Crimped and Not Crimped.

Muir

Well-Known Member
I took my .222 to the range this evening to try some "highly" recommended IMR 8202XBR powder. As is my practice, I loaded both crimped and uncrimped loads for the first test. (25 of each) Normally, I don't worry about the actual speeds I'm getting until I get some notable results, but today I had the chronograoh set up for my .308 loads so I clipped off ten shots of each .222 load: crimped and uncrimped. These are the strips from my Chrony. For those not used to reading Chrony, the arrow points to "Standard Deviation". The number above it is the Extreme Spread. Neither is good but the difference is noteworthy. The accuracy and speeds didn't live up to the 'recommendation' so I won't continue with this powder but the chrono data is telling.

The bullet was a Hornady 52 grain HP Match. The primers were Rem 7.5 BR. All brass trimmed to same length, etc. Other than the crimp, all rounds were as close to identical as I could make them.~Muir


CrimpedChronoDataRED_zps15a4d408.jpg


Sorry this came out so small.....
 
I took my .222 to the range this evening to try some "highly" recommended IMR 8202XBR powder. As is my practice, I loaded both crimped and uncrimped loads for the first test. (25 of each) Normally, I don't worry about the actual speeds I'm getting until I get some notable results, but today I had the chronograoh set up for my .308 loads so I clipped off ten shots of each .222 load: crimped and uncrimped. These are the strips from my Chrony. For those not used to reading Chrony, the arrow points to "Standard Deviation". The number above it is the Extreme Spread. Neither is good but the difference is noteworthy. The accuracy and speeds didn't live up to the 'recommendation' so I won't continue with this powder but the chrono data is telling.

The bullet was a Hornady 52 grain HP Match. The primers were Rem 7.5 BR. All brass trimmed to same length, etc. Other than the crimp, all rounds were as close to identical as I could make them.~Muir


CrimpedChronoDataRED_zps15a4d408.jpg


Sorry this came out so small.....

Hi Muir,
Just looking at your results there, I notice that there's an average of 150 fps greater velocity with the crimped rounds, I'm thinking that all of the crimped and uncrimped rounds are of identical loadings. If so I asume that you will always see an increase in velocity with crimped rounds as opposed to uncrimped, do you think that the lower ES and SD figures are a result of the crimping or the increase in velocity. I'd be interested in your opinions.
Kind regards
​dcg
 
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man size

CrimpedChronoDataRED_zpsd57e25a7.jpg


interesting.
​I have some crimped versions of a load I already use that I have not tried yet
 
Muir, I'm going to give crimping a go out of curiosity as I've not been reloading long (though have had excellent results thanks to help from friends met on here), and a mutual friend of ours swears by it... however another friend of mine who's taught me an awful lot asked a valid question - why is crimping any better than just having uncrimped rounds with consistent neck tension?

Also, how lightly/heavily do you crimp? My lee .308 crimping die gives a barely noticeable crimp, and I've seen others with a visible dent in the bullet from crimping?
 
Hi again Muir
Thinking on a bit further, the last ammunition that I performed a crimp on, was back in my pistol shooting days, I'm not familiar with the lee die which I have read that you use in previous threads, does this impart a taper crimp or a roll crimp.
dcg
 
Muir, I'm going to give crimping a go out of curiosity as I've not been reloading long (though have had excellent results thanks to help from friends met on here), and a mutual friend of ours swears by it... however another friend of mine who's taught me an awful lot asked a valid question - why is crimping any better than just having uncrimped rounds with consistent neck tension?

Also, how lightly/heavily do you crimp? My lee .308 crimping die gives a barely noticeable crimp, and I've seen others with a visible dent in the bullet from crimping?

DCG: I attribute both to the crimping. Notice that if you toss the odd first round of the crimped loads (and i don't dismiss data) the Extreme spread would be around 30 fps, not 60. The brass was Remington, same lot, all trimmed to the same length and loaded in one session.

BD: I would say that maybe it isn't any better than consistent neck tension but that isn't the only factor, and just because you have applied what you think is consistent neck tension, how do you know you truly do have it unless you've tested for pull weight? Brass varies in ductility. There are minute changes in case capacity. Minute changes in ignition and bullet diameter. Crimping levels these variables and is most appreciated in hunting rifles with standard chambers. I shot BR and never crimped; my dies were hand made for my gun, the brass hand sorted and weighed and tested for capacity.... Thinking back though, I doubt if a crimp would have hurt much.

As to crimp pressure. I experiment. I am of the mind that a heavy crimp is OK. With my 308, the press handle makes a heavy thump as I reach the top. Try screwing the die down more. With the exception of light skinned varmint bullets, it does little to the bullet.

I always use this as my argument for crimping: the best factory ammo is usually crimped. The best factory match ammo is crimped. I recently dug out a box of Lake City 30-06 MATCH and hey! it was crimped. It will deliver MOA from a good service rifle 98% of the time. Can't be too bad a practice.~Muir
 
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Neither. It displaces the case mouth inward ala factory ammo. Quite different from handgun ammo or the roll crimp supplied on some rifle dies.~Muir
 
So once you have decided that a crimp is thew way to go, the next question is how.......
I have a standard Lee seating die, and a Lee factory crimp die, bullets have a cannelure, which do I use ?

Neil. :)
 
So once you have decided that a crimp is thew way to go, the next question is how.......
I have a standard Lee seating die, and a Lee factory crimp die, bullets have a cannelure, which do I use ?

Neil. :)
use the seating die as usual then the crime die. set the crimp die up as per instructions then the more you turn the die in the heavier crimp you will get. doesn't matter if the bullet has a canellure or not
 
only adds consistency if all the cases are exactly the same length

Correct for a standard seat/crimp die, where the crimp ring forces the case mouth into a taper or roll crimp.

But the Lee factory crimp die (rifle type) works completely differently using a collet to squeeze the crimp into the neck from the sides, so is less sensitive to trim length. Also no danger of crushing the shoulder if over-crimped, because the case doesn't take any force along its length.

PS: the Lee factory crimp die for pistol calibres is something completely different again.
 
Correct for a standard seat/crimp die, where the crimp ring forces the case mouth into a taper or roll crimp.

But the Lee factory crimp die (rifle type) works completely differently using a collet to squeeze the crimp into the neck from the sides, so is less sensitive to trim length. Also no danger of crushing the shoulder if over-crimped, because the case doesn't take any force along its length.

PS: the Lee factory crimp die for pistol calibres is something completely different again.

but if you have different case lengths and you run them through the collet dies you will see a different width strip on the neck being crimped so I am assuming a wider strip (longer cases) being crimped would lead to more tension than a much narrower strip (shorter cases)
 
doesn't matter if the bullet has a canellure or not

That is why I asked, I crimp all my loads, but these will be the first bullets with a cannelure I have used.
With no cannelure the crimp die is the only way to go, but with a cannelure is the seating die a better bet than the factory crimp die ?

Neil. :)
 
but if you have different case lengths and you run them through the collet dies you will see a different width strip on the neck being crimped so I am assuming a wider strip (longer cases) being crimped would lead to more tension than a much narrower strip (shorter cases)

I don't think the width of the strip is particularly important, the grip comes from the neck either being squished into the cannelure, or forming its own groove into the bullet if there is no cannelure.

I.e. I think it is the corner formed between the compressed strip and the untouched neck that is the important bit.

If you think about it the strip itself can't actually grip the bullet as it is bound to spring back a little bit, if anything it will be looser than the rest of the neck.

As I understand it the benefit of the crimp is that it holds the bullet in place whilst pressure builds in the burning powder, then releases the bullet to jump to the lands at a higher and more consistent pressure than would happen by just relying on neck tension.

I've often wondered whether gluing the bullet in place, as is done by the sealant in military ammo, might also have some merit. Has anyone tried ? Maybe try the weaker blue loctite ?
 
That is why I asked, I crimp all my loads, but these will be the first bullets with a cannelure I have used.
With no cannelure the crimp die is the only way to go, but with a cannelure is the seating die a better bet than the factory crimp die ?

Neil. :)

The LFC die is not a replacement for the seating die. Seat your bullet like normal then use the LFC.
 
Strangely I reloaded my first test batches of .222 today, I did not have the set up info for the LFC as it was second hand so used the .308 info as a start point.
Immediately felt this was too much crimp so backed it off by half.
Can someone please tell me the correct start setting?
​thanks.
 
With no cannelure the crimp die is the only way to go, but with a cannelure is the seating die a better bet than the factory crimp die ?

Cannelure on bullet is only of benefit if by good luck it is in the right place for the seating depth that your rifle prefers.

And you trim the cases every time to the same length.

If it is, then crimping using the seating die may work well, and will save a separate process.

If not, then it would be an irritation.

The exception to this is ammo for lever rifles with tubular magazines.

Here the crimp serves a completely different purpose, it is a safety feature to prevent the bullet being pushed back into the case under recoil, or magazine spring pressure.

Here the cannelured bullet combined with a taper or roll crimp from the seating die is the best method. The crimp produced by the Lee FCD isn't necessarily best for preventing the bullet being pushed back into the case.
 
The LFC die is not a replacement for the seating die. Seat your bullet like normal then use the LFC.

Funny old thing, forums, and trying to explain something :doh:

So I'll make it really simple, or try anyway.
Assume bullet is seated to correct depth, which by a happy coincidence positions the cannelure for a perfect crimp.
Now what will give the best crimp, a seating die with the ability to crimp (Lee) or a factory crimp die ?

Neil. :)
 
Strangely I reloaded my first test batches of .222 today, I did not have the set up info for the LFC as it was second hand so used the .308 info as a start point.
Immediately felt this was too much crimp so backed it off by half.
Can someone please tell me the correct start setting?
​thanks.

Pull a bullet and take a look at the groove made by the die. I needs to be distinct, but not over-deep. You can also wreck the case mouths if you crimp too hard.

ISTR Speer do not recommend the FCD because when misused it can damage the bullet due to over-crimp.

It needs a sympathetic touch, can't give you any more precise info, perhaps there is an optimum crimp depth that could be measured with calipers ?

I start with the die backed off a few turns. Insert cartridge and close the press. Screw in the die until it stiffens up as the collet snugs up. This is zero crimp. Open the press, screw in 1/4 turn more, start from there.

Start off with minimum crimp, you can always crimp again if insufficient. As said, over-crimp would be bad.
 
Funny old thing, forums, and trying to explain something :doh:

So I'll make it really simple, or try anyway.
Assume bullet is seated to correct depth, which by a happy coincidence positions the cannelure for a perfect crimp.
Now what will give the best crimp, a seating die with the ability to crimp (Lee) or a factory crimp die ?

Neil. :)

I would suggest the seating die would work very well. Thats the way all factory ammo is constructed. Also saves an additional process. Every extra process introduces variability, KISS.
 
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