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October 16th, 2024
Here’s a smart tip from Bryan Litz, explaining how damage to a bullet jacket can harm the projectile’s Ballistic Coefficient (BC). This tip is posted on Bryan’s new Bryan Litz Ballistics Facebook page. We recommend you subscribe to that page to access Bryan’s latest informative posts.
Bryan notes: “If the case mouth scratches the bullet when you seat it, the damage can cause the BC to be inconsistent, which shows up as vertical dispersion at long range.”
We see this sometimes when running Doppler Radar for competitors at Applied Ballistics Mobile Lab events. If someone is shooting a bullet that typically has a very consistent BC (1% or less) but they’re seeing a higher BC variation, it can be due to the bullets being damaged in the loading process.”
The lead photo above shows the badly-scratched jacket of a bullet seated in a rough-mouthed case. To prevent such jacket damage, one should chamfer, deburr, and smooth case mouths after trimming.
Below is a recorded Doppler radar result showing excessive BC variation. Such variation can increase vertical dispersion at long range. This can result in larger group sizes and lower scores.
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September 21st, 2023
Here’s a smart tip from Bryan Litz, explaining how damage to a bullet jacket can harm the projectile’s Ballistic Coefficient (BC). This tip is posted on Bryan’s new Bryan Litz Ballistics Facebook page. We recommend you subscribe to that page to access Bryan’s latest informative posts.
Bryan notes: “If the case mouth scratches the bullet when you seat it, the damage can cause the BC to be inconsistent, which shows up as vertical dispersion at long range.”
We see this sometimes when running Doppler Radar for competitors at Applied Ballistics Mobile Lab events. If someone is shooting a bullet that typically has a very consistent BC (1% or less) but they’re seeing a higher BC variation, it can be due to the bullets being damaged in the loading process.”
The lead photo above shows the badly-scratched jacket of a bullet seated in a rough-mouthed case. To prevent such jacket damage, one should chamfer, deburr, and smooth case mouths after trimming.
Below is a recorded Doppler radar result showing excessive BC variation. Such variation can increase vertical dispersion at long range. This can result in larger group sizes and lower scores.
Share the post "Scratches on Bullet Jackets Affect BC and Long Range Accuracy"
August 4th, 2023
 Shoot 101 Quiz
How much of an expert are you when it comes to firearms and ballistics? Test your knowledge with this interactive test. Guns & Ammo magazine created a series of features called Shoot 101. These articles provide “how to” information about shooting, optics, and outdoor gear.
On the Guns & Ammo website, you’ll find the Shoot 101 Ballistics Quiz. The 15 questions are pretty basic, but it’s still fun to see if you get all the answers correct.
You don’t need a lot of technical knowledge. And it’s not all about flight ballistics. Roughly a third of the questions are about projectile types and bullet construction. Note, for some reason the layout doesn’t show all the possible answers at first. So, for each question, be sure to scroll down using the blue scroll bar on the right.
Sample Ballistics Question
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March 22nd, 2022
Here’s a smart tip from Bryan Litz, explaining how damage to a bullet jacket can harm the projectile’s Ballistic Coefficient (BC). This tip is posted on Bryan’s new Bryan Litz Ballistics Facebook page. We recommend you subscribe to that page to access Bryan’s latest informative posts.
Bryan notes: “If the case mouth scratches the bullet when you seat it, the damage can cause the BC to be inconsistent, which shows up as vertical dispersion at long range.
We see this sometimes when running Doppler Radar for competitors at Applied Ballistics Mobile Lab events. If someone is shooting a bullet that typically has a very consistent BC (1% or less) but they’re seeing a higher BC variation, it can be due to the bullets being damaged in the loading process.”
The lead photo above shows the badly-scratched jacket of a bullet seated in a rough-mouthed case. To prevent such jacket damage, one should chamfer, deburr, and smooth case mouths after trimming.
Below is a recorded Doppler radar result showing excessive BC variation. Such variation can increase vertical disperson at long range. This can result in larger group sizes and lower scores.
Share the post "BC Variance from Bullet Jacket Damage Can Increase Vertical"
August 28th, 2019
Shoot 101 Quiz
How much of an expert are you when it comes to firearms and ballistics? Test your knowledge with this interactive test. Guns & Ammo magazine created a series of features called Shoot 101. These articles provide “how to” information about shooting, optics, and outdoor gear.
On the Guns & Ammo website, you’ll find the Shoot 101 Ballistics Quiz. The 15 questions are pretty basic, but it’s still fun to see if you get all the answers correct.
You don’t need a lot of technical knowledge. And it’s not all about flight ballistics. Roughly a third of the questions are about projectile types and bullet construction. Note, for some reason the layout doesn’t show all the possible answers at first. So, for each question, be sure to scroll down using the blue scroll bar on the right.
Sample Ballistics Question
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April 17th, 2012
Shaving bullet jackets is a problem reloaders encounter from time to time. It can be caused by excessive neck tension, burrs on the case mouth, or over-aggressive chamfering that leaves a ragged edge on the case mouth. Larry Medler discovered some rounds where the bullet jackets were getting shaved. Diagnosing the problem, he found that this was caused by his outside neck chamfer. He was using a powered screwdriver to rotate the case, and over-cutting plus tool chatter was causing the case neck to roll inwards. This created a thin, sharp edge that actually cut into the bullet jacket as the bullet was being seated.
 
Larry has a Load Force 250 measuring instrument that records the dynamic bullet seating force and displays the results on a computer screen. Larry noted that spikes in seating force were associated with the cases where the bullets were shaved. Inspecting the cases, Larry realized what was happening. Chamfering the outside after doing the inside allowed his tools to cut too much. Combined with tool chatter, this actually created a sharp, ragged edge that rolled inward towards the bullet: “I discovered I had rolled the case mouth rim inward while deburring the outer edge. When deburring the case mouth on the outside edge, every now and then I could hear some tool chatter. The effects of this chatter really show in the picture.”
The above chart shows the dynamic bullet seating force for the bullet with the shaved jacket. Note the large initial force used to cut and scratch the bullet outer surfaces. The final seating force of 47 pounds is just before the Wilson Seating Die bottoms out and the force on the load cell jumps. The chart below shows normal bullet seating force.
As a fix, Larry decided to reverse the neck deburring operations. Now he deburrs the outside first. This reduces tool chatter and prevents the edge from rolling over, because the neck thickness has not been thinned by inside chamfering. While Larry uses a powered screwdriver to speed his case processing, the lesson applies to those who chamfer manually as well–do the outside first and never overcut.
Remember, you simply want to remove burrs and create a slight chamfer. You don’t want to thin the brass significantly at the case mouth. This is why it is important to be very careful when using a deep-angle cutter such as the K&M inside neck chamferer. Click HERE to read Larry’s full report on neck chamfering, with more details on use of the Load Force 250 measuring instrument. Using device such as this, or a K&M arbor press equipped with a seating force gauge, will help you diagnose problems with your neck tension and reloading procedures.
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