Crimping and loading for accuracy

[marine6680]

For 223:

Recently got some higher quality bullets Nosler to load up, and was wondering about crimping.

I have a Lee factory crimp die... I set the die up per instructions, but backed it off a bit. The instructions say that when the 4 pieces of the collet touch, that is max crimp. I do not have it set to max crimp, I believe that the instructions say to go half a turn past the die touching the shell holder. I have it set to a quarter turn, so half crimp.

I noticed that even that crimp is pretty strong, I tried pulling one of my prior loads, and ended up giving up. (kinetic bullet puller)

I am guessing how much crimp I need is just another variable and dependent on the components and rifle... but is there a too much crimp?

Any tips on how to work up loads with crimp as a variable? Or maybe advice on setting up for a good general crimp...

Also, when developing loads for accuracy, would it be best to work in .1gr amounts or what?

Thanks

[NWPilgrim]

You'll get a lot of varying responses. Personally I rarely crimp and never if there is no cannelure. I've found in bottleneck cartridges the neck tension itself is plenty secure for use in AR15, M1 Garands, and a PTR91.

So you might start with no crimp and see if you ever have an issue or need to do anything different. I have no feeding failures, no loose bullets, and sub-MOA accuracy with no crimp. I see no reason to add a crimp. YMMV of course.

If you add a crimp then you should understand why you are putting it there in order to know how much to apply. I believe the military specifies a cannelure and crimp on its ammo because it can be run through a machine gun that has much more violent feeding, and any hiccup will jam it up. So it may improve reliability over millions of rounds through hundreds of thousands of select fire weapons. For bolt action or semi-auto shooting I have not seen where crimping is needed.

[steve4102]

This subject comes up a lot, I mean a lot. IMO, there are basically three types of AR handloaders, those that crimp, those have crimped and those that have never crimped.

As this thread progresses you will find that the biggest naysayers as far as crimping goes are those that have never crimped. They will tell you how evil crimping is and how you should not do it cuz the Benchrester's don't do it, how it will degrade accuracy, etc, yet they have never tried it and have no experience with it. Go figure.

but is there a too much crimp?

IMO yes, you can over crimp. If your crimp smashes the hell out of the bullet, you have destroyed the integrity of the bullet and accuracy will suffer.

I use what I call a "Medium Light" crimp. With the round in the die and the ram all the way up the collet fingers have plenty of space between them and do not touch. It may take a little practice and range time setting it up just right.

Here is a little test I did with my 223/5.56. This was with 55gr HP no-cannelure.



When working up loads in my AR's I go with .5gr increments.
This target was at 100 yards.
Colt AR-15.
55gr Midsouth HP bullet no cannelure.
Med Light Crimp.
10 rounds at each target.

[oldpapps]

Accuracy is a mix of many, many things, but all of them include consistency.

For a consistent crimp the brass must be the same length, case neck the same thickness and hardness (or softness). This is assuming that each of the bullets is the same diameter and seated to the same location.

Add to the mix the case volume must be consistent (I don't care how heavy or light the brass is but this is a good indication of case volume).

Now we will move on to the propellant, oh my!
Some powders like higher start-up pressures, crimped.

I conducted an experiment looking at the effects of 'Magnum' primers in comparison with 'Standard' primers. (This was not a valid scientific process, only looking for indications and tendencies.) What I observed was mag primers gave a little greater velocities (what a surprise), I couldn't detect in my very limited test run any measurable deviations between the two primer types. (This was only judging primers from two lots from the same maker.) I also included (more to the point of this thread) 'No' crimp, my 'Medium' crimp and 'Heavy' crimp. Velocities were lower with 'Heavy' crimp. (I think the heavy crimp actually lessened the neck tension and reduced the overall bullet pull.) Next was 'No' crimp. And the best velocities were with my 'Medium' crimp. (As the degree of crimp is very subjective and as I see it, not measurable by my means. 'My' medium is just that, 'my' guestamation of medium.)

The point is; consistency in all controllable factors and test each variable for best results. And 'crimping' is only one variable.

Good luck and enjoy,

OSOK

[Mike38]

I’ve done some testing on Lee Factory crimp die vs. no crimp on .223. I crimp what would be considered light per Lee’s instructions. My unscientific results found that the crimped rounds gave me around 10% better accuracy. YMMV.

[HJ857]

This certainly can be a volatile topic of discussion! We'll see how this thread goes...

I feel that the FCD is something you must test to determine if it's worth using. It's just one more step in the process of working up a load.

In my experience it makes no difference for my .223 loads. Because it doesn't matter, I go ahead and apply a light crimp.

My .308 loads on the other hand, do show better consistency and accuracy with a very light touch with a FCD, using matched brass and all other factors being equal.

[Bart B.]

There has to be some reason why folks shooting bullets attaining the best accuracy don't crimp their case mouths onto bullets. By "best accuracy," I'm referring to those who get no worse than 1/4 MOA at 100 yards, win matches and set records in competitive shooting disciplines. Sierra Bullets makes special 22 caliber 77 grain cannelured match bullets for folks who want to crimp them in cases. But they test them in uncrimped cases because they get better accuracy without the crimp.

Crimping case mouths onto bullets is sometimes done by others. If one gets best results with their stuff using crimped cases on bullets, by all means do so.

[Dave P]

So you got some better bullets now. Why would you want to modify the bullet shape by crimping it?

I am sure Nosler spent a lot of time and money developing and testing the profile of that bullet. Do you think you can improve the performance by re-shaping that bullet??

(but yes, there are multiple factors in play when you crimp. It may improve the accuracy of your system. Run some tests.)

[steve4102]

Originally Posted by Dave P

I am sure Nosler spent a lot of time and money developing and testing the profile of that bullet. Do you think you can improve the performance by re-shaping that bullet??

If you are "reshaping" the bullet with the Lee Factory Crimp die you are over doing it.

OH BTW, just so you know, as soon as that bullet is slammed into the rifling at warp speed it is deformed

[Bart B.]

OH BTW, just so you know, as soon as that bullet is slammed into the rifling at warp speed it is deformed.

While bullets are pushed into the rifling quite a bit less than warp speed (typically a couple hundred fps), they are certainly deformed. To be more precise, they are swaged down in diameter (in barrels shooting them most accurate) as well as engraved by the lands. But it's extremely uniform all the way around. How else would they shoot well into the ones when tested for accuracy or shot in competition without crimping from the case mouths they left from?

When made, an HPBT bullet's jacket is deformed around its lead core into a boattail on its back end and pointy hollow point on its front end in the last machine. To say nothing of the 80 pound bar of lead that's deformed into bullet cores and a sheet of jacket material that's deformed by coin, cup, draw and trim operations. All these deforming operations happen at 80 to 100 times per minute. But they're very uniform in making the end product.

Deforming stuff consistantly is our friend. Crimping's been proved to deform bullets; microscopically and often not easily seen, but proper accuracy tests have proved it for decades. Arsenals quit crimping 30 caliber cases on bullets years ago when they found out even cutting a crimping groove in FMJBT bullets made them shoot less accurate.

[steve4102]

Like I said in my first post. Those that have never crimped will come along and tell you how wrong you are for crimping. Life is funny that way, those with the least experience have the most to say.

[Bart B.]

Then there's those who've learned from others who've tested crimped and non-crimped ammo to a much greater degree than anyone posting on this forum. And choose not to crimp because it degrades accuracy.

When those that crimp produce ammo that shoots as good as those who don't, I'll look into it. Show me some consistant sub 1/4 MOA groups with crimped ammo and I'll be interested.

[marine6680]

Like I said in my first post. Those that have never crimped will come along and tell you how wrong you are for crimping. Life is funny that way, those with the least experience have the most to say.

I have read a few studies on such a phenomenon...

I will see what works for me, crimp or no.

Then there's those who've learned from others who've tested crimped and non-crimped ammo to a much greater degree than anyone posting on this forum. And choose not to crimp because it degrades accuracy.

When those that crimp produce ammo that shoots as good as those who don't, I'll look into it. Show me some consistant sub 1/4 MOA groups with crimped ammo and I'll be interested.

(this is not a dismissal of your comments or ideas)

As with anything in life... bias can creep in... Even personal testing can in the end be worthless, as it can just be fueled by confirmation bias. And anything that gains a stigmata (as it were) can fuel bias in testing. (humans avoid taboo, and going against the crowd, crimping may hold this distinction in the competition realm)

I am not saying they are wrong, just that I can't take their results strictly at face value, nor can it be simply dismissed off hand. The results are worth looking at due to the results they produce at the range... But the results can not be taken as the last word, as not believing in crimping can lead to less than objective testing and that isn't hard to do in such a comparison. Its insidious and most people do not realize it is happening. It can even happen subconsciously... causing less than top performance when testing a load that goes against bias...

The only true objective test would have to come from blind testing using a rigid test barrel, with as many possible combinations of powder and crimp and seating and trim length and primer and brass and bullet... and then even barrels vary, throwing another in a long list of variables... that much variability would be exhausting, maybe even prohibitive.

Individuals will usually stick with the first thing that worked well for them, then use that as a start point for any further development down the line. Its called the anchoring effect. So,even long time frames of testing by a person can be limited.

Crimping may hurt, help, or do nothing...

In the end, I can only go by the results of my own testing. I don't care one way or the other which is better, nor do I care what others do... even the top pros. Its all about my results. The answer to the question of which is ultimately better, is not important to me. I came here looking for ideas on how to start with developing for testing, and everyones replies have been helpful.



I will start with various weights of powder in the low to medium range (as those seem to be more accurate in lab testing) and various amounts of crimp from none to medium. I will play with further variables as I gain experience with loading... I may find that a load that works well with a crimp may not when another variable is changed... and then I may find a crimp helps once again as another variable is changed. Its a process, and I will use what I find best for me in my testing... crimped or no.

Once again, everyones responses have been helpful in helping me find direction, or at least solidify my thoughts.

[Slamfire]

It is a sad fact that so many are susceptible to Corporate Advertizing. There is real validity to the idea that our culture is a creation of advertizing bureaus, and the idea that crimping improves accuracy is, of course, a creation of corporate advertizing.








Of course deforming the bullet makes it less accurate. This is something that should be obvious: no one can improve the concentricity, center of gravity, with a crimp die.


The book “Ultimate in Rifle Accuracy” by Glenn Newick , has one short chapter on the bullet. It is an interesting read on the history of accurate bullets. Accuracy improvement has been directly related to improvements of uniform jacket thicknesses and uniform leadcore distribution. He mentions that a bullet making die manufacturer making a core seater with has less than 25 millionths of an inch runnout. Today’s match bullets are the best ever in the history of shooting sports and there is nothing the hobbyist reloader with a press can do to improve them. Crimping will deform the jacket, will deform the soft lead core, shifting the mass of the core in an irregular manner, shifting the center of gravity of the bullet. Once the center of gravity is outside the axis of rotation the bullet’s flight path will be erratic.


Bullet manufacturer's agree:



Follow the Lee Factory Crimp die instructions to the letter, and your match bullet will look like this:





Lighter crimps will leave indentations on the bullet jacket, rest assured that the damage to the core is greater as the springback of copper and lead are different. Lead does not springback very well at all.

Like I said in my first post. Those that have never crimped will come along and tell you how wrong you are for crimping. Life is funny that way, those with the least experience have the most to say.

Having neither the energy or ability to prove that crimping improves accuracy, Steve4102 is looking for a champion. Well, so am I. I have heard of a theory called the “Rubber Ball”. According to this theory, which has been stated by some authorities, accuracy will be improved if the shooter stops letting silly thoughts, day dreams, worries, etc, from intruding as he shoots. The way to banish this mental discord is by displacing these demons of distraction from the physical being. The procedure , as described, is during the record string, the scorer will strike the shooter on the head with the flat of a wooden oar. When properly struck, the shooter’s head will bounce like a rubber ball upon his shooting mat. Once correctly dazed, the shooter’s nervous system will be in a calm state and in this condition the shooter will be capable of pulling the trigger without any intrusion of unwanted thoughts. Or of having any thoughts at all.

I however, I do not have the time, energy, or skill to actually conclusively prove this theory and like Steve, I am looking for a champion.

Any takers?

[steve4102]

Hey Marine, take a look at this little test.
Not very scientific, but a real live test just the same.

No, he said she said, no theory or supposition, just some guys with guns testing the Lee Factory Crimp die. Note in all three rifles accuracy was improved. If you read the comments by the author, it appears even he was surprised at the results.

http://www.accuratereloading.com/crimping.html

OH and when you get to crimping, don't smash the hell out of your bullets like Slamfire does. That's just blatant misuse of a tool, them blame the tool. It's akin to cutting a board to short then blaming the saw, or bending a nail and blaming the hammer.

Carry on. I will be eagerly awaiting your test results.

[marine6680]

That is some heavy crimp...

I don't even crimp my plinking/blasting rounds that much.

[marine6680]

The difference that test shows is not huge... It does show a slight advantage. It is just too small of a test I think.


Another thing to think about...

Return to mean. (return to average)

Basically, humans, even those with high level of skill are still subject to random chance... luck.

You will always have outliers of good and bad that can skew results. So you need large sample sizes to average out their effects. (high skill does limit these outliers)

In a small sample, these random chances of particularly good or bad single results can line up to show advantage where none exists... or give results opposing to truth.


As far as amount of crimp... on a non-chanalature bullet, I am thinking that just putting enough "crimp" to ensure that the neck is holding well and tight against the bullet, but not enough to deform the metal, is the most that should be applied. To ensure good/full neck tension as it were.

[HJ857]

I've always hoped I could acquire tools to quantify runout but have never gotten around to it.

I've always considered that the real benefit of the FCD is that it improves concentricity more than any other factor, possibly neck tension as well. But again, that is just conjecture.

I would also note that IF you're loading for a multi thousand dollar rifle capable of .25 moa, then Bart's posts are relevant. On the other hand if you loading to squeeze the best out of a typical one or two moa rifle that costs less than a grand, then those posts are less meaningful. It's kind of like saying "I don't know any top fuel dragster that runs on 87 octane from Speedway, but if you can show me one, then I'll believe you're onto something"

[NWPilgrim]

We need to wrap this up soon, gents, before the next crimping thread starts! Fun anyway.

Whether you crimp on not it affects no one but yourself so do what you prefer. You can start with "It works fine without it so why add one?" Or, "it may help so why not do it?"

Some of us have done it both ways and I would not lose sleep over either one. My preference is generally not to crimp but on 62 or 55 gr FMJ with cannelure I crimp anyway but have noticed no real change either way. I have tried very light crimp on 69 gr SMK but you have to crimp super light not to dent the jacket and then I ask if I crimp so light what is the point? Trying it without a crimp I found neck tension is plenty tight and never found it to be a problem. I easily get 1/2"-7/8" groups out of a service grade barrel without much case prep either so that is plenty good enough for me.

I did find that some commercially pulled bullets must have been overly damaged in the jacket or core by the puller because they are far less accurate than bulk M855 ammo.

[totalloser]

I think it really depends on what you are shooting the .223 in. If it's a bolt gun, and you are shooting sub 1/4" moa, well don't breath on it or it will affect accuracy. And a crimp is likely to be detrimental to accuracy.

However, if you are shooting in an auto, it may or may not help. As you lean towards looser controls (mixed headstamps etc.), the crimp starts to help accuracy. I experienced some improvement with the crimp, but it was minimal. I chose to crimp for reliability primarily.

The vast bulk of .223 consumed is in autoloaders which like others have stated are most likely shooting in the 1.5" to 3" range. In my favorite mini, I picked up .5" reduction (2.5" to 2") in grouping after adding FCD at station 5, but can't say it was all due to the crimp since my high volume reloading is not tuned to bench rest but rather blasting.

[Bart B.]

None of the high-quality most accurate commercial or military match ammo used in semiauto service rifles has crimped mouths on their bullets.

[Scimmia]

Amazing, Slamfire has been posting evidence of his incompetence for years and continues to do so even after it's been pointed out many, many times that he grossly overcrimped those bullets.

[steve4102]

Amazing, Slamfire has been posting evidence of his incompetence for years and continues to do so even after it's been pointed out many, many times that he grossly overcrimped those bullets.

Is it "amazing" or is it just "sad"?

[4runnerman]

I did the test with my 223 and 308. Very un professional I am sure. In both cases not crimping worked better for me. I am sure in certain settings maybe a slight crimp is better but just did not work for me. I think in those pictures we see here the case is that, while crimped seemed to shoot more accurate than not crimped,the story was the pressure difference behind the test. I think If the un crimped load was loaded a little hotter or a little cooler the results would have been different.

2 loads, loaded exactly the same,one crimped,one not crimped is not a valid test. Pressure differences are going to be there. To those that crimp- Do your own test. Get your best crimped load,and now work up a load un crimped from scratch. I think what you will find is what all of us have already- Un crimped loads will shoot more consistant and more accurate.

[Bart B.]

What some folks may not realize is Slamfires bullets were shown to show that crimping changes the bullet body shape. In reality, the bullet jacket is only pressed in .0001" or thereabouts with a light crimp but a lot more with heavier crimps. This can be seen by laying a pulled crimped in bullet on a precision gauge block with its measuring surface smooth to .000005" or less. Put a micropoint light source next to the bullet near the gauge surface then look at the bottom of the bullet from the other side. Any jacket impression left by the crimping process will be enough to let light shine through between the gauge block and bullet jacket. Such deforming cannot be seen with normal pictures posted on this forum. Do your own tests like I did and you'll be surprised.

Deforming bullets; well balanced bullets properly handloaded don't deform at all when fired. Even Lapua D46 185-gr. FMJRB match bullets at .3092" diameter shot in a 6-groove Hart barrel with .3087" groove and .2995" bore diameters are not deformed per se, but insted evenly swaged down by the bore and leave the muzzle perfectly balanced. They were just smaller in diameter and had spiraled "flutes" in them made by the rifling lands.

Proof of this happened in 1971 when a friend took a few hundered of those Lapua match bullets, put them in a collet held by a Dremel MotoTool, spun them at 30,000 rpm with an ampmeter in the power cord. Perfectly balanced bullets drew a given amount of current. The more unbalanced a bullet was, more current was needed to spin the collet up to speed evidenced by more milliamps read on the meter. Some of the very unbalanced ones flew out of the collet and bounced off the walls and ceiling of the tool room at Sierra Bullets where they were being tested. But he ended up with several dozen perfectly balanced ones. Those bullets left at about 2600 fps and the 1:11 twist spun them at 170,182 rpm; enough that even microscopic unbalance would be masked by subtle air currents and muzzle velocity spread

Shooting them in his Win. 70 based match rifle clamped in a machine rest, he shot several 10-shot groups at 600 yards. They ranged from about .7" up to about 1.5". A picture of one about .9" was put in a Lapua Bullets ad on a page in a fall 1971 issue of the American Rifleman Magazine. He next put 40 shots into a 1.92" group at 600 yards. All from unprepped WCC58 match brass full length sized.