Crimping without a bulge

The bulge is caused because you are crimping too hard. It pushes the case mouth downward and bulges outward. This also destroys the neck tension which will cause the bullet to move during recoil from the fired round. Back off on the crimp. Also, seat and crimp in separate steps. Many swear by seating and crimping in one step. I dont.

BW460 said:

The bulge is caused because you are crimping too hard. It pushes the case mouth downward and bulges outward. This also destroys the neck tension which will cause the bullet to move during recoil from the fired round. Back off on the crimp. Also, seat and crimp in separate steps. Many swear by seating and crimping in one step. I dont.

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He nailed the basics. Not only are you causing function issues, but your probably also hindering neck tension. I like a roll crimp for 38 but it's not nessary. If you separate the steps you will also get more consistent seating depth.

Your brass is not the same length.
Trim your brass to solve the problem.

BW460 said:

The bulge is caused because you are crimping too hard. It pushes the case mouth downward and bulges outward. This also destroys the neck tension which will cause the bullet to move during recoil from the fired round. Back off on the crimp. Also, seat and crimp in separate steps. Many swear by seating and crimping in one step. I dont.

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joneb said:

Your brass is not the same length.
Trim your brass to solve the problem.

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This here. Well said.

Walkalong said:

but many don't trim

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If the brass is not the same length the crimp will be different, it is what it is.

Other then to much crimp..........

When the bullet is placed into the case crooked & seated, one side of the case body will have a bulge.
This bulge may prevent the rounds from chambering correctly.

The expander must be of the correct diameter. Even better if expander is the "M" type.

The seating plug has to fit the bullet. Best if contact is on the side of the bullet, above the ogive. . Most of my semi-wadcutters make contact on the flat nose.

You can also seat and crimp in two different stages. Will remedy some of the bulge. In heavy recoiling guns like 460 and 500 (and the 329 PD) ive found i have to over crimp to stop bullets from walking out. The only way to put such a heavy crimp is to seat in one stage and then go back and crimp.

crestoncowboy said:

In heavy recoiling guns like 460 and 500 (and the 329 PD) ive found i have to over crimp to stop bullets from walking out.

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Neck tension should be higher to help eliminate bullet movement. The big guns use .004"

Even my 10 oz 38 special +P S&W 337PD, comes with a warning not to use lead bullets, because of possible bullet jump. Lead is all i use. Good neck tension doesnt let the bullets move.

Here soft lead alloys are not your friend. Internet reports sizing of bullet by the brass, not good.

All above is VERY good.

Additionally, if your neck tension is correct AND your bullets have an extreme proportion of the bullet side wall in contact with the case wall then crimp may not be needed at all. I shoot DEWC almost exclusively and find that only the faintest of crimps is needed, and that only to assist in chamber entry.


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243winxb said:

Neck tension should be higher to help eliminate bullet movement. The big guns use .004"

Even my 10 oz 38 special +P S&W 337PD, comes with a warning not to use lead bullets, because of possible bullet jump. Lead is all i use. Good neck tension doesnt let the bullets move.

Here soft lead alloys are not your friend. Internet reports sizing of bullet by the brass, not good.

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I've reloaded tens of thousands of rounds for 44 magnum and never had any issue until the 329pd. I had jump regardless of brass. Ive had snake shot bust the plastic capsule and spill the shot when a normal magnum was fired in the cylinder beside it. A good crimp has been fine for me in 460 and 500 but I go heavier than I used to in 44 or others. My 460 and 500 are both 8 inch barrel heavy guns so maybe that's why I never had issue.

joneb said:

Your brass is not the same length.
Trim your brass to solve the problem.

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My thoughts exactly. I always trim my brass. Makes for more consistent M V as well.

BJung said:

The reasons sound good to me. Yet want to also ask, whenever a reloader mentions the crimp as 0.xxx", does this mean they are measuring the diameter of the case at the crimp? I tend to turn my case down to first crimp enough to remove the flair, then turn my die down 1/4 to 3/8 turn more to ensure a crimp. I just eye the crimp and if it looks good to me, I'll tighten my lock ring down and go from there.

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Yes, but this is for a Taper Crimp not a Roll crimp. With TC we are just removing the flare needed to start seating the bullet. In some cases depending on bullet used a TC is not required. Normally this gives max bullet grip.

Roll crimps are measured in turns once contact is made.

BJung said:

I have always had a few reloads that haven't chambered. The bulge located near the crimp made it difficult or almost impossible to seat. I rarely crimp my .38 loads and use the crimp part of the die to just remove the flare. Can anyone explain what might be happening?

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Different case lengths and/or different thickness of brass.

When starting out, I did the same several times with revolver loads as well as for my .45/70.

Same goes for overcrimping plated bullets. A full crimp that can work with a plain lead WC will cut the plating on a DEWC, and the exposed end of the plating will pop off of the bullet in flight. I had this happen last year with a batch of 50 I was a bit to overzealous with, the loads weren’t very accurate and little pieces of plating were cutting random holes in the target.

A bit of trial and error teaches you the sweet spot between too little and too much crimp. In your case, back it down a bit and you’ll be golden.

Stay safe.

joneb said:

Your brass is not the same length.
Trim your brass to solve the problem.

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This for sure. It happens with mixed 9mm all the time, so I separated the seating and crimping operation and started using the Lee carbide FCD.