Frustrated with crimping using a combination seating and crimping die? Maybe I can help a bit?
The crimper is simply a tapered portion within the seating die. When the casing is sent in deep enough it hits that tapered portion and the brass is pressed in against the bullet in the case of a taper crimp, or rolled into a crimp groove in the case of a roll crimp. There are two main types of crimping dies. Taper crimp dies and roll crimp dies. Their set up procedure is the same. Taper crimp is used for the 45 ACP and other autos. Roll crimp is used on revolver calibers like the 357/38 and 44.
To set up your die, first run a casing up as far as it will go, then screw in the die until you feel it come in contact with the crimping ring. Now back it off 1/8 turn. At this setting it will not crimp. Screw the lock ring down tight but don't set the set screw.
Now set the top punch so that about one third of the treads are in the die for a starting point. Now with a casing that is ready for a bullet, put a bullet on it and run it up slowly to push in the bullet. When you feel it start in, back off and measure your OAL (over all length). You are going to adjust the bullet seating punch to the right overall length, by doing several ins and outs and measuring until your cartridge is the correct length at press full up stroke. If using a bullet with a cannelure or crimp ring, the end of the brass should be in the groove.
Now that your bullet is seated the proper amount, back off the bullet seating punch about 3 turns. Now you will set the crimp. Run the casing all the way up. (Top of stroke) Loosen the lock nut on the die and turn the die in until you get some resistance. This is where the die will start the crimp. Bring the casing down a little and turn the die in a little bit more. No more than 1/8 turn. Now run the casing up. You will feel some resistance at the end. Now look at the finished casing.
If loading revolver ammo with a roll crimp, and your bullet has a cannelure or crimp ring, you should be able to see the crimp. If its not enough, you turn the die in a little bit more and run the round up again until the crimp looks right. If loading pistol ammo and using a taper crimp, you just need to crimp enough to remove the bell. Now set the lock ring and the set screw and run the finished cartridge up all the way (Top of stroke) and screw the bullet punch down to hit the bullet and set its locking nut.
You are now ready to seat bullets, and will not need to readjust the die. You will seat and crimp in the same operation. At this point I must remind you that it is important that all your brass be the same length or they will not crimp uniformly. Measure and trim as needed as you prepare your brass.
On most rifle loads a crimp is not necessary. On the 30-30 with tubular magazine, it is recommended. It is also common practice to crimp rifle loads intended to be fired in semi-autos, and some very heavy recoil hunting rounds. Choose a bullet with a cannelure for these loads.
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