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To CRIMP, or not to CRIMP

This is a discussion on To CRIMP, or not to CRIMP within the Reloading forums, part of the Firearm Forum category; I am fairly new to Reloading...about 400+ rounds to this point. I have had no issues BUT I have been reading some of the debate ...


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Old February 26th, 2017, 09:10 AM   #1
 
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To CRIMP, or not to CRIMP

I am fairly new to Reloading...about 400+ rounds to this point. I have had no issues BUT I have been reading some of the debate about the Lee Factory Crimp die. Here is my question along with some details about my gun and load.

I use the Lee FCD according to the instructions. I can see that it makes a crimp. However I see that many of the more experienced users just crimp with their bullet seating die. I have set my dies according to how they say they do it and I think it does seem to crimp somewhat.

I am reloading HOT loads out of the Hornady manual in my .45 Long Colt Blackhawk. I use 250 grain XTP JHP with 24 grains of 4227. I love the performance of this round. Some say the factory crimp die will increase the chamber pressures....perhaps too much? Others suggest if I do NOT use the FCD that I may jar loose some bullet seating with the recoil.

What is the opinion of those in the know?



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Old February 26th, 2017, 10:10 AM   #2
 
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Most of my pistol dies are RCBS with one Lyman thrown in and I seat and crimp at the same time. I did at one time have some pieces of Lee around here, but due to poor quality and C/S it was sent down the road, that was 27 years ago.

I run some hot loads through my 44 mag SB using 4227 and I have never had a setback, (which will definitely increase pressure).


I personally don't see the need to use an FCD when the crimp used on an RCBS, Lyman, Redding, Hornady or Dillon die is as good and probably better than a Lee when properly adjusted.

I've read a lot about the "pressure vs crimp" issue and there are a lot of varying opinions on it.

Hopefully the Iowegan will have some insight into the "pressure vs crimp" issue, because I have no personal experience, just what I've read.

Sorry if I upset all you Lee guys, but first impressions last a lifetime.



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Old February 26th, 2017, 11:41 AM   #3
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Carolus64, First, let's look at the very reason why revolver cartridges have a crimp. Neck tension from the case provides about 90% of the total tension .... the crimp should provide the last 10%. Total neck tension holds the bullet in place when there is recoil from adjacent cartridges. Neck tension also helps hold the bullet in place until the powder gets properly ignited. When no crimp is used, bullets will move forward too easily causing powder to ignite erratically. This is evidenced by excessive unburned powder in the bore and chronographing loads with a wide difference in velocity. This is known as "extreme spread". You will find ..... when the crimp is done properly with any brand of crimp die, velocities will be more uniform and bullets won't pull out when other cartridges in the cylinder are fired. A proper crimp is one of the most important issues for accuracy.

I have experimented with many different crimp dies and found they will all provide an adequate crimp when adjusted properly .... no exceptions. There are two types of Lee crimp dies .... standard and FCDs which also do a full length post resize. It's the full length resize that I dislike. Many people think post sizing is the crimp but that is just not true. FCDs do have an internal crimp that works just like other brands of dies. Some people say their cartridges don't touch the resizing ring and my answer is .... then why have something you don't need. When loading lead bullets, FCDs sizer ring will compress the case and make the lead bullet a thousandth or so smaller in diameter. After post sizing (lead bullet loads only) the case gets stretched and no longer provides enough neck tension on the bullet. So .... you end up with a nice looking cartridge but when you shoot them over a chronograph or from a Ransom Rest, they just don't perform as well as cartridges crimped with standard crimp dies.

Jacketed bullets intended for revolvers have a cannelure that is used to roll the case mouth in (thus a "roll crimp") so it holds onto the bullet better. With lead bullets intended for revolvers, they will have a crimp groove where again the case mouth is rolled in to help secure the bullet in place. So .... revolver bullets should get a "Roll Crimp". Cartridges for semi-auto pistols headspace on the case mouth instead of a rim like revolver cartridges. As such, you can't use a roll crimp or you will shorten the case slightly .... enough to cause excessive head space. So ... pistol cartridges use bullets without a cannelure or crimp groove and are "taper crimped". A taper crimp provides two significant advantages .... like a revolver cartridge, the crimp will add to the overall neck tension and have the same benefits as above. A taper crimp will also help the cartridge feed better because the sharp edge of the case mouth will not stub on the feed ramp or chamber mouth as it goes into the chamber.

So as you can see, both types of cartridges really need a crimp. Some people don't use a crimp because they really don't know why a crimp is needed. A crimp will shorten case life because it work hardens the brass to a point where it will eventually split, which is often the justification most people use when they don't crimp. Then there are people that think if a little crimp is good, a hard crimp is better. You can get by with a hard crimp when soft lead bullets are used but NOT jacketed bullets because they are too hard and won't yield when a case is over crimped. Over crimping will actually expand the case and provide less neck tension. Obviously, this will result in incomplete powder burns, erratic velocities, and bullets that jump from recoil in adjacent chambers.

From the above, I hope you can see why a crimp is needed for handgun cartridges. Also I hope you can see the difference between a Lee FCD and other crimp dies.

Most brands of dies sets have a combination crimp and bullet seater in the same die. Many people use both at the same time but in nearly all cases, it's best to separate the two functions. This is done by first seating all the bullets in your batch. The body of the die is backed out where it doesn't touch the case mouth .... no crimp at all, then the seater stem is adjusted to get the proper bullet seating depth. After all cartridges in your batch have bullets seated, you back off the seater stem several turns then tighten the die body until it provides the proper crimp. The procedure is the same for either a roll or taper crimp. Once the die body is set and locked in, all cartridges are then crimped. This procedure is obviously more work but it provides a much better finished product.

Last is rifle cartridges. Crimps will always distort bullets slightly .... enough to cause downrange accuracy issues. So ..... the need for crimping changes. Non-semi auto rifles (ie bolt, lever, or pump action) don't need a crimp and are typically more accurate without a crimp. Semi auto rifles need a crimp for two reasons .... bullets may get pushed deeper into the case as they feed into the chamber. This can cause pressure issues and will certainly result is less than optimum accuracy. Further, when a semi auto bolt slams shut, it can pull the bullets out of the case until they come in direct contact with the lands in the bore. This will indeed increase chamber pressure .... possibly to a point of being dangerous. Lee makes a FCD for rifles too but it is a "collet" that squeezes the case tight on the bullet .... not a full length post sizer. Generally, rifle FCDs don't affect accuracy like conventional rifle crimp dies so they are acceptable but are no better than a conventional rifle crimp die.

As for you concern about chamber pressure .... with nearly all types of powders, chamber pressure peaks after the bullet has traveled about a half inch. This means the bullet is no longer in the case when pressure peaks so crimp has virtually no affect on chamber pressure. Crimp WILL affect how well the powder initially ignites so with a poorly crimped cartridge, pressure may not peak until the bullets has traveled more than an inch .... well into the barrel where it could cause damage. A typical crimp holds the bullet with 40~50 pounds of pressure. This is virtually nothing when you compare it to chamber pressure rated in tens of thousands of pounds of pressure.
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Old February 26th, 2017, 11:53 AM   #4
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Iowegan, as usual, great info. What do you think about the Redding taper crimp dies? I have some Lee FCD for my 45-70 and 458 and I use the Redding taper crimp dies for 454C and 460S&W. Would you recommend switching to the Reddings for the rifle calibers. On both the 45-70 and 458 I use exclusively lead bullets. Thanks.
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Old February 26th, 2017, 11:59 AM   #5
 
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Thanks Iowegan........Finally I 've read an "article" on this subject that was easy to understand and made sense!


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Old February 26th, 2017, 01:23 PM   #6
 
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Great explanation. Thank you, lowegan.
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Old February 26th, 2017, 01:38 PM   #7
 
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Re: To Crimp or not to Crimp

Thanks Iowegan. That was a thorough answer. So it sounds like I was doing it right all along...even if only by chance.
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Old February 26th, 2017, 01:48 PM   #8
 
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Quote:
Originally Posted by Iowegan View Post
Most brands of dies sets have a combination crimp and bullet seater in the same die. Many people use both at the same time but in nearly all cases, it's best to separate the two functions. This is done by first seating all the bullets in your batch. The body of the die is backed out where it doesn't touch the case mouth .... no crimp at all, then the seater stem is adjusted to get the proper bullet seating depth. After all cartridges in your batch have bullets seated, you back off the seater stem several turns then tighten the die body until it provides the proper crimp. The procedure is the same for either a roll or taper crimp. Once the die body is set and locked in, all cartridges are then crimped. This procedure is obviously more work but it provides a much better finished product.

Truth!! I've followed this advice for years with total success. Attempting to crimp the case into a bullet that the seater is still driving into the case has always seemed counterproductive to me.

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Old February 26th, 2017, 03:10 PM   #9
 
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Following what is also clearly Iowegan's logic and advice, when I started reloading I came to the conclusion that I would want two separate dies to seat and then crimp (or close the bell). Since I do not use lead bullets, the Lee FCD was a no-harm option for me.

But ultimately I chose the Lee FCD because my sense of internet info told me it was more capable of dealing with different case lengths. I've had no reason to be unhappy with the Lee FCDs, but have never used any other die as a "crimper".

So the question: Is that true, or just an old husband's tale?
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Old February 26th, 2017, 04:07 PM   #10
 
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One question I've had for a long time is why we don't see crimp instructions or suggestions based on a measurement. I feel like I've been guessing at this for years. Iowegan's comments on this in this and other posts has been very useful. So, I understand a crimp too light and a crimp too heavy results in various outcomes. However, it would be nice to know if light, medium and heavy crimp can be defined as a measurement. Is this possible? I don't use lead but would like to know if there is an answer that covers both lead and jacketed bullets.
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Old February 26th, 2017, 04:29 PM   #11
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Bonk, Both the 458 Win and the 45-70 are nothing more than a stretched out rimmed straight wall cartridge .... resembling a revolver cartridge more than a rifle cartridge. A roll crimp is normally used with these cartridges .... especially when lead bullets are used.

There's nothing wrong with a taper crimp die for rifle cartridges provided a crimp is needed. I use a Redding taper crimp die when loading 223 Rem for my Ruger AR556. When loading 223 Rems for my Remington Mod 700 bolt gun, I do not use a crimp at all.
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Old February 26th, 2017, 04:52 PM   #12
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Twoboxer, When properly adjusted, Lee FCDs apply the same crimp as other brands and are just as sensitive to case length as other brands. Don't let the post full length resizing fool you .... it is NOT a crimp at all .... it just makes cartridges look pretty by eliminating the "snake that swallowed the gopher" look. Just because a cartridge looks nice, it doesn't mean it will shoot better. You can remove the carbide sizing ring in a Lee FCD and turn it into a standard crimp die.

Rugerfan57, There definitely are measurements for tapered crimps. The measurement is taken at the case mouth and should be about .010" smaller than case diameter and taper up to full diameter just 30 thousandths farther up on the case. Roll crimps are judged more on looks .... where the case mouth is just starting to roll in on a cannelure for jacketed bullets. Hard crimps with lead bullets are way more obvious. Tomorrow I'll take some picture of various cartridges so you can see what proper crimps looks like.
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Old February 26th, 2017, 04:59 PM   #13
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Thanks Iowegan.
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Old February 27th, 2017, 09:26 AM   #14
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I only use one die outside the "norm" for my handguns (roll for revolvers using bullets w/canalure or crimp groove, and taper crimp for my semi-autos) and that is a Redding Profile Crimp Die. It has always given me a good even crimp that's sorta a "hybrid" combo roll and taper.

I am no fan of "post seating/crimping sizing" my ammo. I have no problems with chambering any handload, and if I did I would not cover it up by sizing finished rounds, but find out why and fix it. The Lee FCD is just a crimping die with a carbide sizing ring at the mouth of the die. In my experience my FCD ruined some perfectly sized bullets and decreased accuracy and increased leading.

Not a Lee hater, I just don't like to see new reloaders pointed to the FCD as the "best thing since sliced bread", and not towards proper die adjustment...
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Old February 27th, 2017, 10:43 AM   #15
 
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Iowegian...got a question for you...are there some issues with a Lee crimping function at the same time as seating the bullet in their standard (non FCD) dies? the bullet is still moving into the case when the crimp is being applied..I use the FCD some places and some I don't...only for convenience and never for lead....It seems that the movement of the bullet and case in the die while seating the projectile could have some impact on the crimping function...just curious your thoughts...I have my own.
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