitate to recommend it with out knowing your background but the QuickLoad software, which my estimates above are based on, used correctly (it comes with an excellent manual), can be a huge assett when it comes to understanding internal ballistics (that which happens between the time the primer fires and the bullet leaves the muzzle). It comes with two excellent external ballistics programs as well. Like any other simulation modeling tool it's output is only as good as the input. I treat it's output like I do the load maps in reloading manuals which means I never start at a QuickLoad predicted max load. I start 10% low and work up while documenting the chronotraph readings, looking at primers, checking for sticky extraction, etc. This SW is one of the better investments I made in reloading equipment. I have come up with a lot of good starting load and probable max load for a lot of cartridge bullet combinations using QuickLoad. I've selected cartridges, bullets, powders, barrel lengths and a number of other things based on combining QuickLoad studies, QuickTarget external ballistic results, data and equations in EXCEL from "Applied Ballistics for Long Range Shooting" by Bryan Litz. The result allows comparison of optimum game weights, point blank ranges on different game, for the various cartridges of interest. However, if you aren't an analytical type (I'm a retired engineer) you may not find that approach to be your best approach to learning. A few rainy/snowy days at the computer with some good coffee, pencil paper, and calculator, doing what-if studies on powders and experimenting with the effect of seating depth and bullet selection has given me the opportunity to learn and gain mor indepth understanding. I'm definitely not an expert, but I'm finally at the point of appreciating how much I don't know. Fitch [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Rifles, Reloading, Optics, Equipment
Reloading
Guesses on muzzle velocity, 300 RUM
Top