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I'm suspicious about their "inadequate crimping". They refer to inadequate crimp being the cause for bullet movement. As far as I'm aware, you should have enough neck tension without crimp, if not something isn't right with your reloading.
If you need to apply crimp to fix the bullet in the case, then you probably crimp so hard that the bullet deforms.

If I remember correctly there is some post here on the forum of Iowegan giving some quantitative info on what the effect of crimp is....
 

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I'm suspicious about their "inadequate crimping". They refer to inadequate crimp being the cause for bullet movement. As far as I'm aware, you should have enough neck tension without crimp, if not something isn't right with your reloading.
If you need to apply crimp to fix the bullet in the case, then you probably crimp so hard that the bullet deforms.

If I remember correctly there is some post here on the forum of Iowegan giving some quantitative info on what the effect of crimp is....
It doesn't apply to all cartridges equally.

When you get into some of the 'bigger boomer' revolver rounds like 44 magnum, a sufficient crimp is required to hold the bullet in place during recoil for the rounds that haven't been fired yet. They can lock up a revolver if they get to be longer than the cylinder in length.

Using slower burning 'magnum' powders requires a bit stronger crimp as well to ensure a little bit of delay (measured in milliseconds) so the powder burns more completely.
 

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It doesn't apply to all cartridges equally.

When you get into some of the 'bigger boomer' revolver rounds like 44 magnum, a sufficient crimp is required to hold the bullet in place during recoil for the rounds that haven't been fired yet. They can lock up a revolver if they get to be longer than the cylinder in length.

Using slower burning 'magnum' powders requires a bit stronger crimp as well to ensure a little bit of delay (measured in milliseconds) so the powder burns more completely.
I'm definitely interested to hear more about this from various people. Because this sounds like balancing bullet-deformation (a very strong crimp) and thus accuracy with proper operation safety. This is clearly a matter of experience ... and thus perfect for this forum :)

I assume .357 magnum isn't a big enough boom for this to happen, because I never experienced any bullet forward movement in my reloads (and I don't crimp much).
 

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I assume .357 magnum isn't a big enough boom for this to happen, because I never experienced any bullet forward movement in my reloads (and I don't crimp much).
I have experienced bullet movement or pull in .357 mag when using plated bullets with no canellure and a light crimp. I no longer use plated bullets in magnum loading for this reason. Any crimp I've tried that is sufficient to hold the bullet under recoil also results in more bullet deformation than I care to accept. I have used a taper crimp to success with plated bullets in revolver cartridges when using medium to fast powders.
 

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I have experienced bullet movement or pull in .357 mag when using plated bullets with no canellure and a light crimp. I no longer use plated bullets in magnum loading for this reason. Any crimp I've tried that is sufficient to hold the bullet under recoil also results in more bullet deformation than I care to accept. I have used a taper crimp to success with plated bullets in revolver cartridges when using medium to fast powders.
I have done the same with light .38 spec. loads. Heavy .357 mag and up (.41, .44, .45, .480) loads with 4227, 110, 296, 400 etc. require a well formed roll crimp more than anything to get proper powder burning.
 

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A good reminder.
 

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excellent awareness article.! thank for sharing!
 

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Biartr, Crimping is one of my favorite reloading topics .... mostly because many people do not understand the concept. We tend to spend a lot more time discussing crimping than sizing, expanding, or bullet seating ... all of which are just as important.

Crimping for lead bullets versus crimping for jacketed bullets is like day and night .... not to mention crimping for plated bullets, which is different than either jacketed or lead.

Let's start with the dies ..... factory die sets for semi-autos come with a taper crimp die .... die sets for revolvers come with a roll crimp die. Most die sets include the crimp in the bullet seater die and are intended to be done in two different operations. The first operation is seating the bullet where the die body has been backed out and the seater stem has been adjusted so the die does not apply any crimp at all but does seat the bullet to the proper depth. A second pass with the seater stem backed out and the die body adjusted properly will apply the proper crimp and finish the process. If you have a progressive press like a Dillon, the die sets come with a dedicated bullet seater (no internal crimp) and a separate crimp only die .... making it necessary to have 4 stations.

Bullets: All lead bullets intended for straight wall revolver cartridges have a deep crimp groove. All jacketed bullets intended for a revolver will have a cannelure that serves much like a crimp groove only not as deep. Lead or jacketed bullets intended for semi-autos DO NOT have a crimp groove or cannelure ... just a smooth body.

Crimping for lead bullets with a crimp groove: The crimp mission is twofold .... remove the case mouth bell that was applied by the expander die and apply a roll crimp. The case mouth should roll into the deep crimp groove .... hard enough where the bullet will not pull out from recoil from a fired adjacent chamber in a revolver. You can apply a pretty hard crimp to lead bullets without any detrimental effects .... except the brass will wear out faster.

Crimping for jacketed bullets with a cannelure: The crimp mission is also twofold as noted above but is much more critical than when crimping a lead bullet. The reason is .... jacketed bullets are much harder so if you try to apply a hard crimp, chances are the case will bulge and you will end up with less neck tension than if you didn't crimp at all. When a case has been sized properly, about 90% of the neck tension that holds the bullet in place comes from the sizing die. The crimp adds another 10% plus it removes the flared mouth that was a product of the expander die. If you stop and think about it .... the downward pressure on the case walls applied by the crimp die will cause the case body to expand ... leaving the crimped area the only place holding the bullet. This process is often misunderstood so people tend to apply even more crimp to prevent bullet jump .... with is counterproductive. The "best crimp" on a jacketed bullet with a cannelure is a modest roll crimp where the case mouth barely rolls into the cannelure. Any crimp stronger will actually decrease neck tension ... not increase it.

Crimping for jacketed bullets with no cannelure: These bullets are intended for semi-autos but can be used in revolvers provided you use a taper crimp die. You may have to buy a dedicated taper crimp die but if you reload for other cartridges, you may already have one. As an example .... you can use non-cannelure jacketed bullets in a 45 Colt cartridge by using the taper crimp die from a 45 ACP. Likewise with a smooth bullet in a 38 or 357 ... just use a 9mm Luger taper crimp die. Never try to use a roll crimp on smooth bullets (no cannelure) because it will distort the bullet and will likely end up with less neck tension than with no crimp at all. Another very important issue is ... semi-auto ammo is intended to headspace on the case mouth so if you roll crimp a semi-auto cartridge, headspace will be excessive ... possibly to a point where the firing pin won't reach the primer .... but in all cases, accuracy will suffer.

Most plated bullets do not have a cannelure so they are intended for a taper crimp die. If you apply a harsh crimp, you will break through the plating and end up defeating the very purpose of a plated bullet ... which is to eliminate lead vapor and lead bore fouling. If your plated bullets DO have a cannelure, apply a very modest roll crimp ... being careful not to break through the plating.

The key to uniform neck tension is a combination of using the proper sizing die, using cases that are in good condition, trimming cases to a uniform length, and applying a proper crimp. Many people keep loading their cases until they see a split mouth or the primer pocket will no longer hold a primer. This is fine for "plinkin' loads" where accuracy is not paramount, however for optimum accuracy, a uniform neck tension is required. Why? Neck tension holds the bullet in place and delays bullet movement until the powder has a chance to fully ignite. When you chronograph loads with cases that have been loaded more than 3~4 times, you will see a much wider extreme velocity spread, which in turn causes groups to open up. Why? Each time a case is fired and resized, it work hardens; however not all cases age at the same rate so neck tension will vary considerably after 3~4 times fired, thus a different velocity. As the length of the case varies by more than .005", the crimp tension will also vary. It's wise to trim cases if you plan to use the ammo for competition.

Neck tension plays a significant roll in all semi-autos. It is not unusual for a bullet to break loose when the nose strikes the feed ramp and gets seated deeper. This can result in dangerously high chamber pressures .... high enough to Kaboom the gun, especially in 9mm and 40 S&W pistols. Further, when the slide or bolt slams home, it creates a situation much like a kinetic bullet puller. This is obviously not a good condition ... especially if you extract the live round and spill powder in the guts of your pistol. When a proper taper crimp has been applied .... chances are the cartridge will feed much better because it is NOT bulged from over crimping and the case mouth doesn't snag from under crimping.

Several years ago I made a neck tension tester. It is simply a Lee 45 Colt bullet seater die with a Ruger Blackhawk hammer spring installed. It turns out, this die can be adjusted for any cartridge from a 9mm to a 45 Colt and will apply about 45 pounds of force on the bullet nose. If you measure the COL before and after testing, it should be exactly the same. Any time COL is shorter after testing, it indicates there is not enough neck tension .... time to investigate.

Here's my neck tension tester:
 

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Back about 1982 I was living in Tampa and used the police range there (it was open to the public). I was shooting my BH with reloads I had made. At the time I had been reloading a few years. The 45LC was the first straight walled handgun cartridge I was making reloads for.
I was working up hunting loads for it using 260 gr JHP bullets. I wasn't paying much attention to the crimp I was applying as I never had to before.
The shooting session started off okay, I was shooting at 50 yards with a sandbag rest. On the second six rounds I was noticing some unburned powder in and around the cylinder. After removing the cartridges, I took the cylinder out and cleaned off the unburned powder. I then examined the remaining cartridges and they seemed okay.
After I put the cylinder back in, I loaded up the BH and continued shooting. I pulled the trigger and nothing seemed to happened. I waited about a minute and nothing happened. I then coked the hammer and pulled the trigger. The result was the bullet entered the barrel as expected and ran into the bullet that was stuck in the barrel from the previous cartridge.
The great design of the Ruger saved be from serious injury or death. The barrel bulged and the ejector flew off the barrel.
Needless to say that ended my shooting session for the day.
After that I went back to the building where you signed in and out and talked to the manager.
He inspected the remaining cartridges and noticed they didn't have very much of a rolled crimp. He asked my what powder I was using and I told him W296.
I followed him over to the reloading area where he setup a 445LC seating die and apied a heavy roll crimp to the remaining cartridges.
After he finished, he got is BH 45LC went out and fired six rounds. Everything worked.
I took my broken BH to a local gunsmith where he installed a new barrel, front sight and ejector. He also hard chromed the revolver. I still have it and shoot it regularly. I hunted deer with it when I lived in Ohio as you can't hunt deer there with rifles.
From then on, I have always focused on applying a solid rolled crimp to all of my straight walled rimmed cartridges.
 

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Iowegan, thanks again for taking the time to write down your knowledge. A good thing to remember is indeed using taper crimp for non-cannelure bullets in revolvers as revolver die-sets typically come with roll crimp dies.

Reading all this, I've checked my .357M reloads and indeed COL enlarged. The largest displacement that I measured was .008 inch on the 6th round after having fired the 5 others. A new point of attention :) (although this .008" isn't affecting accuracy, safety or functioning)
 

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Biartr, With your 357 Mag bullet pulling situation ....If COL gets so long that the bullet nose extends from the cylinder face, you will sure know it. Also, you risk a squib load if you are using slow burning powder. No doubt you have a minor crimp problem. As you know, the best condition is to shoot 5 and have the 6th the same length as when first loaded.

Here's some possible causes .... it pretty much has to be one or more of these: You may be applying too much crimp, which causes the case to expand and actually reduces neck tension. If you use Lee "factory crimp" dies, they are notorious for squeezing the case against the bullet (post sizing). When the cartridge exits the die, the brass case expands but the bullet doesn't ..... leaving you with poor neck tension. You may not be applying enough crimp or your cases may be work hardened (reloaded too many times). Last, you are loading too hot or you may be using "heavy for caliber" bullets .... meaning something heavier than 158gr. If it is an ammo issue, it has to be one of these problems. Of course if the revolver is way too light, it's just a matter of recoil versus the weight of the gun.

I see Belgium is in the news again ... more terrorists. I hope you are safe!
 

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You may not be applying enough crimp
I'm pretty sure that's the problem. I have been crimping to just remove case flare. I don't have a .357/9mm taper crimp die yet and I've only been able to get bullets without cannelure around here (plated).
I'll try with my roll-crimp die just as a test, if it doesn't affect accuracy, it's a temp solution.

If you use Lee "factory crimp" dies, they are notorious for squeezing the case against the bullet (post sizing). When the cartridge exits the die, the brass case expands but the bullet doesn't ..... leaving you with poor neck tension.
Interesting. You know I do run Lee equipment (I do have my financial limits unfortunately), so this could also be part of the issue.
I'l make sure to buy another brand of taper crimp die. Should be carbide though, I'm not going to start lubing cases for a single die.

Of course if the revolver is way too light
I'm confident that is not the problem with my 6" Colt King Cobra :) If I'm out of bullets the thing can perfectly serve as a club.

I'm surely going to run the same experiment with factory ammo, the .008" bullet movement I have measured is rather small and considering other tests that I have done in my 1911 with bullet-setback of factory ammo, I wouldn't risk to bet on seeing no bullet shift in factory ammo.


I see Belgium is in the news again ... more terrorists. I hope you are safe!
Thanks, we should be fine here on the country-side. To be honest, I think chances are high that something happens in one of the EU capitals tonight... I sure hope not.
 

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Biartr,
Interesting. You know I do run Lee equipment (I do have my financial limits unfortunately), so this could also be part of the issue.
I'l make sure to buy another brand of taper crimp die. Should be carbide though, I'm not going to start lubing cases for a single die.
Perhaps I have confused you .... Lee carbide sizer dies are OK ... pretty much the same as other brands of carbide sizer dies. Likewise with their expander die and bullet seating die. The problem is the full length post sizing operation done in the crimp die (FCD). Lee does use a carbide ring in their "factory crimp die" but as far as I know, Lee is the only brand to use a post sizer in the crimp die. All other brands use a standard steel die ... not carbide. You don't have to lube cases for the crimp die ... only the sizer die if it is not carbide.

Post sizing means the full body of the cartridge is sized after a bullet has been seated and crimped. The FCD crimps on the down stroke and full length sizes on the upstroke. This can be a significant issue ... especially for lead bullets or plated lead bullets because the lead is soft enough to get squished smaller by the post sizer yet the brass case will literally spring back after being post sized. This results in very poor neck tension ... not enough to hold the bullet during initial powder ignition and not enough to keep the bullet from jumping forward when an adjacent chamber is fired.
 

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Iowegan, thanks. I was not confused, I had understood your main point, my comment about the lubing was simply wrong.
Although you previous post implied that it is not the case, I was wrongly assuming other brands would also have a full length sizer function in their crimp dies, which would require lube if steel.

Thanks for the patience when explaining, it has been very educational.
 

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I can appreciate the 'Bullets Seated Too Far Out'. When I first got my 7mm08 Model Seven in the late '80s, I was working up some hunting loads for it. I was marking the bullets and seating them out toward the rifling. After touching the rifling, I seated the subsequent bullets in just a hair and shot them at the range. Great accuracy, but when I tried to load them in the rifle's magazine... Uh, ooops! Too long!

The article doesn't really cover 'skipped/missing powder charge'. I was a victim of that and a second bullet propelled into a squib load bullet lodged in the barrel. That was 25 years ago, and has always stuck in my brain since. Nothing like the cost of a new barrel and shipping costs to the factory to remind you to always check all cases before seating bullets and to check the bore after an 'unusual' shot.
 
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