To crimp or not to crimp that is the question


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shenck
December 28, 2011, 08:04 PM
I bought myself a Stag arms model 3 for Christmas, and have started to load for it. I don't crimp .223 for my other rifle, but not sure what to do for an AR. Some of my manuals say to crimp, some don't mention it at all. I'm just wondering what others do. Thank you in advance.

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Bovice
December 28, 2011, 08:13 PM
Use a crimp.

rcmodel
December 28, 2011, 08:18 PM
Get the case neck tension right, and there is no reason whatsoever to crimp.

Been loading .223 for Colt AR's and Ruger Mini-14's without crimping for about 42 years now.

If the case neck tension is right, and the gun & mags feed right, a crimp isn't needed.
It will take 50+ pounds of force to move a bullet.

Crimping will reduce your case life if that is something you want to do though.

rc

shenck
December 28, 2011, 08:24 PM
Thanks RC I knew you would give me a good answer. I try to avoid crimping rifle ammo when possible. I was fairly sure that recoil would be light enough that bullet jump would not be a problem, But wanted to hear it from someone more experianced with the AR than I am. Thanks again.

35 Whelen
December 28, 2011, 08:30 PM
RC is exactly right. Crimps are only NECESSARY with cartridges such as those fired in lever actions with tubular magazines and heavy recoiling revolvers.

35W

rcmodel
December 28, 2011, 08:32 PM
Recoil isn't the problem in light calibers like the .223.
It's feed impact jamming bullets deeper.

Like I said, if the AR & the mags are right, the bullet doesn't hit anything hard enough to cause setback during feeding.

If you have a bad mag in the bunch, all bets are off.

I'd suggest you just take your dial calipers to the range and chamber and measure a bunch of rounds.

Or look for bullet tip damage.

rc

Waywatcher
December 28, 2011, 08:40 PM
Yeah, what rcmodel said.

Assuming your neck tension is correct, there is no good reason to crimp.

shenck
December 28, 2011, 08:48 PM
I will do that. I have three mags to check out. Thanks again for the advice.

Hondo 60
December 28, 2011, 11:23 PM
When I bought my AR I also bought a book, "The AR-15" by Patrick Sweeney.
In that book, he says that he ran some tests of crimped vs non-crimped reloads.

The crimped rounds were more accurate & had less standard deviation when going across a chronograph.

So therefore I crimp.

P-32
December 28, 2011, 11:42 PM
So therefore I crimp. So Hondo, I guess you are not shooting SMK's.........

Waywatcher
December 28, 2011, 11:57 PM
Or NBTs...

steve4102
December 29, 2011, 07:05 AM
I crimp all my auto-loader ammo with the Lee Factory Crimp die. It works on all bullets with or without a cannelure. It keeps the bullets secure, something neck tension alone cannot do and improves accuracy. Not a bad deal for less than $12.

To crimp or not to crimp, especially with the LFCD, debate pops up quite often around here. There are those that like to crimp and there are those that do not like to crimp. I tested hundreds of rounds both with and without the LFCD and found it works for me. Others here have tested the LFCD and found it to be more trouble than it is worth. Then there are those that have never even seen a LFCD let alone tried one that feel the need to preach the evils of crimping.

It all boils down to personal preference, if you want to crimp do it, if you don't want to crimp don't. Me, I like to crimp. YMMV

steve4102
December 29, 2011, 07:11 AM
So Hondo, I guess you are not shooting SMK's.........

I am.

Sierra .224 53gr MK, 5 rounds 100 yards.
Target on the left is without crimp, target on the right is with a medium crimp with the Lee Factory Crimp die.
http://i2.photobucket.com/albums/y17/steve4102/crimp223.jpg

cfullgraf
December 29, 2011, 07:35 AM
I am not saying crimping or not crimping is more accurate but one 5 shot group is not enough data to come to a valid conclusion.

The more data the better. Statisticians can design an experiment that determine a minimum amount of data required to have statistically valid results.

Again, I am not saying someone has not done a proper study, but every study I have seen, the shooter shoots just one group each for a series of variable and declares the best based on that.

steve4102
December 29, 2011, 08:15 AM
I am not saying crimping or not crimping is more accurate but one 5 shot group is not enough data to come to a valid conclusion.

You are absolutely correct. I should have been more clear, this target is just one of dozens which showed similar results in my Colt AR-15 and my other semi-auto rifles. I tested dozens of loads with and without the crimp in two Browning BAR(30-06 and 300WSM), two AR-15/5.56, and two Ruger Mini-30. The results were not always as clear cut as this target, but in every rifle accuracy was improved with the use of the LFCD. YMMV

rcmodel
December 29, 2011, 11:44 AM
Here is some crimped vs crimped test results I had.
I could hold my mouth different shooting each group and get a bigger difference in group size.

The stuff I shoot with .223 can't seem to tell the differance either.
But hedge balls and beer cans generally don't say much about it, one way or the other.

http://i81.photobucket.com/albums/j219/rcmodel/KTOG/Crimped1.jpg

http://i81.photobucket.com/albums/j219/rcmodel/KTOG/Crimped2.jpg

rc

HJ857
December 29, 2011, 02:08 PM
In this crimp/no crimp discussion there is a phrase that seems to come up all the time - "if you have proper neck tension".

So here's my question, what is correct neck tension? For all you that believe that correct neck tension is all you need, how did you determine correct neck tension? How did you measure it? Where did you get neck tension values? If you don't have correct neck tension, how did you fix the problem?

I am genuinely interested in learning this, because I guess I just don't get how "proper neck tension" is an adequate, all encompassing answer.

ranger335v
December 29, 2011, 02:11 PM
"To crimp or not to crimp that is the question"

Try it both ways, that is the answer.
'

wingman
December 29, 2011, 02:23 PM
I have a stag 3 and don't crimp but I shoot mainly for accuracy slow fire, however If I were loading and storing larger quantities of 223 for plinking and fast firing I would crimp. That is my suggestion, but best to try both for yourself all depends on use.

steve4102
December 29, 2011, 02:29 PM
One way to measure neck tension is to measure the outside neck diameter of a sized case, .250 inches for example. Seat the desired bullet and measure the outside neck diameter again, say .252. I would call this .002 neck tension.

The way to increase neck tension is to reduce the size of the expander button on the sizing die. Using the example above, if you want .003 neck tension then polish the expander down .001. Or remove the expander completely for as much neck tension as the die will allow.

The Redding bushing dies are designed so that neck tension can be increased or decreased with a simple change in bushing size.

I have several Redding bushing dies and tested rounds for bullet movement and accuracy from .001 to .006 neck tension. In my tests no amount of neck tension can hold the bullet as secure as .002 neck tension and a medium crimp with the LFCD. With every increase in neck tension I lost a bit of accuracy as well. .006 neck tension was down right pathetic.

rcmodel
December 29, 2011, 02:35 PM
how did you determine correct neck tension? How did you measure it?
Well, in post #6 I said:
I'd suggest you just take your dial calipers to the range and chamber and measure a bunch of rounds.in other words, look for bullet set-back after chambering but before firing.

I have also used a large woodworkers vice and a bathroom scale to compress loaded rounds until the bullet slips. For most rifle calibers it should be around 40-50 pounds with no crimp.
I have measured asphalt sealed & crimped GI ammo at well over 70.

However, my contention is, that much might be needed in a machine gun, but certainly not in a semi-auto sporting rifle.

But the easiest way is just take your expander button out of the sizing die and measure it with your dial calipers.

It needs to be about .0015 to - .002" smaller then bullet diameter in smaller calibers, to as much as .0025" to .003" smaller in big bores, or it will expand the sized case too much to have good neck tension. My .223 expander measures .2225" and works perfectly.

This is assuming your sizing die is sizing the case below bullet dia to start with.
You also use your calipers to measure that before expanding.

Again, I would look for a .222"+ to .223" case mouth before seating a .224" bullet in it.

rc

RhinoDefense
December 29, 2011, 02:36 PM
So here's my question, what is correct neck tension?
Correct neck tension is the point where the neck holds the bullet so its placement is not disrupted during the loading or unloading sequence.
For all you that believe that correct neck tension is all you need, how did you determine correct neck tension?
Generally, measure several loaded rounds at the neck at several places and take the smallest average measurement. Subtract .001" from that. Use that bushing on your sizing die.
How did you measure it? Where did you get neck tension values?
See above. That's a general rule. Some press a loaded round against a scale to a certain point, say 100lbs reading on the scale, then measure the OAL. If it didn't change, they call it good. Some others use a pull gauge that clamps on the bullet and a dial reads how much force it takes to pull the bullet from its seating position.
If you don't have correct neck tension, how did you fix the problem?
Reduce the neck diameter during sizing until you get desired results.

Problems with neck tension are not solved with crimp, they are solved with the sizing stem on your sizing die. All of my dies are bushing size dies which allows me to provide proper neck tension precisely rather than the crapshoot chances that a run of the mill sizing pin in a standard sizing die.

x_wrench
December 30, 2011, 09:41 AM
c r i m p ! ! !

35 Whelen
December 30, 2011, 10:22 AM
Look, I've been reloading since I was about 18, I'm now 48. I've used dies made by every manufacturer in the U.S. Never, ever once did I have to measure or in any way check neck tension. If when loading bottleneck cartridge cases your bullet are moving, which I highly doubt they are, you have a problem with your dies. In all likelihood the expander ball is too large.

So, if crimping makes you feel all warm and fuzzy, go for it, but do so know it's not necessary if your reloading equipment is working properly.

35W

HJ857
December 30, 2011, 06:23 PM
Thank you gents for the explanations. I'm glad to see that the phrase has some real hard numbers behind it, I was starting to believe that the phrase was just another self perpetuating internet fallacy that had no basis in fact.

jack44
December 30, 2011, 07:11 PM
In a hard recoile rifle like the 1895 45/70 crimp for SAFETY reason dont want your bullet to go in side the case also they say you get better your rifle more
accurate.

steve4102
December 30, 2011, 07:40 PM
I am not saying crimping or not crimping is more accurate but one 5 shot group is not enough data to come to a valid conclusion.

The more data the better. Statisticians can design an experiment that determine a minimum amount of data required to have statistically valid results.

Here is another Accuracy test done by the guys over at the Accurate Reloading Forum. Note the increased accuracy!

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

cfullgraf
December 30, 2011, 08:29 PM
Ok, compelling information. But still not enough data to make the blanket statement "crimped rifle rounds have better accuracy over un-crimped".

Considering it is known that different rifles get better accuracy from different powders, diffrent loads, different bullets, and a host of other variables, why not some do better crimped and some un-crimped.

Walkalong
December 30, 2011, 09:27 PM
But still not enough data to make the blanket statement "crimped rifle rounds have better accuracy over un-crimped".Yep, way to many variables to say one or the other is always best.

rskent
December 31, 2011, 06:19 AM
Rhino said it best
“Problems with neck tension are not solved with crimp”
Have a great Day:)
Steve

Walkalong
December 31, 2011, 09:16 AM
“Problems with neck tension are not solved with crimp”Which is 100% true.

steve4102
December 31, 2011, 10:54 AM
Ok, compelling information. But still not enough data to make the blanket statement "crimped rifle rounds have better accuracy over un-crimped".

True, but it is compelling enough to disprove the blanket statement "crimped rounds will distort the bullet and degrade accuracy", yes.

I will go out on a limb here and say that without a doubt (blanket statement) the use of the Lee Factory Crimp die improves accuracy in MY semi-auto rifles. YMMV.

lead slinger
December 31, 2011, 11:38 AM
I crimp everything I reload weather it's a feeding or just to keep all my ammo on a even plain. I pick up alot of range brass and alot of the 223 I get the bullet just drops right though the case so I do a two stage decap/resize then it run it though a lee neck sizing die

EddieCoyle
December 31, 2011, 12:13 PM
A crimp will help even out groups when you're using mixed brass (mixed headstamps, lengths, and # of times fired).

I could find no difference between crimped and uncrimped rounds when my brass was sorted by headstamp, number of times fired, and trimmed to the same length.

As far as increasing neck tension goes, if you undersize the necks to more than about 0.0025" under bullet diameter, you're wasting your time.

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