The only bullets I ever crimped in the first 40 years of reloading were magnum revolver rounds loaded with heavy bullets, in high recoiling cartridges. Crimps are mandatory in this sort of ammo.
About 7 years ago I purchased an AR15. One year ago I began a fairly exhaustive internet search on crimping handloaded AR15 ammunition. There's a lot of varying opinions expressed on this topic, and for the most part, the posters sounding in have never crimped any ammo, yet they profess to KNOW the best option. So I'll not spend a single sentence debating preferences with anyone on this Forum.
I'll simply share a little of my research, the results of my limited testing, and more significantly, the much more extensive test results of another local shooter's experiences.
My internet research:
I found many Posts supporting crimping on a variety of forums from some individuals with a lot of experience crimping rifle ammo. Not just for their AR15s, but also for bolt action rifles. Virtually without exception, those crimping their rifle ammo recommended using the Lee Factory Crimp Die.
I found that the majority of those posting against crimping rifle ammo, when push came to shove, had to admit they'd never even tried it once in their entire life of reloading. Which meant all they were doing was babbling non-expert opinions.
I eventually located a fairly extensive set of "test" data, comparing Lee Factory Crimp Die" crimped handloads, to the same exact handloads without the crimp. The author tested three different cartridges in three different rifles with three different bullets per cartridge, as I recall. One was in .223 rem, and the other two were bolt action rifles in larger calibers, one being .308. The author/tester also chronographed every shot fired. He collected both accuracy data and MV/ES/SD data for each round/rifle tested. Did a very nice job presenting the results of his testing. With every round tested, the crimped ammo shot more accurately. Crimping didn't seem to have much effect on MV/ES/SD. The value of crimping did show in improved accuracy. More so with the .223 ammo than with the two larger caliber cartridges.
So I purchased my first Lee Factory Crimp Die in .223 Rem, convinced it was unlikely to degrade accuracy in my AR15, and that it would improve function reliability in my AR15. I had already spent some time on load development, so I crimped some of my handloads and headed out to test accuracy and MV/ES/SD of the crimped ammo versus the exact same loads with no crimp at 280 yds.
My Testing:
Photo of No-Crimp target/accuracy:
Photo of Crimped target/accuracy:
I was shooting 60gr Hornady Vmax bullets, which have no crimping cannelure. I continued crimp versus no-crimp testing with three differing crimp levels; light, medium, and heavy. None of the crimps I applied would have significantly indented the bullet. But I will state that I never pulled a single crimped bullet to see if I could feel and measure any level of indentation. All three crimping levels improved accuracy, and the heaviest level of crimp proved to yield a little better accuracy than the lighter crimped rounds. Both of the above targets consist of six shots fired. Ignore the additional shots on the no-crimp target and just look at the ink line circle enclosing the six rounds of crimped ammo versus the six rounds of no-crimp ammo.
I recorded MVs for each round fired over my triplicate chronographs, which provide 4 separate recorded bullet velocities for each bullet. I expected to see an improved MV precision (reduced ES), but I really didn't see that.
So I showed these to targets at my local gun shop to a guy that likely owns more than 100 firearms. Retired from more than 30 years in law enforcement, and additional years duty on security jobs protected local industrial factories. He began hunting at less than 10 years old, harvesting deer for his family to eat. He shoots continually and he's a very good shot. He's not into long range shooting, but he's shooting a rifle more days than not, and keeps a ledger for every load tested. He interest was piqued, and he said he did crimp for his semi-auto AR15s and other semi-auto rifles, but rarely for bolt action rifles. About one month later I found the testing article during continued internet research and I read it twice and studied the data more than that. I printed the article out and took it to the gun shop and showed it to this shooter. He looked it over and I described the findings. The testing was completed and the article printed, about 10 years ago. I offered to give the printed article to him, but after reviewing it, he handed it back to me. I suppose he doesn't trust anyone and anything more than his own experiences and experiments.
My fellow-shooter's testing:
About 4-5 weeks later I'm in the gun shop and this shooter tells me he's tested crimped rounds in at least six rifles, and in no instance did accuracy degrade. Without exception, accuracy was at least as good as without the crimp, and improved accuracy was very notable with some rifles/cartridges. He's absolutely convinced that crimping with the Lee Factory Crimp Die improves accuracy compared to his same accuracy loads without any crimp. None of his reloaded ammo is loaded with the bullets jammed into the lands. He's obtained a Lee Factory Crimp Die for every factory round he owns/shoots. And he's disappointed that he can't find them available for his wildcat cartridges. I told him that perhaps the gunsmith could use a chamber reamer to create a Lee Factory Crimp Die collet for his wildcats using the factory version of the wildcatted cartridge. He said he may look into that.
This guy is as blunt and honest in his assessment of things shooting and reloaded related as they come. He often carries his written ledgers containing his load data into the gun shop with just fired targets from the range. The gunsmith has re-barreled at least 20 of his rifles over the years.
I asked if he was testing bullets with cannelures and he said both. So he tested both types of bullets. His testing wasn't performed on random reloads. He used the same accuracy loads he's developed over the years and then simply crimped some of those cartridges and shot them side by side with no crimp ammo.
Take it or leave it.
Many target shooters jam their bullets into the lands. I believe this helps consistency of powder ignition rate and powder burn rate, which improves on target accuracy. Many hunters don't jam their bullets into the lands. Especially hunters like my fellow-shooter that don't pursue long range hunting and long range shooting. For those shooting less than 400 yards, the gain in accuracy by jamming bullets isn't worth the risk of reduced cartridge feed and extraction reliability in the field. Especially when the brown and black bears are ever present.
About 7 years ago I purchased an AR15. One year ago I began a fairly exhaustive internet search on crimping handloaded AR15 ammunition. There's a lot of varying opinions expressed on this topic, and for the most part, the posters sounding in have never crimped any ammo, yet they profess to KNOW the best option. So I'll not spend a single sentence debating preferences with anyone on this Forum.
I'll simply share a little of my research, the results of my limited testing, and more significantly, the much more extensive test results of another local shooter's experiences.
My internet research:
I found many Posts supporting crimping on a variety of forums from some individuals with a lot of experience crimping rifle ammo. Not just for their AR15s, but also for bolt action rifles. Virtually without exception, those crimping their rifle ammo recommended using the Lee Factory Crimp Die.
I found that the majority of those posting against crimping rifle ammo, when push came to shove, had to admit they'd never even tried it once in their entire life of reloading. Which meant all they were doing was babbling non-expert opinions.
I eventually located a fairly extensive set of "test" data, comparing Lee Factory Crimp Die" crimped handloads, to the same exact handloads without the crimp. The author tested three different cartridges in three different rifles with three different bullets per cartridge, as I recall. One was in .223 rem, and the other two were bolt action rifles in larger calibers, one being .308. The author/tester also chronographed every shot fired. He collected both accuracy data and MV/ES/SD data for each round/rifle tested. Did a very nice job presenting the results of his testing. With every round tested, the crimped ammo shot more accurately. Crimping didn't seem to have much effect on MV/ES/SD. The value of crimping did show in improved accuracy. More so with the .223 ammo than with the two larger caliber cartridges.
So I purchased my first Lee Factory Crimp Die in .223 Rem, convinced it was unlikely to degrade accuracy in my AR15, and that it would improve function reliability in my AR15. I had already spent some time on load development, so I crimped some of my handloads and headed out to test accuracy and MV/ES/SD of the crimped ammo versus the exact same loads with no crimp at 280 yds.
My Testing:
Photo of No-Crimp target/accuracy:
Photo of Crimped target/accuracy:
I was shooting 60gr Hornady Vmax bullets, which have no crimping cannelure. I continued crimp versus no-crimp testing with three differing crimp levels; light, medium, and heavy. None of the crimps I applied would have significantly indented the bullet. But I will state that I never pulled a single crimped bullet to see if I could feel and measure any level of indentation. All three crimping levels improved accuracy, and the heaviest level of crimp proved to yield a little better accuracy than the lighter crimped rounds. Both of the above targets consist of six shots fired. Ignore the additional shots on the no-crimp target and just look at the ink line circle enclosing the six rounds of crimped ammo versus the six rounds of no-crimp ammo.
I recorded MVs for each round fired over my triplicate chronographs, which provide 4 separate recorded bullet velocities for each bullet. I expected to see an improved MV precision (reduced ES), but I really didn't see that.
So I showed these to targets at my local gun shop to a guy that likely owns more than 100 firearms. Retired from more than 30 years in law enforcement, and additional years duty on security jobs protected local industrial factories. He began hunting at less than 10 years old, harvesting deer for his family to eat. He shoots continually and he's a very good shot. He's not into long range shooting, but he's shooting a rifle more days than not, and keeps a ledger for every load tested. He interest was piqued, and he said he did crimp for his semi-auto AR15s and other semi-auto rifles, but rarely for bolt action rifles. About one month later I found the testing article during continued internet research and I read it twice and studied the data more than that. I printed the article out and took it to the gun shop and showed it to this shooter. He looked it over and I described the findings. The testing was completed and the article printed, about 10 years ago. I offered to give the printed article to him, but after reviewing it, he handed it back to me. I suppose he doesn't trust anyone and anything more than his own experiences and experiments.
My fellow-shooter's testing:
About 4-5 weeks later I'm in the gun shop and this shooter tells me he's tested crimped rounds in at least six rifles, and in no instance did accuracy degrade. Without exception, accuracy was at least as good as without the crimp, and improved accuracy was very notable with some rifles/cartridges. He's absolutely convinced that crimping with the Lee Factory Crimp Die improves accuracy compared to his same accuracy loads without any crimp. None of his reloaded ammo is loaded with the bullets jammed into the lands. He's obtained a Lee Factory Crimp Die for every factory round he owns/shoots. And he's disappointed that he can't find them available for his wildcat cartridges. I told him that perhaps the gunsmith could use a chamber reamer to create a Lee Factory Crimp Die collet for his wildcats using the factory version of the wildcatted cartridge. He said he may look into that.
This guy is as blunt and honest in his assessment of things shooting and reloaded related as they come. He often carries his written ledgers containing his load data into the gun shop with just fired targets from the range. The gunsmith has re-barreled at least 20 of his rifles over the years.
I asked if he was testing bullets with cannelures and he said both. So he tested both types of bullets. His testing wasn't performed on random reloads. He used the same accuracy loads he's developed over the years and then simply crimped some of those cartridges and shot them side by side with no crimp ammo.
Take it or leave it.
Many target shooters jam their bullets into the lands. I believe this helps consistency of powder ignition rate and powder burn rate, which improves on target accuracy. Many hunters don't jam their bullets into the lands. Especially hunters like my fellow-shooter that don't pursue long range hunting and long range shooting. For those shooting less than 400 yards, the gain in accuracy by jamming bullets isn't worth the risk of reduced cartridge feed and extraction reliability in the field. Especially when the brown and black bears are ever present.
