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
Losing velocity...it's not the chrono..any ideas
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="Pdvdh" data-source="post: 1173368" data-attributes="member: 4191"><p>1) Resize all cases using the same technique/dies, prior to seating any bullets;</p><p>2) Lube the insides of all of the case necks with Imperial Sizing Wax on a Q-Tip, and then remove the excess with a dry Q-Tip prior to powder charging and seating the bullets. I recently pulled close to 1000 bullets from some .223 Remington handloaded cartridges. Some of the case necks were lubed with Imperial wax and some weren't. The variance in the force required to pull the bullets from the waxed case necks was MUCH less than the variance in pulling the bullets from the un-waxed case necks. Increased case neck tension (or anything else that increases the force required to cause initial bullet movement in the chamber/bore) will increase pressure and muzzle velocity, all other factors held constant. During this process I also experienced a HUGE sensed difference in case neck tension between cases with case necks/shoulders that had been annealed prior to seating the bullets, and case necks/shoulders that had not been annealed prior to seating the bullets. Lapua brass is annealed from the factory, so this isn't likely to be the source of your high ES / SD. Unless you've fired and resized the original use cases a number of times, and then load and compare MV to new virgin brass casings. Higher case neck tension = higher MV. Based on the description you've provided, I believe that following these first two "standard practices" will eliminate the majority of your ES / SD in muzzle velocity;</p><p>3) Make sure all bullets are seated to the same depth in the cartridge cases. Especially make certain that bullets aren't seated to variable depths such that some are touching the lands of the rifling when chambered, and some bullets are seated deeper and are not touching the lands of the rifling. The difference between these two seating depths can cause a big difference in MV. I like to keep bullets a minimum of ~0.010" off the rifling if I'm not jamming bullets into the rifling, or a minimum of ~0.010" into the rifling if I'm jamming them. I don't like to take the risk that some bullets are touching the lands, and some aren't, or are only barely jammed;</p><p>4) Make sure you've used the same primers in all of your loads. This sounds simple enough, but if you have a variety of primers in your reloading room, stuff like this has been known to happen. Don't ask how I know why <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /> Magnum primers or another brand of primers with a greater/hotter "spark" will increase MV;</p><p>5) Use the same powder, from the same Lot of powder, whenever possible. When changing Lots of powder, don't be surprised if you realize some change in muzzle velocity;</p><p>6) Weigh your cases to ensure they're approximately the same weight. This shouldn't be much of the problem if you're using Lapua brass and they're all from the same box. But it doesn't take long to do this, and it's helped me identify the source of variable MV in the past. In one extreme instance, I once measured a casing that weighed notably more than the others. After scratching some hair off my head, I finally looked inside the case and found a curly cued string of brass inside the casing, which accounted for the extra weight. Looked like a shoe string French fry - the curly type. Casing weight is an indication of the internal case volume. Higher case weight will typically have lesser internal volume, causing higher pressure and higher velocity, compared to the identical load in a lighter weight casing with greater internal volume;</p><p>7) Make sure your bore is fouled before recording MV for your records. A clean bore will almost always result in a differing MV compared to the same load in the same rifle after the bore is fouled with <u>at least</u> one shot. Sometimes it takes two rounds fired down the bore for MV to stabilize, <em>but a first fouling shot eliminates the majority of the difference</em>; [PS: This obviously means your bore should be fouled before you begin your hunt - if you're relying on fouled bore MV in your ballistics program.]</p><p>8) Make sure that when you're chronographing MV, that the temperature of your ammunition AND rifle bore is about the same, in order to rule out temperature caused variations in MV. Higher the temperature the higher the MV. If you're comparing muzzle velocity on a day when the ambient temperature is 20F higher or lower, you could expect some difference in MV - all other factors held constant. Also, as the bore heats up with additional repetitive shots fired, I have often seen MV increase/decrease compared to the first shot or two fired down the ambient temperature bore. When I record MV versus temperature for entry of MV info. into my ballistic program, I try to ensure the the bore and ammo return to ambient temperature prior to firing the next shot over the chronographs;</p><p>9) Make certain all skyscreens for your chronograph are in the same intensity of ambient light. Biggest example is do not have one skyscreen in the shade while the other two are exposed to direct sunlight.</p><p></p><p>These are the MV affecting factors that come to mind. There may be others that I've not experienced, or that I've not remembered to include at this moment in time. However based on the information you provided in your original post, these steps are the ones that came to mind.</p><p></p><p>Again, I think if you incorporate the first two items above into your reloading regime, that you'll find that the majority of your difference in MV will be resolved - <u>based on the information you've provided</u>. The Imperial Sizing Die Wax will help minimize the differences in the forces holding the bullet in the case neck no matter all the other items that could cause variable case neck-caused bullet release force in your reloaded ammunition. I didn't include this as a mandatory step in my reloading regiment until the experiences and knowledge gleaned form pulling 1000 bullets from differing brands of cartridge cases, with case necks prepped somewhat differently among the various reloaded cartridges.</p><p></p><p>Hope this is useful, and let us know what you eventually determine to be the source of your high difference in MVs between your prior reloads, and the "new" ones in the virgin Lapua cases. It's good to learn from others' experiences.</p></blockquote><p></p>
[QUOTE="Pdvdh, post: 1173368, member: 4191"] 1) Resize all cases using the same technique/dies, prior to seating any bullets; 2) Lube the insides of all of the case necks with Imperial Sizing Wax on a Q-Tip, and then remove the excess with a dry Q-Tip prior to powder charging and seating the bullets. I recently pulled close to 1000 bullets from some .223 Remington handloaded cartridges. Some of the case necks were lubed with Imperial wax and some weren't. The variance in the force required to pull the bullets from the waxed case necks was MUCH less than the variance in pulling the bullets from the un-waxed case necks. Increased case neck tension (or anything else that increases the force required to cause initial bullet movement in the chamber/bore) will increase pressure and muzzle velocity, all other factors held constant. During this process I also experienced a HUGE sensed difference in case neck tension between cases with case necks/shoulders that had been annealed prior to seating the bullets, and case necks/shoulders that had not been annealed prior to seating the bullets. Lapua brass is annealed from the factory, so this isn't likely to be the source of your high ES / SD. Unless you've fired and resized the original use cases a number of times, and then load and compare MV to new virgin brass casings. Higher case neck tension = higher MV. Based on the description you've provided, I believe that following these first two "standard practices" will eliminate the majority of your ES / SD in muzzle velocity; 3) Make sure all bullets are seated to the same depth in the cartridge cases. Especially make certain that bullets aren't seated to variable depths such that some are touching the lands of the rifling when chambered, and some bullets are seated deeper and are not touching the lands of the rifling. The difference between these two seating depths can cause a big difference in MV. I like to keep bullets a minimum of ~0.010" off the rifling if I'm not jamming bullets into the rifling, or a minimum of ~0.010" into the rifling if I'm jamming them. I don't like to take the risk that some bullets are touching the lands, and some aren't, or are only barely jammed; 4) Make sure you've used the same primers in all of your loads. This sounds simple enough, but if you have a variety of primers in your reloading room, stuff like this has been known to happen. Don't ask how I know why :) Magnum primers or another brand of primers with a greater/hotter "spark" will increase MV; 5) Use the same powder, from the same Lot of powder, whenever possible. When changing Lots of powder, don't be surprised if you realize some change in muzzle velocity; 6) Weigh your cases to ensure they're approximately the same weight. This shouldn't be much of the problem if you're using Lapua brass and they're all from the same box. But it doesn't take long to do this, and it's helped me identify the source of variable MV in the past. In one extreme instance, I once measured a casing that weighed notably more than the others. After scratching some hair off my head, I finally looked inside the case and found a curly cued string of brass inside the casing, which accounted for the extra weight. Looked like a shoe string French fry - the curly type. Casing weight is an indication of the internal case volume. Higher case weight will typically have lesser internal volume, causing higher pressure and higher velocity, compared to the identical load in a lighter weight casing with greater internal volume; 7) Make sure your bore is fouled before recording MV for your records. A clean bore will almost always result in a differing MV compared to the same load in the same rifle after the bore is fouled with [U]at least[/U] one shot. Sometimes it takes two rounds fired down the bore for MV to stabilize, [I]but a first fouling shot eliminates the majority of the difference[/I]; [PS: This obviously means your bore should be fouled before you begin your hunt - if you're relying on fouled bore MV in your ballistics program.] 8) Make sure that when you're chronographing MV, that the temperature of your ammunition AND rifle bore is about the same, in order to rule out temperature caused variations in MV. Higher the temperature the higher the MV. If you're comparing muzzle velocity on a day when the ambient temperature is 20F higher or lower, you could expect some difference in MV - all other factors held constant. Also, as the bore heats up with additional repetitive shots fired, I have often seen MV increase/decrease compared to the first shot or two fired down the ambient temperature bore. When I record MV versus temperature for entry of MV info. into my ballistic program, I try to ensure the the bore and ammo return to ambient temperature prior to firing the next shot over the chronographs; 9) Make certain all skyscreens for your chronograph are in the same intensity of ambient light. Biggest example is do not have one skyscreen in the shade while the other two are exposed to direct sunlight. These are the MV affecting factors that come to mind. There may be others that I've not experienced, or that I've not remembered to include at this moment in time. However based on the information you provided in your original post, these steps are the ones that came to mind. Again, I think if you incorporate the first two items above into your reloading regime, that you'll find that the majority of your difference in MV will be resolved - [U]based on the information you've provided[/U]. The Imperial Sizing Die Wax will help minimize the differences in the forces holding the bullet in the case neck no matter all the other items that could cause variable case neck-caused bullet release force in your reloaded ammunition. I didn't include this as a mandatory step in my reloading regiment until the experiences and knowledge gleaned form pulling 1000 bullets from differing brands of cartridge cases, with case necks prepped somewhat differently among the various reloaded cartridges. Hope this is useful, and let us know what you eventually determine to be the source of your high difference in MVs between your prior reloads, and the "new" ones in the virgin Lapua cases. It's good to learn from others' experiences. [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Hunting
Long Range Hunting & Shooting
Losing velocity...it's not the chrono..any ideas
Top