[BradS]

I have been reloading for quite some time and recently came into possession of a crimping die for loading my 8MM mauser loads. I was surprised that when I took my favorite load and crimped it, it actually became more accurate. I use 50.5 grains of RL 15 with 150 grain Hornady SP bullets.

I then bought a Lee crimp die for my 30-30 and also narrowed the spread over the same load uncrimped.

Before I head out to pick up a crimp die for my 30-06 and 308 I figured I would put the question out to gather the experience of the reloaders on Shooters Forum. You all have never led me astray so I trust the advice.

How many others are or have been crimping and what have you found? Am I just getting lucky or is crimping a good way to improve the accuracy? I am not sure of the dynamics of crimp vs non-crimp and what impact it should have on accuracy.

Any advice on what I stumbled across here would be appreciated.

Brad S
Hebrews 10:39

 

[Gil Martin]

It depends

I have never crimped rifle cartridges for the 8mm, .270 Win., .280 Rem. or .30-06. To date, I have not seen a decrease in accuracy. I do crimp cartridges fired in my lever actions. So it depends what you prefer and your experiences. All the best...
Gil

 

[TMan]

Before I head out to pick up a crimp die for my 30-06 and 308 I figured I would put the question out to gather the experience of the reloaders on Shooters Forum.

I have crimped/not crimped everything from .223 - .375 on and off for years. Occassionally accuracy is better, some loads are not "good enough" to know, most of the time I think you'll see a slight to moderate loss in accuracy. Most handgun loads require the extra tension to have consistant ignition, another story.

Condider this one, if crimping consistantly improved accuracy in rifles, there would be crimps in every benchrest bullet made.

 

[bsn]

The only rounds I crimp are lever action rounds, personaly I feel crimping is hard on brass. Try anealing your case necks on your 8mm and see if your groups don't tighten up.

 

[marsms]

Doesn't Lee have a guarantee on their factory crimp dies (that they will shrink your groups)? I just did I quick search and didn't find it on their website, but I'm sure I remember seeing it somewhere...

 

[Bird Dog II]

I have only crimped a few times. I think a lot depends on how much pressure you crimp with, but I am no expert on it.

 

[wildhobbybobby]

I crimp every bullet that has a cannelure, for no other reason then that I like to. I have never had a problem with either accuracy or case life.

 

[MMichaelAK]

Doesn't Lee have a guarantee on their factory crimp dies (that they will shrink your groups)? I just did I quick search and didn't find it on their website, but I'm sure I remember seeing it somewhere...

Lee's guarantee is for their Collet Neck Sizing die and improving your groups.

I do use the Factory Crimp Die. I have been using it on my 30-06 ammo since day one and some of those cases are on their tenth reload and I havent had a split neck so in my experience, it doesnt decrease case life.

I use it on lever gun ammo, semi auto ammo and bolt gun ammo. I even use it on ammo for my Ruger single shots. While it didnt make much difference in accuracy with the ammo inmy .375 H&H Ruger #1, it did decrease the spread in fps to less than 26 fps between high and low in a 50 shot batch. I was impressed enough then to buy one for every caliber rifle ammo I reload for and I still do. There is one I do not have an FCD for and that is my .416 Rigby. I asked Lee Precision if they would make a collet die set for me and they said they wouldn't make dies for the .416 Rigby because they felt the die walls would be too thin or something to that effect.

 

[MikeG]

The Lee Factory Crimp die is a wonderful thing for cast bullets. Set the overall length to whatever you want and crimp 'em and go. Very handy. With the nice crimp it puts in the case mouth they won't be pounded deeper in the case during recoil!

I have not used it for jacketed bullets in rifles. As far as accuracy.... may or may not help. You never know. If you have the time why not try it?

 

[StretchNM]

I use the Factory Crimp die for 30-06, 25-06, 22-250, .35Remington, and .44Magnum, the last two because they need it, and I crimp them moderately heavy.

The other ones (30-06, 25-06, 22-250) don;t need it, but I crimp certain rounds when it's shown to increase accuracy. Other times, like Tin Man said, it's too close to call, and sometimes it doesn;t seem to help at all. So on those, I don;t crimp.

You can crimp bullets without a cannelure, just don;t do it heavily. I've never tried to crimp one so deep that it "creates" a cannelure - it just doesn;t seem wise to me to do so. Besides, I don;t think there's a need for that. Crimp just enough to add a little more tension to the neck and bullet.

 

[fremont]

I have been reloading for quite some time and recently came into possession of a crimping die for loading my 8MM mauser loads. I was surprised that when I took my favorite load and crimped it, it actually became more accurate. I use 50.5 grains of RL 15 with 150 grain Hornady SP bullets.

I then bought a Lee crimp die for my 30-30 and also narrowed the spread over the same load uncrimped.

Didn't you already answer your own question?

 

[gunpa]

I crimp every bullet that has a cannelure, for no other reason then that I like to. I have never had a problem with either accuracy or case life.

Why let a cannelure determine the o.a.l. of your cartridge ? The oal of the round would be more of an accuracy issue than a crimp Lever actions and handguns need crimps to prevent bullet jump tieing up a cylinder(revolvers) or shoving the round into the case (lever gun) , but every kind of case needs to be properly resized for correct neck tension or bullet pull. No crimp can make up for sloppy neck tension. I have a brother in northern Montana who has broken the 1000 yard world bench record about 4 times with 3 different caliber rifles and no crimps for any of them. Thats good enough for me. If your boolits are moving back and forth in the case of your bolt rifle you haven,t got enough neck tension. Neck crimps for bolt actions seem a waste of time , IMHO

 

[45_70Sharps]

Lever guns and hand guns. Both need the crimp to keep things together.
But then again I shoot a lot of single shots. I don't like to crimp in most of my bolt guns either. The exception being the 338. I just crimp in that one to make sure that I don't have a bullet moving in the case when it matters and I'm hunting. My other magnums are single shots like many of my guns.

 

[StretchNM]

What happens when you resize brass is that the case mouth is sized smaller than the bullet diameter. When seating the bullet, the case mouth spreads open to receive the bullet under pressure of the ram. The case is to maintain it's elasticity and grip the bullet tightly. This is the perfect world we(?) live in.

In the imperfect world I live in, the bullet is sufficiently tight in the case neck to prevent the bullet from moving during normal loading and shooting. However, the factory crimp die adds that extra tad of tension that is lost during seating. There is some pressure gain and bullet/case mouth alignment occuring as a result of FCD crimping. I don;t possess the knowledge to explain the science behind why it helps achieve more accurate results in some loads while in others it does not. I do possess the actual experience of it, though, so the crimp die can help and, in my opinion, is worth the $11 investment per set of dies.

Fremont hit on something missed: you answered your own question, Brad. It works to improve accuracy on your other loads, so.......... my response is, always get the FCD for each caliber-set of dies.

 

[broom_jm]

I have always worked to find the most accurate load in my guns, without including a crimp as part of the process. I've usually found a recipe I was very happy with, unless there was something about the gun that was not right.

I have never crimped a bottle-necked cartridge, if it was being fed into a bolt-action rifle and rarely even crimp the straight-walled pistol loads, if they're being fired from a single-shot action. Still, this thread got me to wondering about something: Has anyone started with a really accurate (non-crimped) load and made it worse, by crimping?

It seems that all factory loads come crimped, but is that because they might be fired in any kind of action, or because crimping generally improves velocity spread and the accuracy of most loads? Maybe I could find very accurate loads more quickly if a light taper crimp was part of my standard reloading process?

Clearly the very BEST accuracy does not involve any sort of crimp, or the benchrest guys would all be doing it, but if I knew for certain that I could get better groups on average, by crimping, I think I would be willing to take the extra step and do so.

 

[gunpa]

What happens when you resize brass is that the case mouth is sized smaller than the bullet diameter. When seating the bullet, the case mouth spreads open to receive the bullet under pressure of the ram. The case is to maintain it's elasticity and grip the bullet tightly. This is the perfect world we(?) live in.

In the imperfect world I live in, the bullet is sufficiently tight in the case neck to prevent the bullet from moving during normal loading and shooting. However, the factory crimp die adds that extra tad of tension that is lost during seating. There is some pressure gain and bullet/case mouth alignment occuring as a result of FCD crimping. I don;t possess the knowledge to explain the science behind why it helps achieve more accurate results in some loads while in others it does not. I do possess the actual experience of it, though, so the crimp die can help and, in my opinion, is worth the $11 investment per set of dies.

Fremont hit on something missed: you answered your own question, Brad. It works to improve accuracy on your other loads, so.......... my response is, always get the FCD for each caliber-set of dies.

I'm still experimenting with this new toy , but so far the Hornady bullet runout tool that actually lets you adjust excessive runout, appears to work very well in shrinking groups. The only drawback I've found is when short boolits are seated out long , such as 40 gr. in 223. It's very easy to lose neck tension if you mess around.