Bullet Crimp

 Crimping Jacketed Rifle Bullets

Setting Your Seating Die to Crimp the Bullet

Commercial .223 Remington


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We will create a fairly detailed checklist on adjusting a seating die to proprly seat and crimp a jacket bullet with a cannelure ring.

You will need:

  1. Reloading press
  2. Reloading Dies ( RCBS .223 Remington in this example.)
  3. Appropriate shell holder
  4. Expendable cartridge case. You will very likely damage it and may ruin it completely.
  5. Appropriate bullet with a cannelure groove.
  6. Magnifying glass - as powerful as you can find. 8 to 10x is excellent.


The cartridge case should be full length resized, unprimed and expendable. You will very likely damage it slightly but you may actually destroy it.




Left: Dog Town 55gr .224 Spitzer. ( Midway USA house brand )
Right: Remington factory loaded .223 55 gr soft point.

We will be adjusting the die to seat and crimp the Dog Town bullet on the left.
.223 bullet cannelure groove 
The first step is to raise the ram of your press to its highest point of travel. Handle all the way down.

Then screw the seating die into the press just a few turns.

Lower the ram and place a resized, but unloaded - no primer, no powder cartridge case into the shell holder.

Raise the ram all the way back to the top of its travel.

With the cartridge case in the shell holder, raise the ram back to the top of its travel.

Screw the seating die into the press until the crimping ring just makes contact with the mouth of the case. This must be done by feel. It will be easy to tell when to stop because the die will turn very easily, then suddenly it will stop.

Back the die ut abut 1/8 turn then screw the lock ring down to hold the die in this position

Back out the bullet seating stem all the way so it will not touch the bullet when the cartridge and bullet is run into the die.

Place the bullet on top of mouth of the cartridge case and raise it into the die to the top of the ram's travel.

Screw the seating stem back into the die until it just touches the point of the bullet.

Lower the ram and screw the seating stem about 1/8 inch further. This should seat the bullet into the cartridge case neck about 1/3 of the way to the cannelure groobe.

Now you are on your own.
Lower the ram, screw in the seating stem a little and then raise the ram to seat the bullet a little deeper. Repeat this step until the mouth of the case covers about one half to three fourths of the cannelure.

Now back the seating screw back out of the die.

Remember that at this point, the die body is about one eight of a turn away from the mouth of the case. Run the case with the bullet seated back into the die and screw the die back in just until it stops when it contacts the mouth of the case.

We are now at ZERO crimp.

Your seating die is threaded 7/8x14. This means that it is 7/8" in diameter and 14 complete turns will advance it 1" into the die. One complete turn of the die will move it into the press by 0.0714 inches. One eight turn will  move it .009 inches.

My experience ( With RCBS dies only. ) is that one half turn is about the minimum that will apply any noticeable crimp. Since I don't know what your dies will do, turn the die into the press 1/4 turn and raise the ram to its full extend.  You will feel pressure as the cartridge mouth contacts the crimp ring.

Remove the cartridge and check the crimp under a magnifying glass.

Here are examples of what you are looking for:   
This is the bullet seated with the die backed out so the case mouth does not touch the crimp ring.   Bullet - No Crimp
Here is the same bullet as above with the searing die turned in exactly one half turn ( 0.036" ) from the condition described aboe as ZERO crimp.  Bullet Crimp 
Here is a cutaway view of the same bullet crimped to 7/8th turn of the die. ( 0.0625" )This is about one eight too much. See the next view Bullet Crimp 
Same crimp as above before the cutaway was made. Note this crimp buckled the body of the cartridge case.  Bullet Over Crimp 























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