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: 337119" data-attributes="member: 19372"><p>I modeled that load in QuickLoad as well as I can with out knowing the COL at which you are seating the bullet. The COL has a noticable effect on both pressure and velocity. The model is not a replacement for a chronograph but it is a good place to go for an estimate if one doesn't have a chronograph. I use IMR7828 in my .243 with 95g Nosler BT bullets and the QuickLoad models are for that cartridge are within 2% on MV. </p><p> </p><p>Results of modeling your load:</p><p> </p><p>First, at least in QuickLoad, that looks like a pretty hot load. At 50F the calculated peak pressure is within 600 psi of max at 64,400 psi in a rifle that has a 65,000 psi maximum. The muzzle velocity is predicted to be 3,082 ft/sec. </p><p> </p><p>At 70F the predicted pressure goes up to 66,790 psi and the MV goes to 3107 fps. </p><p> </p><p>At 90F (not an uncommon summer temperature) the pressure goes up to 69,215 psi with a muzzle velocity of 3,131 fps.</p><p> </p><p>I have two recommendations: First, definitely shoot that load through a chronograph and compare your measured MV with the predicted values in the manual for the bullets. If you are higher than the velocity predictions in the manual for your powder charge using the same length barrel, you might consider backing off on the powder charge. </p><p> </p><p>Second, make darn sure your bullet is not touching or seated into the lands. That will increase the peak pressure another 6,000 to 7,000 psi.</p><p> </p><p>Fitch</p></blockquote><p></p>
[QUOTE="Fitch, post: 337119, member: 19372"] I modeled that load in QuickLoad as well as I can with out knowing the COL at which you are seating the bullet. The COL has a noticable effect on both pressure and velocity. The model is not a replacement for a chronograph but it is a good place to go for an estimate if one doesn't have a chronograph. I use IMR7828 in my .243 with 95g Nosler BT bullets and the QuickLoad models are for that cartridge are within 2% on MV. Results of modeling your load: First, at least in QuickLoad, that looks like a pretty hot load. At 50F the calculated peak pressure is within 600 psi of max at 64,400 psi in a rifle that has a 65,000 psi maximum. The muzzle velocity is predicted to be 3,082 ft/sec. At 70F the predicted pressure goes up to 66,790 psi and the MV goes to 3107 fps. At 90F (not an uncommon summer temperature) the pressure goes up to 69,215 psi with a muzzle velocity of 3,131 fps. I have two recommendations: First, definitely shoot that load through a chronograph and compare your measured MV with the predicted values in the manual for the bullets. If you are higher than the velocity predictions in the manual for your powder charge using the same length barrel, you might consider backing off on the powder charge. Second, make darn sure your bullet is not touching or seated into the lands. That will increase the peak pressure another 6,000 to 7,000 psi. Fitch [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Rifles, Reloading, Optics, Equipment
Reloading
Guesses on muzzle velocity, 300 RUM
Top