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3 die set vs 4 die set for Lee press...reloading.

18K views 8 replies 8 participants last post by  jknova 
#1 ·
I have a book on order by Lyman regarding reloading. What exactly is the 4th die?

Thanks
 
#3 ·
Just by asking this question shows that you are new to reloading. This is NOT a bad thing. We were ALL new to reloading at one time or another. The factory crimp die will give you more latitude later when you get used to what you can do and how to do it. In a nutshell, it gives you more control over the amount of tightness exerted by the end of the shell on the bullet. Halfway pretty much allows your brass to last longer. Max tightness gives you more pressure but "might" weaken the brass to the point of rendering it unusable before it's time. This is NOT a hard and fast rule BUT the difference between the 2 extremes could be 5 or 6 uses to 15 uses or more. The quality of the brass also plays a big part. First things first. Start reloading and get good. After that you can experiment.
 
#4 ·
Die #1 - resizer and decapper
Die #2 - "bells" the mouth a little to make it accept bullets more easily
Die #3 - seats the bullet
Die #4 - crimps the brass. Adjusts between a light "taper" and a tight "roll" into the cannelure

Without die #4, your crimp will come from the seating die and has less precise controls

Get carbide dies when possible, as it lets you skip case lubing.
 
#8 ·
If your using a rifle with a tubular magazine you need to crimp your brass to keep your projectile from being pushed in too far by the magazine spring.

I don't believe in crimping because it weakens your brass and you can get better accuracy without it.
 
#9 ·
I assumed you are talking about pistol dies, since 4-die sets are more common with pistols than with rifles. Correct me if I'm wrong.

Conventional wisdom is that the heavier the bullets are in grains, and the heavier the gun's recoil is (muzzle energy), the more crimp you need. The reason is that inertia can work the unfired bullets out of the cases. This is true in most designs. Picture a .44 Magnum revolver while the gun is firing, for example. The powerful round drives back on the frame, pushing the gun against your hand, with the muzzle pointing up. While this is happening, the other (unfired) rounds get yanked backward by the cylinder pulling on the rim. The lead bullets are yanked backward by their contact with the case that they are seated into.

A heavier bullet has more resistance to being moved, and heavier recoil produces a stronger yank. The result can be bullets working out of the case partially or entirely. The mechanism is exactly like what happens in a kinetic bullet puller, though the force is (presumably) less.

Philosophies differ on whether this is a real-world problem or a theoretical problem.

The other reason for crimp is that in some guns, uncrimped bullets may not feed as reliably. Then again ... overly crimped bullets may not feed as reliably in other guns.

I tend to apply a medium crimp, and I've had good results, but I do wonder sometimes if I might be better off with a light crimp.
 
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