Questions about crimping.


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slowr1der
April 10, 2010, 10:19 PM
So I've read that you need to crimp rounds if they are a for a pump, semi auto, or lever action. So if they aren't for one of those is there any advantage to crimping them?

My next question is will crimping them change the POI? As in if I shoot some now un-crimped will I have to re sight it in when using ones that are crimped?

My third question is how exactly do I you crimp them? I've read in the reloading manuals about it and still am not sure I get it. Do you screw the screw on top of the reloading die in until you feel it have pressure? Or what do you do? I'm just a little confused on it.

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R.Clem
April 10, 2010, 10:48 PM
Firstly, the crimp ring is in the die, you screw the die down a little at a time to get the desired crimp, (some dies that should have a crimp ring, don't). The best crimp I have found for handgun cartridges that need them, adds another step by way of a Redding Profile Crimp Die. These dies give the same style crimp as what you see on factory ammunition.
From past experience,a crimp is not something that you want to contend with, UNLESS, you are loading for a magazine that puts one case directly behind the other, or it is a heavy recoiling weapon, which will back the bullet out of the case when another one is fired.
Also in my past experience, any changes made from load to load will require re-sighting.

Ray

TRguy
April 10, 2010, 11:11 PM
I crimp my rifle cartridges with a Lee Factory Crimp Die. The premise for me is that crimping the projectile in the case allows the projectile to release from the case at approximately the same or near same pressure point as the rest of the load in the same batch.

Giving me more consistent pressure and hence velocity and consistent accuracy.

Maybe its bunk but I crimp all my rifle cartridges and covering my holes with a dimes says I am not doing it wrong. Is it correct? I don't know, but will keep doing it.

JimKirk
April 11, 2010, 08:11 AM
TR .. how do you check the pressure in your guns?

I know that it is easy to check speed and accuracy.

I know that they made strain gauges for some of the chronographs... just wondering how you check yours?

Jimmy K

loadedround
April 11, 2010, 11:33 AM
Guys, I solved the crimping problem the easy way. I love and shoot many Ruger #1 Rifles and have never crimped my loads...never had a bullet setback either or have to worry about OAL length. However I do trim my cases when necessary. :)

918v
April 11, 2010, 01:54 PM
In self-loading firearms, crimping improves feeding reliability (1) and helps to stop bullet setback (2) if the bullet has a cannelure with sharp/defined edges that can catch the case mouth as the bullet gets pushed deeper into the case. Crimping also improves combustion (3) by creating a mechanical lock between the case mouth and the bullet, but only if it has a cannelure. Bullets without cannelures do not offer the second and third benefit.

James2
April 11, 2010, 09:09 PM
Crimping (http://donce.lofthouse.com/jamaica/crimping.html)

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