I began shooting in a Service Rifle league this past summer with a RRA NM AR-15. I also started reloading about 1 year ago.
I have my load to a point of very good accuracy: LC brass, Win primers, 24.5g of Varget with a 69g Sierra Match bullet, @ 2.260".
My question is this: Do you crimp your bullets/brass for Service Rifle Competition? Which of course includes rapid fire (semi-auto feeding).
The 69g Sierra, needless to say, does not have a cannelure.
Thanks, nost.

You would probably get more info in the Reloading forum

^





 

If you don't use Dillon dies then get the Lee Factory Crimp die.  You can apply anywhere from a very light crimp to a heavy one.

I use it on my 270 and 6.8 loads and put a light crimp on both.

I like the added safety of preventing bullet setback or jump forward in my 6.8 AR.  

For the .270 it's not as important but my loads shoot quite well for hunting loads so I'm going to continue using it.

My .223 dies are Dillon and they have a taper crimp die too and I use it as well for the same reasons.

Thanks for your replies. The way I see it, from your comments and that of Lee(included below), the proper crimp has proven to promote accuracy.
By the way, I just crimped 175 rounds of 223 that were on hold until I figured what I wanted to do, with the Lee bottle neck factory crimp die.
N


* Tests demonstrate that even bullets which have no cannelure will shoot more accurately if crimped in place with the Lee Factory Crimp Die.

LEE FACTORY CRIMP DIE


Factory ammunition is often more accurate and better able to withstand rough handling because the bullet is firmly crimped in place. A firm crimp improves accuracy because pressure must build to a higher level before the bullet begins to move. This higher start pressure insures a more uniform pressure curve and less velocity variation. Even powder selection is less critical.

Until now, handloaders seated the bullet to touch the rifling to achieve similar results. This is not always possible nor desirable. The Lee Factory Crimp Die is included at no extra charge with Lee PaceSetter Dies. It's just another added value that only Lee Dies offer.

No one I shoot with crimps their .223.  I don`t even know anyone that crimps their competition .223 ammo

A while back, there was an ad war between Richard Lee and another manufacturer over that statement from Richard Lee.  IIRC, the other reloading manufacturer was against crimping when not necessary and illustrated what happens to a bullet when a heavy crimp was applied ala Lee Crimp Die.  The bullet shown had a nasty circumferential crease that made one question how well a bullet crimped as such would shoot.

I played with roll crimps and taper crimps, and found better accuracy with no crimps.  What I did to ensure proper neck tension was play with the diameter of the expander button in the resizing die.

I have never crimped any of my competition loads, .223 or 30 06. Nor do I know any competitors that do... Not needed.
Mike B

Most SR shooters do not crimp.  You can damage the jacket and it adds a generally unnecessary step.  If you need to crimp for sufficient neck tension, try a bushing die.

That is the impression I get. Although, I don't think a light crimp would hurt my shooting, as long as I don't break
the jacketing. Thanks for all your replies, very helpful.
Nost

I've been loading boat-tail bullets for service rifle for years.

Never crimped.

Always use a good chamfer on the case mouth - inside and out.

This.  crimping as a seperate step i beleive is beneficial. a moderate, consistent crimp will lead to more uniform velociies and more uniform accuraccy.

Yeah, I read the manufacturer's claim.

Show me convincing independent proof.

Stuff like this does not convince me.

I did a moderate test with a crimp test.

I did to commonize neck tension on the bullet (vs "holding the bullet in place")


but I ended up lubing EVERY neck when resizing instead of every 3-4 necks like I used to and saw an accuracy improvement equivalent to the crimp test.

so I managed to eliminate the crimping step

I use an RCBS small-base .223 die.

I know I must have resized 15,000 cases on this die.

NEVER, have I lubed the inside of the case necks.

First off, thanks for all of your replies, it's good to read what experienced shooters have to say.
Why wouldn't an extensive test like the "the effects of crimping on accuracy and velocity test"
be convincig? I have heard other shooters say that crimping has slightly improved their accuracy. When you
think about the crimping making the bullet stay in the case a little longer upon firing, you may get a little more
velocity and accuracy? From all that is said in here, I still like a moderate crimp for security purposes, and I think
it is fair to say that it "shouldn't" hurt accuracy.
thanks, Nost

I bet you get a loud squeak when the expander pulls back through the neck, unless you are using a bushing die.
Also, I bet you are sizing your cases down more than necessary to accomodate the stretch of the shoulder from the expander to fit the chamber.
Borg

Consistent neck tension does that, not crimping.  SR and long range shooters don't crimp.  They use bushing dies if anything.

This is the one I use for crimping:Lee Factory Crimp Die for Rifles
Lee Rifle Factory Crimp Die:
These dies work on a collet principal. As the die hits the shell holder, an internal collet closes in horizontally on the junction of the bullet and case, squeezing the case into the bullet. The LFCD can be setup (wrong) to crush the bullet in this process so you must follow the direction packaged with the LFCD to assure the correct crimp is made. It pushes in four spots around the case and needs no crimp grove in the bullet for successful crimping. It is relatively case length independent (but trim length of the cases after sizing MUST match the specs in the manuals or excessive pressures MAY be generated in the firing of the gun). Heavy crimps can not bulge the cases in the crimp area as happens with standard crimping using the standard seating dies for crimping because the crimping force is horizontal, not vertical.

Lee Factory Crimping Die for Rifles:
*
*
*
Solid Crimp:

*
*
*
This is a before and after photo of a 75gr Hornady HPBT bullet. No damage was done
to the jacketing, but small indentation to bullet. I had a very difficult time removing the round
with my "hammer style" bullet remover.

That just impresses me as completely unnecessary for target ammo.

The only data I have seen was where a guy said he tried it on three different calibers. He experienced a 0.1 MOA improvement on .223 and .243, and a 0.1 worsening on the .308.

None of those numbers are remotely significant.

As noted by a previous poster, the effect is probably neutral.

If you think you need a tighter "grip" on the bullet, you can increase neck tension by reducing your expander ball on your sizing die by a half-thou.

Nostradamus, it seems you made your mind up already to crimp no matter what you heard, so I can help but wonder why would you ask then?

More importantly, regarding your pictures of the Hornady bullet being squished by your crimping method, I would imagine that is exactly why a competition shooter WOULD NOT crimp!!

Good luck to you either way, (though I see you are already set on crimping!). Consistent neck tension is what you should be striving for, not squishing your bullets.
I sure the hell wouldn't want to do that to my bullets before sending them downrange. (expecting the best accuracy I could get out of them!) Try asking Hornady and or Sierra what they think about crimping for SR competition, they'll tell you!
Mike B

I use a lee factory crimp die on 68gr cannelured hornady's with good effect.  I use a VERY LIGHT crimp with a LFCD on 175 SMK's in .308 and found an accuracy improvement and a reduction in velocity standard deviation.  Mind you,  I'm talking about a minimal, minimal crimp,  probably in the neighborhood of 1 or 2 thousandths all the way around.  it leaves a light crease on the bullet when I pull them, but it's so light, it gets ironed out by passing down the bore.  

Don't overdo it with the lee factory crimp die,  they are a strong article and can crimp deeply,  I found that if I raise the ram with a loaded cartridge, and screw down the die till it makes firm contact with the cartridge, then give it about another 1/8 turn - this is for non-cannelured bullets.   On a cannelured round, I go about a half turn.

I haven't made my mind up completely, and if it were to be wrong to crimp, I surely would not do it.  Although, I have yet to hear any evidence that a light crimp
harms accuracy ! I hear evidence that just the opposite happens. Lee Precision, and several other "crimpers", have observed accuracy gains by crimping, minimal
as they may be. There is theory behind it as well: A firm crimp improves accuracy because pressure must build to a higher level before the bullet
begins to move. This higher start pressure insures a more uniform pressure curve and less velocity variation. Even powder selection is less critical.
I know this is Lee talking, butI suspect there is some truth to it. I have yet to hear any theories, or tests that say crimping is bad for accuacy. (maybe I missed them in this post?)
       Unless somebody can prove that crimping is the wrong thing to do, then yes I will probably continue to crimp. I won't crimp like the above photos, but a gentle crimp,
as far as I can see, will benefit in a couple of ways.
thanks, Nost.

Look at this mans credentials and then listen VERY closely to what he has to say. The name of the game in highpower is to attain what he has already accomplished.

Sir, WADR there are a number of issues that are assumed to be true within the context of the statement from Mr. Lee.  It is reasonable to assume that brass used in factory ammo is quite uniform and of equal length.  The same cannot be said for resized cases that will often have different case neck thicknesses, different case weights, and possibly different case length and shoulder set back.  

As indicated by one response to your question there are reloaders that use resizing dies with expander balls fitted to the decapping rod that don't use any case lube on the inside of the case neck.  As Mr. Borg mentions it's likely that particular reloader has some variation in shoulder setback and other case dimensions after resizing.  Most commercially available reloading dies for bottleneck rifle cartridges resize the case neck significantly more than needed.  When the neck dimension is reduced this much the expander ball of the decapping rod has considerable friction between the inside of the case neck and the outside diameter of the expander ball as the expander ball is withdrawn from the case interior.  This friction generally results in some deformation of the case shoulder which means there is now also some variation in the case length.  All these factors related to variations in the finished dimensions of the resized case will result in different case neck tensions when the reloaded cartridge is crimped.  In my experience variations in case neck tension have a detrimental effect on the shot to shot consistancy of the reloaded cartridges.

In my humble opinion the inside diameter of the resized case neck should be between .002"-.003" less than the diameter of the bullet you intend to reload.  The finished length of the resized cases should all be the same as should the shoulder set back.  All these dimensions require specialized tools to measure and you actually have to perform the measurement to know just how much the variations actually are to make an intelligent decision of how to proceed.  To measure shoulder set back I use a simple RCBS case mic and other dimensions I use a dial caliper and ball micrometer.  I use case lube on the inside of the case neck and a carbide expander ball on the decapping rod of my Redding type "S" dies.  In addition I use a case neck expander mandrel to ensure the finished case neck inside diameter is exactly the dimension I want to match the bullets I use.  All things considered in addition to everything else I do in the reloading process crimping really is unnecessary.  JMHO, 7zero1.

When Benchrest shooters will start crimping, I will consider it. If there is any benefit they are the ones who will see it first.

No crimp for me. My sizer die which is a Forster (Bonanza) and it's neck expander leaves my sized brass with a tight uniform grip on the bullet. To force a crimp into a good match bullet that has no crimping groove seems to be a form of madness.
The crimp came about for combat ammunition. Under heavy recoil a bullet could move forward causing possible malfunctions of the weapon.
If you suspect this is happening in your AR, I would try loading at least 15 rounds. Fire all but the last two rounds. The one still in the mag that wasn't chambered, check it's over all length. If it moved, get a new neck expander in your sizing die.

One can always make their neck expander ball smaller, thus providing your case necks to become smaller.  Chuck up the expander rod in a drill press. Run it at a fast speed while holding fine grit emory cloth to the expander ball. Then polish it with crocus cloth while it is still turning. A good set of mics would be handy here!

Dave McGrath

Count me in with the no crimp crowd.
I've never crimped any of my match ammo. My results have been great.
I don't personally know anyone who crimps their match ammo.
YMMV

Another one for the no crimp crowd.  This would be for competition rounds.  I have never had any problems with properly sized brass whether neck sized for my bolt guns or full sized for my auto loaders.  I would say that if you choose to crimp you really need to be consistent as that would be the key to accuracy.  I would probably want them crimped if I was putting my life on the line as in Police, Military Service or possibly hunting dangerous game especially at close quarters with something that is really pissed off and charging or hungry for my flesh.  For me I have only found it necessary to crimp straight walled pistol rounds because of the expanded case mouths.  Since you have already crimped a bunch give it a shot an prove it to your self that it is worth it.  Good Luck.

The ammo I've reloaded with cheap bulk cannelured 55FMJ all got crimped. That's for when the Zombies hit the fan.

I do not crimp match bullets because I don't need to. Have not had any bullet setback issues, and never had a problem during any rapid fire course.

I use a regular Forster seating die for my 60 gr. bullets, and a Forster micrometer seating die for 69 gr. SMK and 68 gr. Hornady. Forster dies do not have a crimp ring, anyway.

But there was so much back and forth a while back between the Crimpers and the Neck Tensioners that I had to test the theory myself, using a Lee FCD to apply a medium crimp on a batch of 69 gr. Sierra Match King, while another batch was reloaded the usual way.

Shot five 5-round groups with the crimped batch, and the same with the non-crimped batch.

Got 5-inch groups at 200 yards with the Lee FCD, and 2.5-3.0 inch groups without it.

But that just proves one point: don't take someone else's advice. Test it for yourself, with the bullets you intend to use, and then you'll know which church to belong to.

There is theory behind it as well: A firm crimp improves accuracy because pressure must build to a higher level before the bullet
begins to move. This higher start pressure insures a more uniform pressure curve and less velocity variation. Even powder selection is less critical.

Someone made the comment that Benchrest shooters do not crimp.  That's typically the case because they use an OAL that jams the bullet into the barrel's rifling.  This has the same effect as crimping in that it holds the bullet in place to ensure consistent powder burn.  This along with consistent neck thickness and tension is what adds up to improved accuracy in their reloads.

Since I do not jam 5.56 reloads, I do crimp.

Art

Total action time for small caliber weapons is about 2.5 milliseconds. For larger calibers, such as 20mm to 30mm, the action time is about 3.5 msec. This includes: hammer fall, primer initiation, propellant initiation, shot start, projectile acceleration and barrel travel, and projectile exit. Peak operational pressure occurs at about 0.5 msec with about 2 msec barrel time.
How long do you think a crimped brass case will retain the bullet against 50,000 psi of pressure?

I think that it is a carry over from handgun reloading. I'm not much of a hand gun reloader but I believe that there are some applications that a heavy crimp improves ignition. There are numerous reasons I don't believe it applies to rifles.

B

To each his own.  My point is not to change anyones mind, simply to add information to the discussion.

Just curious that not a single ammo manufacturer offers un-crimped ammo.

Art

That's because they have to assume that their ammo will be mis-treated by every "Fudd" out there, thrown in the back of a pick-up, in the bottom of a boat, left in the pocket and run through the washer/dryer, and so on.
I don't do any of those things.
'Borg

So what is your source for that info?

B

Almost no highpower shooters crimp for .223.