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View Full Version : Do crimped bullets shoot nice tight target groups?


Centerfire
10-21-2006, 03:57 PM
I loaded up a whole bunch of 223 rounds with Hornady 68BTHP, and discovered upon taking one apart, that I had applied a very visible crimp and bottlenecking of the bullet with my Lee Factory Crimp die.

This makes me wonder if there is reason for concern about how the accuracy might be affected.

I guess I'm looking for you guys to tell me that you crimp your bullets and still get your 1/2" MOA groups on the target in spite of a healthy crimp.....and that you've never noticed a pattern of crimped VS non-crimp groups on your target. I'm not worried about a crimped bullet causing a debate as to wheather it is responsible for opening a group an extra 1/16" of an inch. What I'm more concerned about would be to find out that crimping clearly causes a readilly observed difference and group degradation.

montdoug
10-21-2006, 04:49 PM
The only rifle bullet I have ever crimped was a .22 Hornet. I only did that cause my friend Daryl swears by it and in truth I found no benifit to it at all.(sorry Daryl)
There is no bottle neck case I would crimp with the possible exception of something I was going to cycle through a semi auto. In fact with some high intensity rounds you could cause pressure issues by crimping.
Sorry.
On the other hand I have a shooting buddy that also swears by crimping with his Triple Duce. (I've always wondered about that guy?)
Your very likely to get widely varied opinions here. Anything that squeezes a groove in the bullet can't help accuracy in my opinion.

Daryl
10-21-2006, 05:04 PM
I loaded up a whole bunch of 223 rounds with Hornady 68BTHP, and discovered upon taking one apart, that I had applied a very visible crimp and bottlenecking of the bullet with my Lee Factory Crimp die.

This makes me wonder if there is reason for concern about how the accuracy might be affected.

I guess I'm looking for you guys to tell me that you crimp your bullets and still get your 1/2" MOA groups on the target in spite of a healthy crimp.....and that you've never noticed a pattern of crimped VS non-crimp groups on your target. I'm not worried about a crimped bullet causing a debate as to wheather it is responsible for opening a group an extra 1/16" of an inch. What I'm more concerned about would be to find out that crimping clearly causes a readilly observed difference and group degradation.


: No problem, Doug. I however did find a very real benefit to crimping in both the .22 Hornet and the .218Bee. This was due to the poor shape of the cases and the way they string velocties an pressures due to poor burning of powders on the slow side for them. We used this powder to achieve top-end velocities and accuracy from these two rounds. Velocity extremes went form 250fps down to 40fps. so I'd say it was useful. Accuracy was sub 1/2" in both rifles, well under 3/8" in the Hornet.
: So - Would I crimp anything else?
: You bet - but only straight sided rifle and pistol cases - NO bottlenecks. In the straight or nearly straight cases, crimping improves powder burning and accuracy due to holding the bullet back until good ignition has commensed, at least that is the theory and it seems to work. Bottlenecked cases of modern mfg'r.., like the .223, 222, etc etc, do not need, nor do they benefit from crimping to my knowledge. There may be some instance where it would help, but very careful experimentation would have to be done to prove one way or the other.
:Theory that it won't help is plentiful, but it is jst thoery. Proof is in the testing. It is possible that with some powders, crimping even in a .223 might show benefits, but I'd probably never try it, being satisfied it isn't necessary.

Centerfire
10-21-2006, 05:12 PM
Thanks Mont,

I was very fortunate to have had another gentleman post me this link:

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

This makes a VERY strong case for crimping. I was surprised that there doesn't seem to be one case of a non-crimped load actually being better.

Whewww! Sure glad I don't have to dismantle 27 boxes of ammo!:D

Russ O
10-21-2006, 05:32 PM
That data is Fm 1998, & 10% sounds like really alot, until One looks close @ the numbers. If I were a BR shooter then looks like a thing 2-do. However if just shootin Pd's ,Looks like alot of extra cost=Dies-4-each Cal & time in loading press, unless one was using a Progressive type. The only other reason would B-4 ,Tublar feed gun, [218-B ] comes to mind, so as not to have bullets seat deeper during firing. As I said up Front, My 2˘.

GlennFromVA
10-22-2006, 02:06 PM
I don't know many benchrest shooters (100 to 1000 yards), but the ones I do know don't crimp. If it gave a 10% edge you would think they would all do it. I'm skeptical, but open. I always thought crimping was to prevent the bullet (while in the magazine) from moving when the gun was fired.
Glenn

REM
10-22-2006, 03:02 PM
I am sure that consistant neck tension is beneficial to good accuracy especially in the small calibers. I believe that if enough attention to detail is not used to get uniform neck tension that light to medium crimping will help ofset the uneven neck tension and improve accuracy.
REM

Daryl
10-22-2006, 03:13 PM
I should hav eincluded bottlenecked cases in tubular magazines as well. If I wer to load for my .32 SPL .94, I'd crimp them as is normal for those rifles. Crimping in a tube gun is merely to hold the bullets against spring tension and recoil forces.
: There is crimping and there is crimping. If you destroy the integrity of the bullet, it won't shoot well. In the Hornet and Bee I used a fairly heavy crimp, but it didn't hurt the accuracy in the least, and in fact they shot better due to the crimp. It was merely due to allwing the powder to burn better, no other reason.
: I would not crimp a .223 or other case thinking it would make them more accurate. Take a look at the BR shooters - no crimp, indeed, they strive for a light bullet pull that is exactly the same each and every time. Crimping would add another vaiable that they do not want! For them, it would hurt accuracy.

Centerfire
10-22-2006, 08:04 PM
It seems reasonable to assume that to assure an even starting "pull" from round to round is to provide some kind of a crimp. I especially would not expect my already reloaded cases to maintain the same neck tension from case to case. Don't forget that many of us are using the usual Plane Jane run-of-the-mill Rems, Wins, Feds, cases.

I am not foolish to throw caution to the wind and believe everything or anything I hear, but there is a very strong case being made in that above link that AT LEAST A LIGHT CRIMP SHOULD PROVIDE A SAFE MEANS FOR MAINTAING A GOOD STARTING EVEN PULL. WHILE THE REPORT CLAIMS A STRONG CRIMP WAS MADE, I do not feel comfortable with that as I have observed a mild distortion of the bullet. I will use a LIGHT crimp.

You guys are telling me that some accuracy nuts say "do crimp", while still others say "don't crimp".... I now don't believe that one accross the board policy can be applied I think that variables concerning caliber, bullet style, case neck tension, and the amount of crimp applied, all come into play. (ie:for example I would NOT crimp brand new Lapua 223 cases, as I would expect uniform neck tension right out of the box)

BOTTOM LINE; I'll now use a light crimp on my 223 rounds, but once I have found an accurate load I intend to investigate the matter myself by doing my own testing between crimped and uncrimped target groups of the same exact load.

DittoHead
10-23-2006, 05:02 AM
Didn’t Lee and Dillon have an advertising war about 12 years ago over crimping?

Lee said if we crimped, our ammo would be more accurate, we would be more attractive and smell better in the morning. Dillon said “Phooey!” and the fight was on…

Larry in VA
10-23-2006, 05:09 AM
Didn’t Lee and Dillon have an advertising war about 12 years ago over crimping?

Lee said if we crimped, our ammo would be more accurate, we would be more attractive and smell better in the morning. Dillon said “Phooey!” and the fight was on…

Thought I remembered something about that too, but thought it was between Lee and RCBS. No love loss between those two companys.:rolleyes:

montdoug
10-23-2006, 02:56 PM
There is always the empirical way to answer this to a proven point.
I should take a re-do on the Hornet test now that I have time. The initial one was cursory and a guy should spend a little more time on the issue before passing judgement but only on the straight or near straight walled cases as you mentioned Daryl. With me the issue was that both Anschutz Hornets shoot so well uncrimped why bother? All my bottle neck stuff just shoots to darned good as is, if there were a tenth improvement it would be beyond my trigger yanking ability to spot it.
Plus which it works the brass more and unless there's a real advantage that means more trimming etc and I'll pass if possible. I do of course crimp straight wall pistol, some of it hard. My .44 Mag Shoots 21.5 grains 296 under a 290 grain Hard Cast Gas Check from BRP and I use a heavy crimp with it cause it's a rocker!
The only folks I ever remember really touting crimping for bottle neck rounds was Lee, (the ones that make the crimping dies, could there be an ulterior motive there ya think?). I do by the way remember the crimping wars, Lee lost in my opinion. Just my opinion and all rifles like what they like as we all know.
Daryls point anout holding it in the case with straight walls makes sense as does a bottle neck that cycles through a Lever or Semi Auto other than that I'd have to be shown definitively to buy it.

Daryl
10-23-2006, 04:00 PM
Since much modern hunting factory ammo shoots pretty well, and it is all crimped, there probably isn't much of an accuracy loss, if anything.
: A test should be done, crimped and non-crimped.
: The inital question was will a slight crimp destroy accuracy. To that, I'd have to say no, probably not. There will probably be a load that shoots best crimped, and another than shoots best uncrimped. Testin is the only way of telling what's up with crimping.
: The Lee collet crimper needs no crimping groove, except on perhaps, solid copper bullets.
: Crimping certainly didn't hurt accuracy in my .22 Hornet, not the .218Bee, and it also dropped SD's into the teens. With the .218Bee, the SD's droppd to the low teens, like in 12 and 13, while the Hornet ran 17, 18 or 19. The Hornet, loaded with W296, uncrimped, ran SD's almost as high as Lil'Gun did, when uncrimped. I figure that most folks dont' require the Hornet to maintain accuracy beyond 250 yards, and maybe even closer, so high SD's wouldn't make much difference. For me, it was good to 450 yards and a 150fps spread at the muzzle would give too much elevation at long range for consistancy. Crimping gave me that needed consistancy.
: Again, Lee crimp die is the only one worth considering, in m humble opinion as it is a straight collet crimp, having no vertical movement as the job is being done. This allows any degree of crimp desired, another plus.
: Will it make BR size rounds shoot more accuratly? I still say, ask a BR shooter if thye crimp to improve accuracy.

Chucker
10-23-2006, 06:22 PM
The more you work the brass the harder it gets. Seems like after all the work of sizing, trimming, fireforming, and deburring your brass the last thing you would want to do is shorten the cases life by work hardening the neck. It will split eventually so why accelerate the process.

Just my 2 cents. I never crimp the case necks on high performance rounds.

Chucker.