To Crimp or not to Crimp? That is the question.

[rod locker]

New to reloading.  2 different manuals read...one says to crimp pistol cartridges and the other says not to.  What should I do?  Shooting .38 Special, 158 lead bullet, 231 powder & Federal primers.  New to this and need the right advice please.

[Abilene]

What manual says not to crimp?  Every manual I've seen (haven't seen them all) says to crimp and I've never heard of anyone loading pistol cartridges without crimping.  Some buffalo rifle cartridges maybe.

[rickk]

Crimp and don't look back.

What manual says to not crimp? At the very least you need to remove the bell or it probably wont chamber.

A separate crimp die is a nice thing though... it saves lead shaving issues, which can lead to hard chambering. This is especially important if you aren't all that picky about trimming cases to uniform length regularly.

Crimping in general offers initial resistance to bullet movement, which allows the powder to start burning better, which improves accuracy. With "some" powders, if you don't crimp the powder simply won't ignite and you will get a squib load.... been there, done that.

If you are shooting a single shot rifle, and setting the bullet out to where it contacts the rifling when it chambers, maybe a crimp isn't so important, but you said Pistol Cartridges.

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[Delmonico]

Buy a seperate crimp die in a taper crimp and you'll even be happier, I'll never roll crimp another round in a caliber I can get a taper crimp in.

[wildman1]

Tried not crimpin in my 45/70 and couldn't get a 2' group at 100 yds. normally is pretty easy to get a 6" group at that distance even on a bad day. WM

[rickk]

The LEE "factory crimp" die is pretty cool for separate crimping operation.  No tools are required to adjust it... the big knurled knob can be turned by hand.

There is also a carbide base sizing ring in it, so in the event that anything went wrong and you dented or bulged a case in a prior operation, it will fix it when it crimps. I must admit, I have managed to dent a case or two in my life by not pushing the case completely into the shell holder before pulling the handle.

Rick

[Cliff Fendley]

If never seen a manual say not to crimp pistol ammo. Pistol seating dies are made to crimp for a reason.

Read again and make sure they were not talking about rifle cartridges.

[Delmonico]

The LEE "factory crimp" die is pretty cool for separate crimping operation.  No tools are required to adjust it... the big knurled knob can be turned by hand.

There is also a carbide base sizing ring in it, so in the event that anything went wrong and you dented or bulged a case in a prior operation, it will fix it when it crimps. I must admit, I have managed to dent a case or two in my life by not pushing the case completely into the shell holder before pulling the handle.

Rick

Yep, I was including the Lee die in with the taper crimps.  Often a roll crimp, if the case is slightly longer that the one the die was set up for will pull the case away from the sides of the bullet below the crimp.  this can cause chambering problems as well as a looser bullet fit.

If you want to see the difference load some dummy rounds both ways, us a good roll crimp and a good heavy taper crimp.  Take a kinetic puller and see which ones are harder to take back apart.

A tight bullet pull is needed in any round, whether crimped or not, this allows a better powder burn.   

[Shotgun Franklin]

I switched to a taper crimp very many years ago. Works great for me.
In my experience a crimp works well on all ammo. I've owned 2 Remington Rolling Blocks and they shot much better when the ammo was crimped.

[Tuolumne Lawman]

+1 on the LEE factory crimp die.  I have noticed with the .44-40, rifle cartridges were noticeably more accurate when zi used the LEE factory crimp die.  OAL on 38-40 and 44-40 cases is less critical with a crimp die as opposed to a roll crimp.

[Shotgun Franklin]

When I bought my first taper crimp die I was told that I'd never need to trim a case again. That has to have been 25 years ago, at least, so far it's been true.

[rod locker]

I bought a RCBS TC Carbide 3 die set.  It says it will do the taper crimp.  But the small pamplet I got with my Lyman loader said not to crimp if going for target or varmit loads.  I thought since shooting at targets only that I would not have to crimp.  But ya'll have convinced me otherwise.  Thanks for all the help.

[rickk]

Instructions can be funny sometimes.   They tend to have generic instructions that sometimes get thrown into every die set.

If you were shooting a bolt gun or single shot  (classic target or varmit rifle choices), there are reasons to consider not crimping.  The bullet is usually seated right up into the rifling so that the rifling itself helps build up pressure to get a good beginning of a burn.  There is a lot of thought that the accuracy is improved when there is no jump before the bullet engages the rifling.  At the same time the brass will last longer because it does not get worked excessively around the case mouth.  Also, the bullet does not get deformed during crimping if there is no crimp.  There are almost endless other reasons as well. If shooting a match rifle at targets a few hundred yards or more away, playing with such things matters. 

However, when they "play with" not crimping, they make other adjustments. Like I already mentioned, the bullets are often seated every long to engage the rifling. Powder selection is important as well some powders need to build up pressure to a certain minimum before the primer goes out or they will not burn. Magnum primers are often used too.  For instance, try some H110 in a .357 with standard primers and no crimp... on second thought, don't. I can save you the pain. You will get squib loads, hang fires, and plain ole duds.  Add a heavy crimp and things will work much better.

So, there is sometimes a reason not to crimp, but on a 38 in a revolver I am not seeing one.

[Delmonico]

I'm going to be brutally honest, calling a 38 special load made to hit a large metal target up close can hardly be called a "target load."

[Cliff Fendley]

I bought a RCBS TC Carbide 3 die set.  It says it will do the taper crimp.  But the small pamplet I got with my Lyman loader said not to crimp if going for target or varmit loads.  I thought since shooting at targets only that I would not have to crimp.  But ya'll have convinced me otherwise.  Thanks for all the help.

That pamphlet with your loader is probably referring too rifle ammo as target and varmint loads.

You will always crimp pistol ammo or ammo used in tubular magazines.

Generally if the die set is made to crimp then you need to crimp, whether you do it with the bullet seating die or a separate crimp die is up to you and the quality of ammo your wanting to produce.

Have fun reloading.

[bowiemaker]

Taper vs. roll crimp: why is one preferred over the other?

[Delmonico]

Generally if the die set is made to crimp then you need to crimp, whether you do it with the bullet seating die or a separate crimp die is up to you and the quality of ammo your wanting to produce.

Have fun reloading.

No a lot of bottle neck rounds are also set up to crimp if you desire.  My RCBS 243 dies will crimp if desired, a lot of folks choose a bullet with a crimp groove and crimp in rounds for semi-auto rounds besides lever gun rounds.

[Grapeshot]

Taper vs. roll crimp: why is one preferred over the other?

Roll crimps are generaly used in revolver ammo.  That being said, a good taper crimp will also work in non-magnum loads.

The taper crimp is for Auto-Pistol loading.  Reason for this is that auto pistol case headspaces on the case mouth.  Using a roll crimp may cause headspace problems or failure to chamber.

[cpt dan blodgett]

If shooting a pistol cartridge out of a rifle the rolled crimp may be necessary for one or both of two reasons.  Using a tube magazine the catridges bumb into each other on recoil.  If too lightly crimped bullets may be driven back into the case.  This can cause pressure problems but may not be an issue with wimpy CAS loads.

The second reason is some rifles will not chamber well if the front of the case is an abrupt sharp edge, roll crimping makes a nice smooth radius that will chamber more easily.

[Trailrider]

If shooting a pistol cartridge out of a rifle the rolled crimp may be necessary for one or both of two reasons.  Using a tube magazine the catridges bumb into each other on recoil.  If too lightly crimped bullets may be driven back into the case.  This can cause pressure problems but may not be an issue with wimpy CAS loads.
The second reason is some rifles will not chamber well if the front of the case is an abrupt sharp edge, roll crimping makes a nice smooth radius that will chamber more easily.

Unless you are dealing with a rimless pistol cartridge or a large bottlenecked rifle cartridge to be used in machineguns, ALWAYS roll crimp, unless the bullet does not have a crimp groove or a grease groove into which the roll crimp will project, or ahead of the front driving band on some rounds intended for use with a full case of black powder behind the bullet. Taper crimps are fine, and as you can see, some folks swear by them. But in my 50+ years of reloading, I have found that a roll crimp and a good interference fit of the bullet in the case neck improves ignition characteristics, especially with relatively slower-burning smokeless pistol rounds.  It was "common knowledge" for years that not crimping pistol rounds improved accuracy. NOT SO! A good roll crimp (or a taper crmp where required by a rimless case) improves ignition uniformity.  As was stated, a roll crimp will probably improve feeding in a repeating rifle.