Part5 – Seating and crimping

 

Warning – this will only apply to 9mmp loads as it is by far the most reloaded cartridge in SA. Loads discussed are my own. Do not copy them, do a proper safe load development.

 

So in part 1, we resized the case and this caused the case mouth to be a little too small for seating the bullet. In part 3 we looked at flaring the case mouth too easily seat the bullet…reread these parts before you continue here.

 

Now we have a case that is resized, primed, charged and flared. We need to now seat the bullet.

 

Seating the bullet simply means pressing it into the case to the proper depth. Seating depth is important for a number of reasons.

 

The cartridge has to fit properly in the chamber and/or magazine, so it can’t be too long or too short.

The bullet is designed to be a certain distance from the start of the rifling in the barrel. If it presses too far into the grooves of the rifling, high-pressure conditions can result and feeding problems will occur.

Pressing the bullet too far into the case can also create high pressures.

 

According to SAAMI; 9mmp has a max COL of 29.69mm, others state a minimum of 27mm and maximum of 29mm….I have always worked with this. Yes it is possible to go longer or shorter but only do this once you have sufficient experience.

 

Cartridge Overall Length or COL is the length of the completed round from the bottom of the “rim” to the tip of the bullet.

 

If you look at most powder manufacturers data they have suggested COL’s for all of their loads. This is based on the length of the bullet. For instance a flat nose bullet will have a shorter COL than a round nose bullet.

 

How do you determine a COL that will work for you? Start at the magazine, does the cartridge fit and feed without issues from the magazine? Then does the cartridge fit in your chamber. Remove your barrel and drop the cartridge in to check if it fits. (Plunk Test)

 

If it fits in your mag and feed without problems do not decrease the COL. You can later decrease the COL if you need to tweak your load…more on this in our final chapter.

 

Let’s setup your Lee Bullet Seating Die…

 

Make sure you have the correct shell holder installed if you are using a single stage or turret press, same goes for a progressive press. Raise the ram/carrier to the top of the stroke. Keep pressure on the ram/carrier.

Turn the die in until it makes firm contact with the ram/carrier.

Now turn the die out 3 full turns. – Do not skip this part!

If you do not have a seperate Crimp Die, you can now turn the die back in for crimp. A ¼ turn is normally enough…lead cast/coated bullets users do not over crimp!

If you are using a seperate Crimp Die, do not turn the die in for crimp. Leave it at 3 full turns out. Setup explained a bit further…

 

 

Now to adjust the seating depth of your bullet you need to turn the adjustment knob in. You will also use this knob to decrease or increase the depth simply by turning it in or out.

 

Lee recently released a Micrometer Adjust Screw to replace the adjustment knob of your bullet seating die, this gives you the ability to take a reading of your seating depth to record.

 

I have a dummy round that is my required length that I keep on hand to make the setting a bit easier. Insert the dummy round into the die; turn the adjustment knob down until you can feel the seating plug making contact with the bullet. The die should now be set at that length…finer adjustments might be needed later.

 

If you are using a live round, take the necessary care!

 

Crimping the case mouth to remove the flare.

Remember in part 1 we discussed the design of the 9mmp; it has a tapered case. We now need to remove the flare from the case mouth to secure the bullet. This is called a taper crimp and is either done with the Lee Bullet Seating Die or a separate Crimp Die.

 

Taper Crimping is easy and not as involved as a roll crimp as needed for revolver ammo.  You are basically only removing the flare and ensuring you do not have set back. The biggest issue that it can cause is that you could set too much crimp. Too much crimp can cause the peak pressure in the cartridge to jump too high too quick.

 

What is bullet set back? If the bullet is not secured in the case, the action of a semi auto pistol can cause the bullet to be pushed back deeper in the case. Remember that a bullet set to deep can increase pressure.

 

Also if you do not remove the flare you can have feeding issues. A 9mmp “headspaces” on the case mouth, if the case mouth is not correct the cartridge will get stuck in the chamber.

Your crimp on the case mouth should measure 0.380inch.

 

After you have set your crimp, you need to test it.

 

Load a dummy round, no primer or powder. Measure the round. Now take the round and press it as hard as you can into a piece of wood. Measure again and check if the length is the same? If it shortened you probably need more crimp. If not load about 5 dummy rounds, load them in your magazine.  Make sure you do this next bit as safe as possible…follow those 4 rules!

 

Lock you slide back, insert mag and slide lock release the slide…you need the force of the recoil spring for this test! Eject the dummy round. Do this with all 5 and measure again. If the rounds did not set back, you have enough crimp.

 

To check for too much crimp, grab your Kinetic Hammer or Bullet Puller – yes you do need one! Pull the bullets and check for a crimp mark on the bullet. If there is no mark your crimp is fine…if there is a mark you have too much crimp.  For coated bullets make sure that the coating is fine and has not been damaged.

 

Now Lee also has a Factory Crimp Die, that you could separate the bullet seating and crimping operation. Not only does it give a uniform crimp but it also sizes the case again. 

To setup the FCD follow these steps:

 

Turn the die in until it makes firm contact with the ram/carrier.

On a turret or single stage press turn the die ¼ more in, on a Six Pack Pro do not turn the die ¼ more in, you should have set your sizing die already and determined the top of the carrier movement. The FCD must be set at the exact same level as your sizing die.

Turn out the crimping knob; insert a cartridge with the bullet seated. Now turn the knob in until you feel it making contact with the case mouth.

Take the cartridge out; now turn the knob down to set your crimp.

 

Do not over crimp, a ¼ turn is usually enough for CMJ’s.

For coated bullets you have to be really careful with your FCD setup, setting it too deep can lead to the bullet being swaged in the case. This will lead to leading in your barrel and other issues.

 

I prefer to use a separate crimp die in my Six Pack setup.

 

You should now have a perfect reloaded 9mmp. Grab your case gauge or barrel drop to confirm.

 

Up next will be our final remarks and we will have a look at load development.