Are any of you using pistol brass with *1776* Headstamp?

[lewmed]

 I recently set up one of Dillon 550's to load 380 acp using RMR 95 gr fmj bullets and range pick up Winchester and Fiocchi brass and it all passed my Wilson case gauge and plunk test. When I switched to new virgin 1776 brass not a single round would fit in the case gauge. I checked the thickness of the range pickup brass and it was all around 0.009" at the mouth the new 1776 brass is 0.0115" the rounds loaded in the new brass do pass the plunk test but just barely.

[Wobbly]

Wall thickness should not matter. First of all the wall is a varying thickness and you didn't show us where you measured. Secondly, the Sizing die works on the outside of the cartridge case to make all cases a uniform outside diameter. It's the outside of the cartridge that interfaces with the chamber.

Then the belling process expands it again to assist the bullet seating. This is later closed back with the Taper Crimp die.

Chasing An Issue

• First and foremost we only believe what the barrel's chamber tells us about the ammo. A case gauge is simply an assistant to the barrel when it comes to measuring cartridges. A gauge is only a 'quickie test' for expediency. The real question is... what does the barrel say ?



• Of course the case mouth expands due to bullet insertion. If your bullets are all 0.355", then things should be good as long as the Taper Crimp action closes the case mouth back up completely. What is the case OD right at the first 0.03" of case mouth ?



The case has already been completely Sized. The only thing that has really changed is the case mouth diameter due to Belling, but that change should have been totally corrected by Taper Crimp. Going by the SAAMI spec.... if you're not seeing diameters if 0.372" to 0.373" AFTER Taper Crimp, then your crimp die is set incorrectly. This is regardless of whether you use a separate Taper Crimp die, or add your Taper Crimp in the Seating process. The crimping process is there somewhere.

Chasing this last adjustment is why most reloaders prefer to Taper Crimp using a separate die. That is not always possible or affordable. I understand. But the action is there somewhere and making that adjustment is always tedious. Lee instructions advise you to use 1/2 die turns; I would advise you to use 1/10 die turns. And then when you find the correct setting, lock it in place with a Hornady lock ring like this...



Such a sophisticated lock ring is the only way to insure that your fine adjustments are conserved and maintained, should the die ever be removed from the press or the 'tool head' (aka 'turret').

(Edited to include the SAAMI cartridge specs for 380Auto.)

[lewmed]

 Like I said I took the measurements at the case mouth. My concern is the extra case thickness times two is an extra 5 thousands of an inch in case width. That gives a much smaller margin of error than I am used to with once fired commercial factory brass. I did my plunk test with a clean pistol barrel and found a few rounds were a bit tighter than normal add a bit of carbon or unburned powder to that chamber I could have issues.
 I may be over thinking this issue a bit I have been accused of analyzing until I paralyze.

[Wobbly]

And like I said...

The only thing that has really changed is the case mouth diameter due to Belling, but that change should have been totally corrected by Taper Crimp. If you're not seeing diameters if 0.377" to 0.379" AFTER Taper Crimp, then your crimp die is set incorrectly.

You haven't given us that dimension.

[lewmed]

 After a light taper crimp the *1776* loaded 380 cartridge measures .3775" at the case mouth without making any changes to my dies a cartridge made from Federal, Fiocchi or Remington range pick up brass measures .375" and will pass both the plunk test and the Wilson case gauge.

[Wobbly]

After a light taper crimp....

There's no such thing as light, medium and heavy taper crimps. There's only correct and incorrect. To know this you need to compare your readings against the SAAMI spec for your cartridge. That spec is on page 42... HERE.

Here I have to back up and edit my own comments. SAAMI case mouth dimensions for this cartridge are 0.3731in. (This should be in your load manual.) That means the correct theoretical taper crimp is going to be in the neighborhood of 0.371 to 0.370in, and not larger than SAAMI's 0.373in.

...the *1776* loaded 380 cartridge measures .3775" at the case mouth without making any changes to my dies a cartridge made from Federal, Fiocchi or Remington range pick up brass measures .375" and will pass both the plunk test and the Wilson case gauge.

You seem to have a "run-on" sentence. Do you mean...

After a taper crimp the *1776* loaded 380 cartridge measures .3775" at the case mouth without making any changes to my dies. A cartridge made from Federal, Fiocchi or Remington range pick up brass measures .375" and will pass both the plunk test and the Wilson case gauge.

• Going by the specs, your TC die should be set to deliver cartridges with a case mouth diameter no larger than 0.373in. Again, that means the correct theoretical taper crimp is going to be in the neighborhood of 0.371 to 0.370in. The root issue then is that you are not loading by the SAAMI cartridge specs.

• Your barrel may accept larger, but that would be a special case. You can certainly make a series of incrementally increasing cartridges to measure and determine that dimension. The Taper Crimp die setting could then be set to the 0.374/0.375in range due to your specific chamber, but this remains to be tested and verified.

• Additionally due to the dimensional differences, I will point out that if you choose to crimp in the 0.374/0.375in range, you should not assume you can shoot this ammunition in other 380Auto guns.

Hope this helps.

[Bret]

After a light taper crimp....

There's no such thing as light, medium and heavy taper crimps. There's only correct and incorrect.

This is spot on correct.  I've read things such as "light taper crimp" and "firm taper crimp" in more reloading manuals than I can remember.  Statements such as these are wrong and misguide reloaders, myself included.  I think the primary reason that people get confused about taper crimping is that the term taper crimp is a misnomer.  Unlike a roll crimp, it's really not a crimp because a taper crimp isn't supposed to help hold the bullet.  Its purpose is to eliminate the remaining bell left from the belling step so that the case wall is parallel with the side of the bullet.  A better term would be debelling.  In reality, there's not enough taper crimp, just the right amount of taper crimp and unnecessarily smashing the cartridge.

I found a way to determine if I have just enough taper crimp without overdoing it.  I use a dial caliper for this.  Start with a cartridge that's complete (with the bullet seated) except for being taper crimped.  Use the dial caliper to clamp the cartridge about halfway up its body.  Then pull the cartridge through the dial caliper towards the cartridge's case mouth.  Right as you get to the case mouth, you both feel more resistance and see the measurement on the dial increase.  Your goal is to eliminate this increased resistance at the case mouth and the measurement increase on the dial.  Next, put a cartridge in the shell holder and raise the ram all the way up.  Install the taper crimp die and turn in down until you get resistance.  Lower the ram and turn the taper crimp die down 1/4 turn more.  Raise the ram and you should feel resistance as the cartridge enters the die.  Repeat the procedure of pulling the cartridge through the dial caliper.  As you repeat this process while turning the die down a bit at a time, you'll feel less resistance as the cartridge is pulled through the calipers and the measurement increase on the dial caliper will decrease.  Keep repeating the process until there is no additional resistance as the cartridge is pulled through the calipers and there is no measurement increase on the dial caliper.  When this happens, you're done setting the taper crimp die.  If you turn the taper crimp die down more, you're just smashing the cartridge.  Lock it in place with the Hornady lock ring that Wobbly suggested.  Note that if you used mixed cases from different manufacturers, it will be significantly more difficult to get consistent results.

There's one final point that I think is worth mentioning.  If you use a bullet that has a rebated base, you don't need to bell the case mouth.  Because of this, taper crimping isn't necessary in this situation because there's no belling to remove.