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Old 11-09-2010, 04:35   #1
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Crimping vs accuracy

Like I wasn't confused enough already. In the Mini 14 talk forum, a question about reloading for the Mini was posted. In the posted responses, Turn-Key says crimping has a great effect on accuracy, dkac2 says crimping hurts accuracy, and steve4102 says crimping helps accuracy. Could you 3 guys please expound a little on your views on crimping vs accuracy? And anyone else who wants to join in. Thanks.

Last edited by higgite; 11-09-2010 at 04:42.
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Old 11-09-2010, 05:04   #2
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I'd like to piggyback a q: to Higgite's here-
Hornady says to adjust the die until the "proper crimp is obtained". If you advocate crimping, what's the "proper crimp"?
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Old 11-09-2010, 06:50   #3
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When Crimping is done right it will improve accuracy, as I said in the Mini forum , I recived 1000 rounds of BVAC reloads (good company) the rounds I shot where initially at a 5-6 inch grouping, after I crimped the remainder, the grouping went to 2-1 1/2 inch groups. I use a Lee Factory Crimp die on all of my rounds, rifle and pistol, with my 308 at 300 yrds you can palce a nickle over the 3 shot group and you won't see the entry holes. Too much crimp is not good and to little why bother, it takes alittle practice to get it right.
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Old 11-09-2010, 07:05   #4
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I have tried both with and without a crimp . My experience is that with a light crimp I have gotten better consistancy in groupings , which in turn gives me better overall accuacy . Using a Lee FCD .
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Old 11-09-2010, 07:27   #5
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Originally Posted by higgite View Post
Like I wasn't confused enough already.

That's alright, I usually stay that way myself

To crimp, or not to crimp, that is the question!
(Just my tribute to the Bard)

Crimping is a weird animal. This same process can hurt or help depending on the bullet you're using and the amount of crimp you use.

John mentioned that using a crimp in a semi-auto is essential, and he is absolutely right. If your bullets are not being held firmly by the case mouth the rounds in the magazine can impact the front of the mag and move the bullet further into the case which can cause higher chamber pressure. Too heavy a crimp can cause the same high pressure problems.

For me, proper crimping is a trial and error process to find out what type of crimp works best for the round I'm developing. As both Amrhein and 67rschev mentioned the Lee Factory Crimp dies are the way to go (or at least a separate crimp die if you don't like Lee's.) When you're seating a bullet and crimping in the same step I just can't get feel of how much crimp is actually being applied.

I've also found times when no crimp at all gives me the best accuracy, but that was in a bolt gun.

I hope this hasn't added too much to the confusion.
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Old 11-09-2010, 08:17   #6
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Some rifles like it, and some don't. The olny to to find out if your rifle likes it is to try it both ways.

The only rifles I crimp for are those that require it due to tube magazines or high levels of recoil (hint on definition of "high", I DON'T crimp for my 375 H&H)
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Old 11-09-2010, 08:44   #7
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Well, if the concern is a "loose" bullet impacting (exceeding) the OAL...and that seems to be the consensus from all I've read online...my (granted) limited experience with my Hornady press tells me there's no way that's gonna happen- at least with what I'm currently using (Winchester brass and Sierra bullets).

I had about a dozen bullets that I needed to pull- so I bought a bullet puller and it took a half dozen sound whacks to get them to come apart. Those suckers ain't moving unless they're fired. So for me, I'm gonna stay in the "no crimp" school. I don't see a reason to risk higher pressures from too much crimp, especially given that I'm an inexperienced reloader.
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Old 11-09-2010, 10:25   #8
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It's more than just the safety of it, which is important in a semi-auto, that prevents overpressures, it's the consistency of bullet release too. For the same reason neck turning improves consistency, crimping does too - it gives each cartridge the same tension as another, and the same all around the neck... more or less.

That's not to say that it's a technique that actually improves the round or improves accuracy, it's just eliminating a factor that prevents the most accuracy from being obtained - the bullets moving, neck tension being unequal, etc.

The highest accuracy actually comes from the least amount of tension and crimp possible. Most guys using bushing dies are now talking about bushings only .001" to .0015" undersize (for brass springback) to exert the least amount of tension on the bullet possible - this would be useless in a hunting or semi-auto though, so we aren't able to utilize this option anyway, but I brought it up to show an extreme in another direction.
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Old 11-09-2010, 12:14   #9
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Question

OK, my take on the whole crimping issue in Bottle Necked rifle rounds.

First let me help calm some of you new handloaders down just a bit. When a bullet is forced deeper into the case by the cycling of the action it is called "bullet setback". This is a bad thing as far a straight walled pistol rounds are concerned and can be catastrophic. Bullet "setback" in bottle necked rifle rounds can cause a "Small" increase in pressure and raise hell with your accuracy and POI, but it is not going to raise pressures beyond safe limits, unless you are already over the top. It's all about percentages in case capacity.

Crimping, I do not crimp rifle rounds with the crimp feature on any of my seating dies. They come with taper or roll crimp along with with all sorts of problematic issues.

For the crimp feature on seating dies to be of any real benefit the bullet should have a cannelure, doesn't have to, but should. All brass crimped with the seating die should also be of the EXACT same length. Just the slightest change in case length can cause problems.

Securing the bullet in a semi-auto is more about bullet creep than it is about bullet set-back. Here, this will expalin it better than I can, from Sierra Bullets.
Neck Tension
When we stop to consider the vigorous (read, downright violent) chambering cycle a loaded round endures in a Service Rifle, it becomes pretty clear it suffers abuse that would never happen in a bolt-action. This is simply the nature of the beast. It needs to be dealt with since there is no way around it.
There are two distinctly different forces that need to be considered: those that force the bullet deeper into the case, and those that pull it out of the case. When the round is stripped from the magazine and launched up the feed ramp, any resistance encountered by the bullet risks having it set back deeper into the case. Due to the abrupt stop the cartridge makes when the shoulder slams to a halt against the chamber, inertia dictates that the bullet will continue to move forward. This is exactly the same principle a kinetic bullet puller operates on, and it works within a chamber as well. Some years ago, we decided to examine this phenomenon more closely. During tests here at Sierra’s range, we chambered a variety of factory Match ammunition in an AR-15 rifle. This ammunition was from one of the most popular brands in use today, loaded with Sierra’s 69 grain MatchKing bullet. To conduct the test, we chambered individual rounds by inserting them into the magazines and manually releasing the bolt. We then repeated the tests by loading two rounds into the magazine, chambering and firing the first, and then extracting and measuring the second round. This eliminated any potential variation caused by the difference between a bolt that had been released from an open position (first round in the magazine) and those subsequent rounds that were chambered by the normal semi-automatic operation of the rifle. Measuring the rounds before chambering and then re-measuring after they were carefully extracted resulted in an average increase of three thousandths (0.003") of forward bullet movement. Some individual rounds showed up to seven thousandths (0.007") movement. Please bear in mind that these results were with factory ammunition, normally having a higher bullet pull than handloaded ammunition.
To counteract this tendency, the semi-auto shooter is left with basically two options: applying a crimp or increasing neck tension


So, crimping is good, but is it good for accuracy, IMO yes, as long as you use the right crimp. What's the right crimp? The Lee Factory Crimp Die. It works with any bullet cannelure or not, case length is not an issue and if used properly can increase accuracy.

So, how much crimp? That's up to you and your rifle. Me, my Browning BAR's like a little more crimp than my AR-15 and my Mini-30 is somewhere in between.

The LFCD is no different than any other technique or tool, it can work wonders or it can cause problems, it's all how you use it and how much time you are willing to test it out.


.
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Old 11-10-2010, 07:35   #10
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Good post, Steve. After re-thinking my post, the fact that they seem tightly seated when using an inertial puller doesn't mean they're not moving a few thousandth's when getting slammed into the chamber.

I'm interested in the Lee crimper- but two questions...
1) I watched the Lee video, and it's every bit as ambiguous as the Hornady one...how does one know when "proper" crimp has been achieved?? Is there some sort of "pullout" gauge that can check the bullet's resistance to being moved in the neck?

2) Are die sizes/threads universal? Will this die thread into my Hornaday LNL AP?
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Old 11-10-2010, 07:40   #11
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I used the LFC die and I lost accuracy,so instead I increased neck tension by turning down the expander ball by 0.002 and I've had no problems and I got better accuracy than I did when I crimped. This was for the mini 14
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Old 11-10-2010, 08:30   #12
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how does one know when "proper" crimp has been achieved??
Trial and error. Start with a light crimp and increase the amount of crimp a little at a time.

Is there some sort of "pullout" gauge that can check the bullet's resistance to being moved in the neck?
Use the rifle and it's action. Load a dummy round(no primer/powder) and crimp with a light crimp. Measure the OAL, cycle it through the action, measure again. If it stayed in place you know that this amount of crimp will hold the bullet in place, if not increase a little at a time. I also load proven accurate rounds with various amounts of crimp to check for any increase or decrease in accuracy.

Are die sizes/threads universal? Will this die thread into my Hornaday LNL AP?
Yes.
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Old 11-10-2010, 21:12   #13
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Here's another one...
Loading tonight for the range tomorrow, I picked up some Remington 62 gr match hp's that are cannelured.

I'm not crimping this time...but this bullet doesn't seem to make sense.

I was surprised to find out that Remington has absolutely no load data for their bullets, so I have to improvise there...great...
What's more puzzling to me is that I "assume" the cannelure is supposed to be in the location of the crimp. When I seat these to an OAL of 2.25-2.26, the cannelure is a full 1/16" of an inch above the brass.

IF I were to crimp these, I'd need to seat the bullet that much deeper? That's one heck of a jump to the rifling, isn't it?
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Old 11-11-2010, 02:42   #14
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Tobnpr
Those bullets may not have been made for the 223Rem case, IOW the canalure may be located for a different 22cal.
EX: most 416cal bullets have the canalure in the proper location for the 416 REM, but it sits 3/16" ahead of the mouth when loaded to the nominal OAL of a 416 RIGBY case (on the other hand, the the loading data was developed at the shorter length)
As far as the jump to the lands goes, it's a old wives tale. It did have some validity back in the black powder, lead bullet, funnel throat days, but you're not talking about loading one of those.
In a lot of chamber/bullet combos, you can't reach the lands and still have the bullet inside the case. Also, letting the bullet gain speed before engaging the rifling is a very old pressure reduction trick (that's how Weatherby can load so hot and why the warning about not using "factory loads" in custom "short throated" weatherby chambers). While not target rifles, the Weatherby's don't do all that bad and there the "jump" is often on the order of a full inch.
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Old 11-11-2010, 05:48   #15
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Interesting...
Well, it's .224 dia., so we're gonna find out today how they shoot...I don't read too much about Rem bullets so we'll see.
We've also got some Hornady, Speer, Nosler, and Sierra in the mix for the day. A veritable smorgasbord...
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Old 11-11-2010, 06:19   #16
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Seating to the lands for accuracy is highly overrated. Sometimes it works and often times it doesn't. Fine tuning OAL for accuracy is one of the last things I do when working up loads. It certainly has an affect on accuracy, but it's minimal compared to powder and bullet selection.

Your Mini has a 5.56 chamber so you are going to have a long jump no matter what you set your OAL at, to fit the mag of course. Load as long as you can to fit the mag and cycle the action. After you find a good bullet/powder combo then you can reduce the OAL in small batches (5) and look for that OAL sweet spot.

Here is a good article by Barnes on OAL vs Accuracy and Pressure. You will see that most rifles have more than one OAL sweet spot, one up close and another with a long jump. Scroll down to "From the Lab".
http://www.barnesbullets.com/resourc...rnes-bullet-n/
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Old 11-11-2010, 06:24   #17
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99% of my 223 ammo goes into a semi auto. I crimp 99% of my 223 ammo, not becuase it gives more accuracy but it gives me peace of mind that the bullets will not work loose in the magazine. kwg
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Old 11-13-2010, 20:42   #18
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With the Lee crimp die, you can see how much the 4 fingers are crimping.

Start with them a little further out, then tighten them a little at a time, compare to a factory round.

At no time should you adjust the die so tight that all the fingers touch.

A bullet with a canlature should be crimped, one without should also be if used in a semi auto.

Any canlature in a bullet hurts the accuracy VS a bullet without one and they say not to crimp a bullet without a canulature. The change in surface disrupts the airflow I'm told, but only a very small amount and it also depends on if the bullet is going supersonic or sub sonic. Supersonic tend to push the air away from the sides of the bullet more than subsonic.

Lots of different info.

I think most people tend to over crimp, which will hurt the accuracy.

Others have said that a proper crimp can help accuracy due to the proper amout of pull on the bullet and they are 100% right.

Go easy, look at factory loaded ammo nd always crimp a bullet used in a semi auto for safety reasons. That's really the bottom line.

I liked the suggestion of trying different amouts of crimp and comparing accuracy, fantastic way to find out when the amout of crimp is correct.

There is a lot of conflicting info on crimping, but do at least put a light to moderate crimp on your Mini ammo.

Best Regards, John K
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Old 02-22-2011, 02:09   #19
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I crimp bullets with a cannelure, and don't with no cannelure. All my scoped rifle loads are sub-moa, crimp or not. (I'd wager my iron sighted rifle loads are also sub-moa, I just can't shoot sub-moa with anything other than a nice Lyman peep.)

I mainly crimp so if I drop my cartridges, the bullets will not slide inside the case.
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Old 03-05-2011, 10:07   #20
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I crimp, because i have the tools to do it correctly and have had bullets backset inside the case. Also grow and lock the bullet into the rifling and pull on extraction. dumping all the powder out of the case. Crimping will reduce case life, the only negative i have seen.
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Old 05-10-2011, 15:45   #21
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I did three extensive tests using a crimping tool set up recently. The three rifles were a 700 in 223, one in 243 and an AR. In the test each was shot with a given powder charge/bullet combo. All I did was vary the crimp pressure on the case using a LEE FCD.

Here is a link to test #3 on a basic stock AR with a randomly selected load. It has links to the other two tests.

Consistent Crimp Test - Finalized - Pic Heavy and Long!! - AR15 Armory.com

I think this will open your thoughts to the effect of crimp and what it does.

Greg
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Old 05-13-2011, 11:56   #22
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I crimp .223 rounds for my mini and AR unless they use bullets that are longer than mag length, 75 gr Hornadays are ment to be loaded long and single loaded.. I do not crimp any other rifle rounds I dont load 30,30 or other rounds for tube mag rifles. No bench resters crimp any of there ammo and they shoot itty bitty groups.
I also dont crimp rounds for my Garand as I have never had a problem with set back.
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Old 06-07-2011, 08:39   #23
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Do some reading on LEE factory crimp dies. There set is a good one. You will need the set to get what you want. == GOOD LUCK ==
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Old 06-07-2011, 16:01   #24
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In reading this thread I can see that the crimp issue has not been put to rest. Some of you crimp, some of you don't crimp. It would appear that we cannot say categorically that either camp is correct. What you are telling me is that it depends on the rifle and it's use. Some rifle/load combos need a crimp and some do not. So a rifleman should test different amounts of crimp from heavy crimp to no crimp at all. Then let the accuracy determine how much crimp, if any, is needed.

The Lee factory crimp will destroy accuracy with cast bullets.

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Old 08-04-2012, 21:01   #25
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Originally Posted by tobnpr View Post
Well, if the concern is a "loose" bullet impacting (exceeding) the OAL...and that seems to be the consensus from all I've read online...my (granted) limited experience with my Hornady press tells me there's no way that's gonna happen- at least with what I'm currently using (Winchester brass and Sierra bullets).

I had about a dozen bullets that I needed to pull- so I bought a bullet puller and it took a half dozen sound whacks to get them to come apart. Those suckers ain't moving unless they're fired. So for me, I'm gonna stay in the "no crimp" school. I don't see a reason to risk higher pressures from too much crimp, especially given that I'm an inexperienced reloader.


Re:.... the best and safest thing to do , is READ" and Follow the information in your loading manuel" on EVERY Cal. your load for . Some require a Light Crimp" , and some such as a 44 MAGNUM Require A HEAVY Crimp ! One should also read in the BOOK" , Why" a heavy crimp is needed for some cal`s. and WHY" a light crimp is to be used on some cal`s , such as the 45Cal. ACP . Without this information and understanding it , you COULD be a danger un to your self , And to Others around you .
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