Fine tuning loads lee factory crimp die

[JDD]

The problem with crimping is that it can be very dependent on case OAL as well as ID and OD chamfer angle and depth. All these variations can affect the severity of the crimp.

On top of this, crimps will typically deform the bearing surface of the projectile. This bothers long range shooters because it can be very difficult to quantify.

To avoid this a lot of long range shooters simply avoid crimping and tune with the other more quantifiable means like seating depth or neck tension.

Ammo can be accurate with or without a crimp. Most longe range guys just avoid it for the sake of simplicity or because they have been advised to do so.

A collet crimp is applied from equally from a 90 degree angle. Is not subject to case length differences. collets are used for precision holding endeavors in machining, And many other engineering endeavors

 

[Petey308]

Here's another excerpt from my notes where I've discussed this before with someone:

I can tell you why you're getting better consistency. You're getting more consistent neck tension. The collet on the FCD is applying a consistent amount of neck tension on the mouth of the case.

Nathan Foster has a section in his reloading book talking about it.

I've experienced the same thing, and after reading his book, it all makes sense now.

Consistent velocity is derived from consistent neck tension and consistent pressure, as well as proper bullet to bore concentricity/alignment.

I myself have gone the route of annealing and using a mandrel. I have also experimented in the past with the proper size bushing die, but to achieve true uniform neck tension throughout the length of the neck with a bushing due, you really need to turn the necks to ensure the thickness is even and you're not applying more tension on one spot on the bullet that is more than another. I get great velocity consistency annealing and using a mandrel to see final tension, and I don't have to worry about crimping.

Crimping can actually reduce velocities. More energy is used to release the bullet and thus velocity is reduced. That's a big reason why I don't like to do it. I've never had an issue with bullets moving from recoil.

If you don't anneal, using a FCD is a great way to essentially cheat at getting consistent neck tension. It's essentially a crutch.

Too much crimp can give negative results though. That's why if you're doing a crimp, it's best to experiment and find the best amount of crimp that works best. It's also imperative that all your cases are trimmed consistently to the same length as different lengths will result in different amounts of crimp.

 

[ericbc7]

For those wanting some data on impact of crimping pressure on accuracy :
https://ar15armory.com/forums/topic/100120-consistent-crimp-test-finalized-pic-heavy-and-long/

I realize some won't consider this small experiment to be enough evidence to change opinions and it is too small a sample to make confident generalizations. But the test does give a fairly good demonstration of how changing one variable can apparently affect a complex process like group size. It should, at least, encourage some humility in the absolutists on the subject.
Reminds me of the quote by Bacon(?) "You cannot by reason change the ill opinion of a man, which by reason was not obtained".

 

[misterc01]

I do not crimp my rifle ammo.

 

[Canadian Bushman]

A collet crimp is applied from equally from a 90 degree angle. Is not subject to case length differences. collets are used for precision holding endeavors in machining, And many other engineering endeavors

The length of the case determines how much of the neck is crimped. If you have large oal variations you will have large crimp variations. Neck thickness variations will also cause different amounts of crimp. If you control these aspects you will only see the changes caused by the crimp. If you do not you will add variations to your reloads.

Ive been a machinist for 15 years. Im some what familiar with collets and their uses.

 

[INVICTUS]

maybe you could provide PROOF. i shoot long range br.

I shoot for a living . Nothing on a forum constitutes proof. The point is not to stifle questions that generate the sharing of information. So if you can't provide some decent input maybe you should get out to more bench rest events so you can gain the proof you need in order to produce some pertinent input in the future instead of acting like the most profound and final word.
We all weren't aware that you were the final knowledge on all things shooting. We sort of thought maybe there were somethings you hadn't discovered yet but I sure stand corrected . For myself , I'd like to hear what people say on the topic since it's a good discussion. Just my two cents .

 

[therifleman556]

That's most of his posts. He specializes in condescension toward any thoughts not in line with his.

 

[Petey308]

So, just to add a summary to my posts, I do not put any sort of crimp on any of my rifle loads. I've done plenty of testing and experimenting of my own to come to my conclusion. I actually used to use those crimp dies and believed they were awesome. It's not hard to do your own tests and come to your own conclusions.

In my experience, neck tension is key for accuracy and low SD/ES. Yes, you can achieve it by using a FCD, but it's an inferior method. Why go an inferior route when accuracy is detrimental? This is long range hunting, so with that in mind, the clean kill of an animal is front and foremost. Stacking the odds in your favor for that should be priority. Like I said, a FCD leaves the round open for compromise. Why would you want the highest and greatest amount of tension on the bullet only around the rim of the case neck?

If you truly want the best, starting with an annealed neck that has been sized with a mandrel is the best way. Now you have even and adequate tension throughout the entire length of the neck contacting the bullet, not just at the mouth of the case. Increase your tension to .003" and you'll see a decrease in your SD/ES. Do that by decreasing the diameter of your mandrel.

The big plus to a mandrel is that if there are inconsistencies with the thickness of the brass at the neck, it will push those inconsistencies to the outside diameter, leaving a flush and uniform surface on the inside diameter to contact the bullet. A bushing die will push those inconsistencies to the inside diameter and create uneven contact with the bullet. That is, unless you turn the necks to achieve consistent thickness.

Using a FL sizing die with an expander ball will create tendencies where the expander ball stretches the neck and shoulder of the case as it exits the case. A mandrel does not do this.

I can elaborate on this process if you'd like, but I'll keep it brief and simple for now.

 

[INVICTUS]

Collet crimping (FCD) and increased neck tension TYPICALLY reduces velocity due to more energy being spent releasing the bullet from the case. A collet crimp, or increased neck tension, will also reduce ES because it makes a more consistent contact with the bullet, resulting in a more consistent release.


I use a Lee FL die for several cartridges. I remove the expander ball from it, using it FL size the outside dimensions of the case. Then, I use a mandrel in a separate step to set final neck/bullet tension. My tension is right at .003" and is extremely consistent throughout the length of the neck thanks to the mandrel.


I also turn my necks too, but that's not really necessary when using a mandrel. It's just something I do out of anal retentiveness.


You can get a mandrel setup from somewhere like K&M. You can get one machined to the exact size you want to give you your desired amount of tension. A mandrel and the press adapter are $30 or less.


Use that along with your Lee FL die and a quality seating die, and you can make very consistent and accurate ammo for pretty cheap.


At .003" of tension, you don't need a crimp. I don't crimp any of my bottle neck cases and I run semi-autos as well bolt action. They run very consistent, cycle smooth, and I get no bullet setback. My SDs are under 5fps and my ES is below 10fps.


While increasing uniform neck tension can increase your accuracy and decrease your SD/ES, so can utilizing a FCD. It's not as superior of a method though. Collet crimping puts peak case neck contact with the bullet only on the point of the crimp. If the bullet gets bumped, it's compromised. It may no longer be consistent with your other rounds. Mishandling of the rounds, rough cycling/feeding, etc is all it takes.


By setting your entire neck to a consistent amount of tension, you don't need to crimp and it makes the point if contact with the bullet uniform throughout the length of the neck and bullet's bearing surface. That means it's not easily bumped out of round

Thank you for the detailed information. Your post is the kind that keep me coming back. Great explanation of method and variables.

 

[INVICTUS]

That's most of his posts. He specializes in condescension toward any thoughts not in line with his.

Roger all.

 

[gohring3006]

I've tested the crimp die on several cartridges. I have enough data to show, if someone is using a Lee crimp die and achieving outstanding ballistic data, I am not going to argue with them. I seen it work and not work. I used it on a factory savage creedmoor and it flatlined my Es and SD. I have one in every die set that I currently have. I don't use them on every cartridge, but if I have trouble getting a rifle to settle down, I'll definitely try it.

 

[JDD]

So, just to add a summary to my posts, I do not put any sort of crimp on any of my rifle loads. I've done plenty of testing and experimenting of my own to come to my conclusion. I actually used to use those crimp dies and believed they were awesome. It's not hard to do your own tests and come to your own conclusions.

In my experience, neck tension is key for accuracy and low SD/ES. Yes, you can achieve it by using a FCD, but it's an inferior method. Why go an inferior route when accuracy is detrimental? This is long range hunting, so with that in mind, the clean kill of an animal is front and foremost. Stacking the odds in your favor for that should be priority. Like I said, a FCD leaves the round open for compromise. Why would you want the highest and greatest amount of tension on the bullet only around the rim of the case neck?

If you truly want the best, starting with an annealed neck that has been sized with a mandrel is the best way. Now you have even and adequate tension throughout the entire length of the neck contacting the bullet, not just at the mouth of the case. Increase your tension to .003" and you'll see a decrease in your SD/ES. Do that by decreasing the diameter of your mandrel.

The big plus to a mandrel is that if there are inconsistencies with the thickness of the brass at the neck, it will push those inconsistencies to the outside diameter, leaving a flush and uniform surface on the inside diameter to contact the bullet. A bushing die will push those inconsistencies to the inside diameter and create uneven contact with the bullet. That is, unless you turn the necks to achieve consistent thickness.

Using a FL sizing die with an expander ball will create tendencies where the expander ball stretches the neck and shoulder of the case as it exits the case. A mandrel does not do this.

I can elaborate on this process if you'd like, but I'll keep it brief and simple for now.

There' is logic to what you profess. Neck tension is the key. Brass with uneven neck thickness would not be considered for my needs . I am looking at the collect crimp as a solution to consistent neck tension with out adding bullet run out. I use the Redding competition sizer and seater. . I found that the sizer did more to reduce bullet run out than the seater. Especially when necking 280 down to 6.5. I like to leave a short section of the neck unsized to insure bullet alignment to the bore and just barely kiss the lands. I can only do that with bushing dies. If your chamber is dead true this is I believe is the best way. The only neck size collet dies I am aware of are lee. Any body else produce them. Does t the bullet push any uneven neck thickness to the outside just like a mandrel? Are you measuring run out

 

[coop2564]

So, just to add a summary to my posts, I do not put any sort of crimp on any of my rifle loads. I've done plenty of testing and experimenting of my own to come to my conclusion. I actually used to use those crimp dies and believed they were awesome. It's not hard to do your own tests and come to your own conclusions.

In my experience, neck tension is key for accuracy and low SD/ES. Yes, you can achieve it by using a FCD, but it's an inferior method. Why go an inferior route when accuracy is detrimental? This is long range hunting, so with that in mind, the clean kill of an animal is front and foremost. Stacking the odds in your favor for that should be priority. Like I said, a FCD leaves the round open for compromise. Why would you want the highest and greatest amount of tension on the bullet only around the rim of the case neck?

If you truly want the best, starting with an annealed neck that has been sized with a mandrel is the best way. Now you have even and adequate tension throughout the entire length of the neck contacting the bullet, not just at the mouth of the case. Increase your tension to .003" and you'll see a decrease in your SD/ES. Do that by decreasing the diameter of your mandrel.

The big plus to a mandrel is that if there are inconsistencies with the thickness of the brass at the neck, it will push those inconsistencies to the outside diameter, leaving a flush and uniform surface on the inside diameter to contact the bullet. A bushing die will push those inconsistencies to the inside diameter and create uneven contact with the bullet. That is, unless you turn the necks to achieve consistent thickness.

Using a FL sizing die with an expander ball will create tendencies where the expander ball stretches the neck and shoulder of the case as it exits the case. A mandrel does not do this.

I can elaborate on this process if you'd like, but I'll keep it brief and simple for now.

I agree with this said, however the avg reloader will not or is not capable of going to these lengths to achieve good repeatable neck tension, therefor for the avg guy a FCD in light crimp is the best way to reduce ES, flyers for med/Long range shooting IMO. Hunters should not jam or touch lands to produce these same results due to field issues with that type loading. Many have said test, I have and for me I get much better ES over a wider range of reloads per case using a FCD with the larger caliber rds. Many reloaders will just call I pulled that flier, when really it was not pulled just one of many neck tension issues that a FCD might of helped with. For a reloader that is only going to reload a case 4 times probably doesn't need one, but if your going to try much more than that I found it helped a lot in Keeping my ES consistent, since I do not go to all the lengths mentioned. Anything more than a Light crimp in my testing hurt accuracy in my large rifles.

 

[gohring3006]

I agree with the crimp die helping with consistency in neck tension, I also seen data where a primer might start a bullet in motion before the powder is ignited. The crimp die can hold it just long enough to get the powder ignited. Imagine if one cartridge allows the primer to start the motion and the very next cartridge doesn't. The crimp die will make this consistent.