crimp
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Fine Figure of a Man
Member
I eyeball it then shoot over the crony. If the numbers are good I'm satisfied.
JohnhenrySTL
Member
I consider too much crimp for my .357 when the jacket starts to crumple on the bullet. Sometimes I get some jacket dust, but I like a fairly heavy crimp. I get consistent velocities with H110. None of my crimps have ever appeared as heavy as factory crimps. And I would crimp a bullet with a crimp groove as I call it more than one without.
.357 and .44 are typically roll crimped into a cannelure or crimp groove. I don't think you can measure that with a caliper. I just eyeball mine.
People do measure taper crimps, which are generally used on cartridges shot in auto pistols. A caliper works fine there.
People do measure taper crimps, which are generally used on cartridges shot in auto pistols. A caliper works fine there.
Hondo 60
Member
I don't know how you'd measure a roll crimp.
It's part of the "art" of reloading.
Do a Google search of images of a roll crimp & follow that lead.
Sorry there is no definitive answer.
Welcome to thr
It's part of the "art" of reloading.
Do a Google search of images of a roll crimp & follow that lead.
Sorry there is no definitive answer.
Welcome to thr
JohnhenrySTL
Member
I consider too much crimp for my .357 when the jacket starts to crumple on the bullet. Sometimes I get some jacket dust, but I like a fairly heavy crimp. I get consistent velocities with H110. None of my crimps have ever appeared as heavy as factory crimps. And I would crimp a bullet with a crimp groove as I call it more than one without.
Swampman
Old Fart
The amount of crimp needed will vary with the loads used. Dense, hard to ignite ball powders like W296/H110 require more crimp to get good ignition and uniform velocities.
This works out well in a practical sense since those powders usually give more recoil, and preventing bullets from jumping out of the case and tying up the cylinder is another important function of the crimp.
The bullet doesn't actually jump, inertia just tends to make it remain stationary and the gun and cartridge case recoil away from it unless the bullet is secured by a heavy roll crimp.
A lighter load with a powder like Trail Boss or Red Dot doesn't generally require a heavy crimp since they're easier to ignite and produce much less recoil.
A heavy crimp with light loads isn't needed, but it won't really hurt anything except your case life. The more you "work" your brass, the sooner it'll develop case mouth splits and need replacement.
The proper amount of crimp to use is, "Enough", plus whatever extra it takes to ensure reliable function under adverse conditions and maintain your confidence in the weapon.
Taper "crimps" in an auto cartridge are a lot easier to quantify and measure, roll crimping revolver rounds (particularly with cases that have been loaded multiple times) is almost more art than science.
Just remember, it's far better to err by over crimping than under crimping while you're learning (as long as you don't totally collapse your case walls to the extent that they won't chamber).
I have seen people do some incredibly stupid, dangerous things while trying to "fix" a tied up revolver.
This works out well in a practical sense since those powders usually give more recoil, and preventing bullets from jumping out of the case and tying up the cylinder is another important function of the crimp.
The bullet doesn't actually jump, inertia just tends to make it remain stationary and the gun and cartridge case recoil away from it unless the bullet is secured by a heavy roll crimp.
A lighter load with a powder like Trail Boss or Red Dot doesn't generally require a heavy crimp since they're easier to ignite and produce much less recoil.
A heavy crimp with light loads isn't needed, but it won't really hurt anything except your case life. The more you "work" your brass, the sooner it'll develop case mouth splits and need replacement.
The proper amount of crimp to use is, "Enough", plus whatever extra it takes to ensure reliable function under adverse conditions and maintain your confidence in the weapon.
Taper "crimps" in an auto cartridge are a lot easier to quantify and measure, roll crimping revolver rounds (particularly with cases that have been loaded multiple times) is almost more art than science.
Just remember, it's far better to err by over crimping than under crimping while you're learning (as long as you don't totally collapse your case walls to the extent that they won't chamber).
I have seen people do some incredibly stupid, dangerous things while trying to "fix" a tied up revolver.
Good advise swampman..
Here is a thread with some pics of some crimps.
Here is a sample from the thread:
Magtech 240 Gr JSP's in Hornady and FC range brass.
Here is a thread with some pics of some crimps.
Here is a sample from the thread:
Magtech 240 Gr JSP's in Hornady and FC range brass.
41 Mag
Member
Like mentioned you really usually only need enough to hold the bullet in place under recoil. When I work up loads and find something I like I usually run two cylinders of five rounds while measuring the sixth after each shot. If it moves more than about .003" during that process I add a smidge more crimp then repeat the process. I'm also looking at accuracy as well. Sometimes with some bullets the amount of crimp can make or break the load. Might have to piddle with a charge weight one way or another but usually it'll all fall in line together.
Lots of logical info above. Roll crimping is very difficult to measure with home reloader's tools, so, the best way is "eyeballing". Find a factory round that uses a similar bullet to what you're using and compare your crimp to the factory crimp. This will get you started with a decent crimp without crimping too much...
Walkalong's pics are a good example, but a side by side comparison with a "standard" will help quite a bit.
Walkalong's pics are a good example, but a side by side comparison with a "standard" will help quite a bit.
I roll crimp my 45 Colt, .357 Mag, the method I use is to start slow, gradually increase crimp until the bullet no longer spins in the case. You should not be able to move the bullet in any direction. When you are at this point, quit. You have the crimp set to the minimum but effective.
Good Luck
Dan
Good Luck
Dan
Sunray
Member
You don't measure either kind of crimp. The correct amount is, "Enough to hold the bullet in place under recoil and no more." Usually just enough to take out the flare and no more works.
A crimp isn't always required either. It's only required for hot loads in heavy recoiling cartridges and on ammo used in a lever action.
A taper crimp you can see. About 1/16" long/wide taper is plenty.
A crimp isn't always required either. It's only required for hot loads in heavy recoiling cartridges and on ammo used in a lever action.
A taper crimp you can see. About 1/16" long/wide taper is plenty.
Wait, until crimping, your bullets spin in the cases? Man, that doesn't sound like much tension at all.
Swampman
Old Fart
If you're sizing and belling your cases properly, they should be held in place pretty firmly by case neck tension alone. If the bullet spins or moves in and out of the case mouth easily, you've got issues that shouldn't be addressed solely by crimping.
That post will do nothing but confuse and mislead people that are trying to learn.
"You don't measure either kind of crimp"
YOU may not, but most reloaders will measure taper "crimps" while they're setting up their dies.
"Usually just enough to take out the flare and no more works."
This would be good advice if the OP's question were about reloading 9mm or .45 ACP. It's very poor advice to someone asking about how to set crimp for the .44 or .357 Magnums.
"A taper crimp you can see. About 1/16" long/wide taper is plenty."
No.
You may well be able to see a roll crimp, but if you can see a taper crimp, you've probably overdone it. In most cases, all you see with a properly applied taper crimp is that the belling is gone and the outside of the case is more or less straight.
If you cn see a 1/16th inch band where the taper crimp was applied, you've over crimped.
for a 357, or 44 magnum, the case mouth should be crimped to the bottom of the cannelure. per walkalong's post above, use a magnifying glass (at least 4x) and visually check. you will know if you overdo it if you get a nice shinny ring of brass sheared off the case mouth by the seating die.
luck,
murf
luck,
murf
Agreed.
Virginia Jim
Member
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Question:
If the cases are not equal length, would not the amount of roll crimp vary?
If the cases are not equal length, would not the amount of roll crimp vary?
Swampman
Old Fart
Absolutely.
Keeping roll crimps uniform requires that all cases be of the same length.
Yes, which is why I trim revolver cases unless they are all the same brand/batch and are very consistent in length. The question is not if it affects a consistent roll crimp, it does, but if it affects it enough to matter. Some folks never trim revolver cases. I have tired shooting trimmed vs untrimmed cases and I am not good enough to shoot the difference. Are some people good enough? I bet there are.
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