Can You Over-Crimp A Revolver Load?

[GypsmJim]

I always roll crimp lead bullets in the crimping groove using the bullet seating die (Lee dies). I rarely break down loaded cases. Today, after my final inspection, I had two .357 Magnum rounds that I had to pull and replace deformed bullets that I missed when I originally cast them. My inertial puller had to be pounded and pounded to get the bullets to pull. I can't ever remember having to pound so hard to get a bullet to come out!

When I loaded them the die was set about 1/2 to 3/4 turns in to form the crimp. It visually didn't look too heavy - more like I have done hundreds of times before.

My question is....are there consequences to crimping TOO hard?

 

[Mistered]

My question is....are there consequences to crimping TOO hard?

Often wondered the same thing myself - Speer # 9 says a 'Firm' roll crimp - Hmm what is 'Firm' ? I can only say my crimps only feel like a slight 'hesitation' on the handle of the press and have a smooth appearance and are not 'bulged' out. Lets see what others have to say.

 

[GypsmJim]

I have never had a bulging problem. My cases are smooth and they chamber perfectly.

 

[Nighthawk0083]

One reason not to over crimp brass is it shortens the life of the brass. Some dies may crush cases if alot of force is necessary to put a real heavy crimp.

 

[Mistered]

Basically my crimps 'fill' the groove of the bullet and do not actually 'grip' it.

 

[ageingstudent]

Welll too much crimp doesn't do your brass any favors in the longevity department. The mouth of the case gets work hardened from excessive flaring and crimping and susceptible to splits sooner in my experience. I usually like to set the crimp a little light and work it down until it just rolls the case mouth into the cannelure snug against the projectile, but not biting in. If it takes whacks with the bullet puller much harder than I think the recoil of the gun will be I lighten it up a bit. By fussing with it I've learned that you don't feel as much pressure on the press as you think you might to get a decent crimp.

I have not had an issue (yet) where a too hard crimp affected anything negatively that I could tell, but then I usually don't crimp any more than necessary. I have had a couple loads in .357 perform better when I snugged the crimp a little tighter with a slower powder. Hs6 and 4227 come to mind.

 

[rwsmith]

Well, buckling the case isn't good.....

..... and if the crimp appears to be doing more damage to the case mouth than adding to the crimp, it's too much. If you don't go below minimum loads you stand very little chance of crimping so hard the bullet doesn't leave the barrel. In fact, a stronger crimp might actually help build more pressure before the bullet is released, which may help consistent burn of each round.

 

[colt_saa]

My question is....are there consequences to crimping TOO hard?

If you are using a plated or coated projectile, over crimping with a ROLL Crimp can cut through the plating or coating

There is little to no danger of this if you are using a TAPER Crimp or a COLLET Crimp (sometimes called a STAB Crimp)

Over crimping is a moot point if the projectiles are Lead or Jacketed

The biggest reason to lightly crimp your hand loads is to extend the life of the cartridge

 

[fredj338]

Yes you can over crimp, roll or taper. Over Crimping can damage the bullet as well as bulging the case. Over crimping can also cause loss of neck tension if you get any case bulge.

 

[Wise_A]

Overcrimping with any crimp style can damage the bullet and inhibit accuracy. You've got a press capable of delivering massive force--do you really think that a lead bullet or lead core can stand up to it without being deformed?

When I loaded them the die was set about 1/2 to 3/4 turns in to form the crimp. It visually didn't look too heavy - more like I have done hundreds of times before.

Depending on the load, it might be.

At .38 Spl, my crimps are in the 1/4-1/2 range for light loads. .44 Magnum at full power, more like a full turn.

But that's neither here nor there, because it's dependent on the bullet, the case, the dies, etc.

When you pulled the bullets, were they damaged or deformed? Is your ammunition inaccurate? If the answer to both questions was "no", then your crimp is likely fine.

 

[rockquarry]

Too much crimp can cause bullet distortion which can destroy accuracy.

"Crimp" is a relative term and doesn't meant the same thing to everyone. I've never seen a need for what I would call a "heavy" crimp, even on a .44 Magnum cartridge.

Regardless of the type of crimp used, the degree of crimp should be sufficient to insure proper ignition and to keep a bullet from moving under recoil and no more.

 

[ggibson511960]

Why Worry?

There are so many un-measureable and non-linear variables that it's not worth worrying about if acccuracy, perceived pressure, and case life are O.K., whatever that means, and bullets are staying put in the case. Loading manuals and powder companies admonish heavy crimps for slow burning powder, but how can you possibly quantify the practice? I try to make them look like factory rounds and forget it. Years ago I read of a reloader who set up a pull force fixture to test his ammo. I guess it was worth it to him, but one would have to use these results on a uniform batch of brass. Every firing-reloading cycle changes the materials modulus of the brass.

 

[rwsmith]

I saw an article some years back....

.....that showed that the latest method of crimping flattened the mouth of the case into the cannelure. IMHO this was a bit excessive. I think the article was written by people that were in the brass selling business.

 

[Mikeinkaty]

After I started using the Lee Factory Crimp die I have not had a bad crimp. I don't know if it is possible to get a bad crimp with it.

 

[MichiganScott]

With some die sets it is possible to apply a crimp that is heavy enough to actually spring back from the bullet you just damaged and allow you to turn the bullet by hand.

 

[johngalt]

I go light on the crimp - similar to factory cartridge. If my bullets aren't moving under recoil, then there us enough.

Neck tension is important, too much crimp can loosen it.

 

[patrickd]

You can over do anything and everything.

 

[forestswin]

Quantifying a crimp

crimps are generally described as light, medium and heavy
and that's a little frustrating, especially to a new reloader

I like Mike Venturino's description of a roll crimp
in Lyman's Cast Bullet Handbook (4th edition) page 61

"....run his fingernail down the bullet and over the case mouth. If it does not hang up on the case mouth there is enough crimp"

In my revolvers and 357 lever gun, I only shoot lead SWC's, truncated cones and WC's that have crimp grooves. to set-up the die, I incrementally increase the crimp until it passes the finger nail test and then stop - beyond that I consider the crimp too much!


for taper crimps, I measure the finished round case mouth diameter for repeatable, uniform crimps

the case of a sized 45 ACP measures 0.473" at the mouth

with my 0.452" bullets and my IMI cases - I set the taper crimp to give a 0.470" diameter - this puts the case snug to the bullet without deforming the bullet

YMMV based on your case wall thickness, bullet diameter, etc.

 

[Jupiter01]

My problem was that about 20% of my reloads would not chamber in my revolver. I thought perhaps a bulged case. I ran them through my Lee FCD, which reduced the percentage, but did not totally solve the problem. Probably user error.

I then had a conversation with an RCBS tech, who was rather snotty...unusual for an RCBS tech, from past experience, but he said that factory crimps are an "overcrimp", and that with RCBS dies, 1/8-1/4 turn beyond contact with the case mouth was all the crimp I needed. Be that as it may, I also use the "fingernail test", as the last poster said.
Since adjusting my seat-crimp die, I've had no need to resort to the FCD.

OTOH, I have started using my Dillon crimp die more since I found out that they both taper and roll crimp. With plated, no cannelure bullets, I crimp just so the flare on the case is eliminated, and moved against the bullet, so there is no "lip" to cause a hang-up. I lightly chamfer the interior of the case mouth, and have seen no damage to the plating when I have pulled the bullets.

The last frustrating problem I have to overcome is...How to eliminate the bulge that the bullets put in the reloaded cases. It doesn't hurt anything, but looks tacky!

 

[gwpercle]

Yes . Too much crimp will usually cause the case to bulge below the crimp, the bulge can interfere with cambering the round.
Backing off the crimp die will apply less crimp and eliminate the bulge .
Gary