Taper Crimping my 40 s&w

[troyspinetar]

I'm slowly walking my way through my first batch of hand-loaded cartridges. The prepping, re-sizing, re-priming, mouth flaring, load charging all seemed fairly straight forward. When it comes to the bullet seating and crimping...I'm getting nervous. I completed about 40 rounds. I seated based on loading manual (not exceeding case overall length) I checked with calipers...good. So I tried reading about "how much" crimp to apply. I'm using jacketed bullets. I crimped just enough to take out the mouth flare, and I tested the round by applying pressure to bullet on my bench and re-measuring OAL to make sure bullet is secure. Another check i made was taking the round and dropping it into a field stripped barrel to make sure it doesnt hang up. I can visually see a slight mark around the mouth that the crimp left. Am I safe to keep on going? I've read horror stories of people blowing up their guns due to crimping issues. Any feedback is appreciated. Thanks.

[scoyoc5]

Exactly what I'm going through as we'll...

[troyspinetar]

Exactly what I'm going through as we'll...

YES!!! I'm not alone.

[iusmc2002]

If you drop it into that field-stripped barrel, and hear a good "thunk" of the round stopping, that round will be good to go.  If it was crimped too much, it would also get a little stuck in the chamber when you turned the barrel upside down and dropped the round out. 

[300rum]

You have a pretty wide margin on a stock pistol barrel.  Chamber checking, as you did is what you should do.  OAL as in a bullet set back, double charges, and squibs (barrel obstruction) blow guns up.  Overcrimping can cause overpressure and a case failure if on the extreme end but won't really "blow your gun up".  Undercrimping can allow the bullet to set back, then you can have a KB.   

If you are near the "ragged edge" of overpressure then you might want to be more concerned with crimp.  If you backed it off and are working your way up (as you should be) you are fine.  Certain powders in .40 can be spikey, Clays and Titegroup come to mind.  N320 is an exceptionally clean and safe powder in .40, that's what I use.  WST is good too (but reverse temperature sensitive) if you want to try to save a little bit.       

[troyspinetar]

You have a pretty wide margin on a stock pistol barrel.  Chamber checking, as you did is what you should do.  OAL as in a bullet set back, double charges, and squibs (barrel obstruction) blow guns up.  Overcrimping can cause overpressure and a case failure if on the extreme end but won't really "blow your gun up".  Undercrimping can allow the bullet to set back, then you can have a KB.   

If you are near the "ragged edge" of overpressure then you might want to be more concerned with crimp.  If you backed it off and are working your way up (as you should be) you are fine.  Certain powders in .40 can be spikey, Clays and Titegroup come to mind.  N320 is an exceptionally clean and safe powder in .40, that's what I use.  WST is good too (but reverse temperature sensitive) if you want to try to save a little bit.       

Thanks 300. I'm using PowerPistol. My manual states if remember without looking, 6.1 - 7.2 grains for 180 grain bullet for a general range. I threw in 6.5 to start.

[Heredoggydoggy]

Over-crimping can also cause a round to go too far into the chamber, and the firing pin won't reach the primer.  Sometimes it goes in so far that the extractor doesn't pull it back out!

Worst mishap is when you miss putting a powder charge in a reload.  The primer usually pushes the bullet into the barrel just far enough to allow the next round to chamber.  Then, at best, you "ring" the barrel.  At worst, you blow the gun up, possibly getting injured in the process!

[Fisherdave10]

You don't need to overdo the crimp on semi-auto straight/tapered walled pistol cases like 9mm, .40 and .45.

Neck tension alone from a properly resized case should be enough to hold the bullet in place.

Think of crimping for .40 and similar cases as de-belling the case.  You're just removing that bell to ensure smooth feeding.  These rounds index on the case mouth in their chambers, so it is important your crimp isn't so extreme that the neck slips into the lead or rifling.    Ridiculous crimp should be pretty easy to spot.  You should see/be able to feel a ledge at the case mouth.  The neck shouldn't be dug into the bullet like a roll crimp...

Judging your crimp on bullets... Leaving a mark on plated bullets is okay if it's not too deep.  For jacketed bullets, there should be little to no evidence of crimp.  You can repeatedly load a cartridge into your chamber from the magazine for evidence of problematic bullet setback.  Setback is eventually going to happen with any cartridge, but you can judge if a bullet begins setting back with just 1 or 2 chamberings (bad) or maybe 5-10 (not as bad).  You can also push a finished cartridge against a desk using your hand to see how firm the bullets are set.  No need to go gorilla on it.  Don't worry about it too much.  Too much crimp will usually cause more problems than not enough crimp, assuming you have adequate neck tension.

Dropping the cartridge into your barrel/chamber is known as a "plunk test".  It will show you if you have enough crimp to facilitate hangup-free feeding. 

If you're roll crimping revolver cartridges into a cannelure, that's a different story.

[troyspinetar]

Thanks FisherDave! I'm fairly confident I have the settings correct. I have completed about 250 rounds, checking every possible measurement on each one...I guess it makes me feel better doing that 
Now to go fire off a few! I'm sure my nerves will die down after the first one goes BANG!