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Old October 3, 2012, 01:26 AM   #1
Pond, James Pond
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Crimping rifle rounds: am I missing something?

Crimping seems to be my nemesis: either causing me confusion or frustration!!

Anyway, I've been compiling a shopping list of sorts for my planned expansion into rifle round reloading, based on what is on sale and what people here have suggested.

Given that I will be reloading my bought-and-fired Norma cases, I am sort of decided on a neck sizing die to preserve the fire-formed cases' shape, and micrometer bullet seater that doesn't full cases size (seem to have found a few).

However, I don't seem to have found any rifle crimping dies yet, given the recoil, I'd have thought that bullet creep would be a greater problem than in a handgun.

Is this process included in the bullet seater die, or are rifle rounds simply not crimped, relying purely on neck tension?
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Old October 3, 2012, 01:33 AM   #2
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Sometimes crimping can be done with the seating die- with some makes/models of dies. I can't begin to help you with your endeavor to crimp, as I don't crimp any rifle rounds. Is crimping not covered in the instructions and/or other paperwork that came with the dies?

Also, someone here will likely have your brand of dies here themselves and will likely aske what brand of dies you have.
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Old October 3, 2012, 02:43 AM   #3
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It's no different than pistol rounds, you can either crimp in one step using the seating die or in a seperate stage. I usually use a Lee Factory crimp die (so much controversy surrounds this die!) to put a very light crimp on mine. Just like with pistol ammo, you'll find people who don't do it at all.

I find that I have to do it on my semi-auto .308, otherwise, I have setback issues when the round contacts the feedramp.

It's just another reloading variable that needs experimentation.
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Old October 3, 2012, 03:20 AM   #4
Pond, James Pond
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Thanks for the input. I don't have the dies yet: I'm creating a short list.

My confusion may arise from the fact that I don't crimp with my bullet seating die: I use a Lee FCD.

If it is integral to the bullet seating phase, then great: one less thing to buy. However, none of the descriptions specified crimping so I wanted to check.

I think I will be getting these following:

Redding Deluxe Reloading Dies: £65
The set includes Redding full length resizing die, Redding neck sizing die, Redding seating die, A spare decapping pin and hex wrench
(I would just ignore the full-length die)

or

The Lee Deluxe set. This includes a neck sizing collet die, dead length bullet seater, and a full length sizing reloading die (again I'd ignore the full-length). Cheaper at £30, but perhaps a bit less high-spec...

I'm going to forego the RCBS Neck sizing die and Forster micrometer reloading die due to cost and the full length sizing of the Forster.

All mounted on a spare turret for the Lee Cast press.

Quote:
I usually use a Lee Factory crimp die
Do they produce an FCD for .308? I hadn't seen it listed.

Quote:
I don't crimp any rifle rounds.
How is it that the bullets stay put?
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Last edited by Pond, James Pond; October 3, 2012 at 03:42 AM.
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Old October 3, 2012, 07:35 AM   #5
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Quote:
(I would just ignore the full-length die)
At some point you will have to use your FL die as the brass case will continue to grow with each firing and neck sizing.

Is your 308 a bolt action? If so then crimping is not necessary as neck tension is all that is required to secure the bullet.

If it is a semi-auto then you have to forget the Neck dies and FL size every time. I would also recommend a Lee Factory Crimp die for a semi-auto. It not only secures the bullet it improves accuracy.

http://www.midwayusa.com/product/448...308-winchester
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Old October 3, 2012, 10:27 AM   #6
Bart B.
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If crimping rifle ammo increases accuracy, then one believing such should convince the competitive shooters winning matches and setting records without crimping to do so. These people know better than to crimp rifle ammo case mouths onto bullets. Even the military arsenals learned that crimping .30-06 match ammo case mouths degraded accuracy in semiauto rifles; they quit that back then. None of the military teams handloading ammo for their 7.62 NATO service rifles ever crimped in a bullet; they new better and it wasn't needed. Even commercial and arsenal match ammo used in these match rifles didn't have crimped in bullets; their people knew better.

Crimping adds another huge variable in pressure curve shape and size; not good for accuracy. Crimping also distorts jackets without crimping grooves therefore unbalancing bullets; it ain't uniform all the way around; another bad thing for accuracy.

Do what you want with your reloading tools and techniques. If you have to crimp bullets in for best accuracy, then I think you're doing something wrong with your tools and techniques that crimping partially corrects. Use the right tools the right way and crimping ain't necessary.

I wonder why respected suppliers of benchrest reloading tools don't list a crimping die.

And the right one properly set up and used, full length sizing dies produce more accurate ammo than any neck sizing ones do.

Case necks resized correctly grip the bullet hard enough to keep it in place without crimping. Even in heavy recoiling magnums, case neck tension alone's enough to do just fine.

Last edited by Bart B.; October 3, 2012 at 10:37 AM.
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Old October 3, 2012, 01:31 PM   #7
Pond, James Pond
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Quote:
If crimping rifle ammo increases accuracy...
If I read between the lines, I get the vague impression that you don't think rifle round crimping is necessary!!
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Old October 3, 2012, 03:06 PM   #8
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If you are shooting a bolt action rifle then for sure no need to crimp. The neck tension is plenty good enough. In handgun cartridges you want to crimp because you are expanding teh case mouth to ease insertion of the bullet. With rifle cartridges you do NOT expand the case mouth so no need to crimp it back down. Magnum revolvers you want a firm crimp to prevent the bullet sliding out and jamming the cylinder.

Plus in the handgun cartridges a little bullet setback can cause a dramatic increase in pressure. Not so in rifle cartridges. The case is much bigger so the ratio of volume displaced by set back is much smaller compared to handgun cases.

Even in a semi-auto crimping often is not necessary. I load for AR15 and M1 Garand and have never had a problem with uncrimped bullets. They do get slammed pretty good on the feedramp so if you want to crimp it may be a good thing to reduce any stoppages. If you load with a bulky slower powder that is compressed (such as Varget or H4895 in .223) then you definitely won't have bullet setback.

I don't think there is any safety concern regarding significant pressure changes. If you are loading for bolt action then no reason to crimp at all. If loading for semi-auto I would not start off crimping and see jhow it works in your rifle first. Chances are it will feed just fine without crimping.
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Old October 3, 2012, 03:31 PM   #9
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Do you own a reloading manual?

If not, I highly recommend getting one and read it front to back a few times.

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Old October 3, 2012, 03:32 PM   #10
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How about crimping in reduced power loads?
I made some 308’s with trail boss loved the round recoil of a 22 but accuracy sucked and they were real dirty
Think it would be worth it to try it with a crimp?
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Old October 4, 2012, 01:37 AM   #11
Pond, James Pond
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I do shoot a bolt action, so that is one less thing to worry about.

I do own a reloading manual: Lyman's 49th.

I don't have to hand right now, but one reason I had such issues with crimping my .44s was that there was only vague guidance on what crimp was needed in the manual. I got my info here.

This time I came here first and I'm glad I did. I've now got the information I need and I'm now able to order my reloading gear and start to plan my reloading accordingly...
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Old October 4, 2012, 02:23 AM   #12
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For bolt guns, I recommend Lees Collet dies. Excellent results. No lube no muss no fuss.
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Old October 7, 2012, 02:12 PM   #13
Bart B.
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James comments:
Quote:
If I read between the lines, I get the vague impression that you don't think rifle round crimping is necessary!!
That's close. Crimping may be necessary for 35+ caliber heavy bullets in light weight rifles for reliability in functioning. But for the rest of them it's harmful to accuracy. Nobody's ever proved to me that crimping rifle bullets really does improve accuracy when such tests are properly conducted with ammo reloaded with proper tools properly set up and used.

That aside, if one gets no worse than 1/3 MOA at 100 yards, 1/2 MOA at 300 or 2/3 MOA at 600 with crimping then go right ahead and do it.

To date, I've not known of anyone who can do that with all shots fired. This is relative to the largest groups shot, not the smallest ones. Any type of bullet-holding setup in case necks will occasionally (rarely?) make a 3-shot group at 100 yards happen. But that's when all the group-changing variables plus shooter ones all add up to do that. When those variables all add up in the other direction, the group may not be covered with a dinner plate.
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Old October 7, 2012, 04:14 PM   #14
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Quote:
If crimping rifle ammo increases accuracy, then one believing such should convince the competitive shooters winning matches and setting records without crimping to do so.
Naw, Apples to Oranges at best. The BR guys have a lot of techniques that we as hunters and sport shooters could not or would not do. We don't use high dollar BR rifles and they would not dare use off the shelf Hunting Sporting rifle as we do. No, not even apples to oranges.

BTW, just for your enjoyment I did another accuracy test with the Lee Factory crimp die.

Wanna see?

OK. here goes.

I purchased a K of Midsouth's 55gr Varmint Nightmare JHP bullets for about $90.

I decided to test this new to me bullets in my Colt AR both with a Lee crimp and without. My crimp is what I call a Med-Light.

I chose Win 748 as it has worked well for me in the past with 50-55gr bullets.

I fired five rounds at each target allowing the barrel to cool between each five round group. This is the first set of groups.






I then fired five shot groups from the bottom up starting at 26.5gr and working up the target to 25gr. I did not let the barrel cool at all. The only down time between rounds was loading the mag.







As you can see these bullets shoot damn good for cheap bullets and you can see that the rounds crimped with the LFCD outperformed the non crimped rounds.

26gr Crimped is a winner in my book.
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Old October 7, 2012, 07:55 PM   #15
Bart B.
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5-shot groups have about 55% confidence they are what the stuff will do all the time. And the rounds were not loaded blind to the shooter; he knew which type he was shooting; subconcious issues here.

And we don't know how much of those groups' sizes are cause by human variables. Nor do we know the details of tools and processes used to pass any judgement on them to see if all the good stuff for best accuracy was used and done.

Test again with 20-shot groups so they'll be more meaningful.

Last edited by Bart B.; October 7, 2012 at 08:02 PM.
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Old October 7, 2012, 11:48 PM   #16
steve4102
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Quote:
5-shot groups have about 55% confidence they are what the stuff will do all the time
Target 2 is Ten shot groups.
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Old October 8, 2012, 08:41 AM   #17
Bart B.
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Those groups look to me to be 1 to 2 MOA in size.

10 shot ones have confidence levels of about 65%.

Some competitive shooters use the exact same reloading tools and techniques as hunters and sport shooters and shoot groups just as good as the BR shooters do with rifle hardware costing 4 times as much. A rifle that shoots as good as what the BR ones do doesn't need to cost more than 1 kilodollar. And good scopes can be had for under 400.

Again......

Do what you want with your reloading tools and techniques. If you have to crimp bullets in for best accuracy, then I think you're doing something wrong with your tools and techniques that crimping partially corrects. Use the right tools the right way and crimping ain't necessary.

PS: it would be interesting to see what physical differences there were (are?) between the crimped and non-crimped rounds. Bullet runout, case headspace dimension and spread, chamber headspace, bullet release force, case neck centering on case shoulder, etc.

Last edited by Bart B.; October 10, 2012 at 09:32 AM.
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Old October 9, 2012, 07:42 PM   #18
steve4102
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Quote:
10 shot ones have confidence levels of about 65%.
Interesting. How did you arrive at these percentages? What formula or analysis are you using?

Thanks
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Old October 10, 2012, 06:34 AM   #19
Bart B.
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Steve, that confidence level is based on statistical stuff that was well shown in a graph that's no longer available online. It's based on the simple fact that the more shots one puts in a group, the better it represents the accuracy one can expect for all the ammo with that load.

It parallels an old addage of measuring stuff that, in so many words says, if you don't get the same number every time you measure something, either your ruler is broken or technique is poor. So, if one shoots a few or several groups and they're not all the same size (within 5% for practical shooting accuracy work), they don't realistically define the accuracy of the ammo. The more shots per group there is, the higher ones confidence is it represents the accuracy all that batch of ammo has. Arsenals shoot several dozens of shots per test group with small arms ammo so their confidence level's well over 95%. They measure each shot hole's distance from group center then calculate the mean radius; about the best way to measure accuracy.

I may have saved that image and I'll look for it on my older computer then post it for all to see.

Last edited by Bart B.; October 10, 2012 at 09:36 AM.
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