Does Crimping the Bullet make a difference?


September 16, 2011, 05:17 PM
I've been reloading for my 8x57 Mauser and I finally brought the crimping Die for it but my father in-law"Who taught me how to roll your own"asked me why I brought it and I told him about what I've read on the internet,and that it's suppose to give more pressure ect.. and he say's he never use's them.Is it worth going back and Crimping the 50 Nosler 200gr.Accubonds and the 75 200gr. Nosler Custom Competitions I already have loaded?And if they don't do anything why do they make them?

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September 16, 2011, 05:25 PM
I never crimp for bolt-action rifles.
I always crimp for lever-action tube magazines, and sometimes for semi-auto's, though not often.

The only need too crimp in a bolt gun is in very large caliber dangerous game rifles.
There, the severe recoil might beat the bullets back in the cases in the magazine.

I have done some tests over the years in some very accurate varmint & hunting rifles, and so far have never found any instance were crimping improved accuracy to any measurable degree. Sometimes it is measurably worse.

It does shorten brass life though!
The necks will split sooner if you crimp.


September 16, 2011, 05:30 PM
And if they don't do anything why do they make them?Mr. Lee makes them in order to sell more dies. :D

Seriously though, the Lee FCD is great because it is not case length dependent like all other crimping dies. It operates off the shell holder, rather then exact case length.

But all seating dies from all companies have always been able to crimp, if you adjust them to do so.
If you go that route, you need to trim all cases to the same length or you will have problems sooner or later.
But most likely sooner.

Like I said above, some big game hunters like to crimp so there is no chance of a malfunction in the hunting field.


September 16, 2011, 06:36 PM
There are several reasons for crimping:

1. To keep the bullet from moving under recoil. This would not be a reason for crimping 8X57 Mauser loads.

2. To tighten bullets in the cases. This has only been needed in my experience with some Barnes TSX reloads.

3. To improve accuracy. Most of the time crimping doesn't improve accuracy enough to notice. I've found it helps sometimes but not always with Barnes TSX and Banded Solid bullets and it helped for some 45 Colt reloads using cast bullets.

If you're going to crimp, the Lee Factory Crimp Die is the best out there in my opinion.

September 16, 2011, 06:45 PM
For reloading it throws an unneccessary variable into the mix. Unless you have some magic that can guarantee a crimp that creates identical neck tension on every round you're going to introduce a variable.
Logic would dictate that you crimp only for those rifles or calibers that demand it.

September 16, 2011, 07:13 PM
I've always considered crimping to be specific to it's purpose, which in my opinion is to prevent bullets from recoil induced OAL changes. As already pointed out, some firearms require a crimp to eliminate the possibility of bullets seating deeper or jumping up in OAL. But for most bolt actions, a crimp is only going to risk having accuracy issues. Tubular magazines are one of those that I would use a crimp for, because they are very prone to recoil induced effects on OAL.
If you are loading for a bolt action, I would spare yourself the risk of unexplained accuracy questions a crimp may impose. Even when I'm loading brass for high powered hunting rifles, .270 win., 7mm RM, and 30-06 type B.A. rifles that has been reloaded as many as 10 or 11 times and more, as well using high pressure loads, neck tension has still proven to be more than sufficient to prevent bullet set back, or any measurable change in OAL.
Also, some handgun cartridges will need a crimp to prevent bullet set back or from becoming dislodged from the mouth. I've in fact had my moments with .357 mag and 44 mag. bullets jumping out of the mouth. When I'm loading with full house powders for magnum cartridges, only a stout crimp will eliminate the problems encountered with recoil and pressure blow back, that in the past has completely dislodged bullets from the case mouth on occasion.
And to reiterate RCmodel's answer, your standard seating die will produce a crimp if that is the direction your wanting to go in. It only requires that you adjust the die body down until it is making contact with the case mouth, at which point you will adjust it down to the point it will produce the crimp while maintaing seating depth at the seating stem.

September 16, 2011, 07:54 PM
"Does Crimping the Bullet make a difference? "

Nothing is totally predictable; sometimes crimping makes no difference, sometimes it does. When it does, sometimes it's good, sometimes it's not good. Logic suggests you try it yourself and see what it does for you.

Hondo 60
September 16, 2011, 08:01 PM
The Factory Crimp Dies do a good job of covering mistakes.

I've learned from the oldsters here that, if you do it right, 3 dies will not only suffice, but do a great job.

But, I'll admit, I've only been reloading for a couple of years & the first die set I bought had 4 dies.
So all of my handgun die sets have a FCD.

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