|January 15, 2006, 04:00 PM||#1|
Join Date: January 14, 2001
Location: Alexandria, VA
.32 acp headspacing?
Does the .32 acp headspace on the rim? or on the case mouth?
Cartridge diagrams show the case mouth to be .337
the case base to be .338
and the cartridge rim to be .358.
My problem is this.
Building 32 acps for my colt 1903 Model M, and Beretta M1934
I was using the Lee 3die set...therefore seating and crimping in the same step.
Some (Not most) of my finished cartridges were coming out "Fat" and would not chamber easily or completely.
I reasoned that the answer would be the Lee FCD.
Problem is Lee doesn't make a FCD in 32 acp.
Talking to the Lee people, we decided that I should get the .32 S&W Long (which Lee DOES offer).
I could back out the crrimper (it wouldnt reach the .32acp anyway) and just use the Carbide Resizing ring to iron out my bulge/whatever.
It was even suggested that by inserting a "spacer" between the crimp screw in head and crimper, that I might be able to crimp the acp with the S&W FCD as well.
I got my >32 S&W Long FCD, removed the Crimper portion and tried to "iron out" my "fat cartridges"
It helped but did not completely solve the problem. some would still not chamber completely.
I fashioned a "spacer" out of a pile of washers and got the .32 S&W L to actually crimp the .32 acp.
This seemed to work...but I then realized that the .32 S&W L crimper was a ROLL crimp....and I had always been taught the autos headspaced on the case mouth and should be "taper crimped".
MY fantasy is that the Lee FCD carbide resizing ring is resizing the finished case only to a shade more than .337.
This isn't quite enough for my two .32 acp pieces chambers which are .338 and .337 base and mouth.......and
That the "roll crimp" is taking the edge off the case mouth and allowing the cartridge to chamber completely.
I believe it is working because they are headspacing on the RIM.
Does this seem right to the group?
Is it OK to "roll crimp" my 32 acp
Yes I know that if I was seating the bullets perfectly straight they would not buloge the case...but...couldn't find a "precision guided bullet seater" in .32 acp
An Armed Society,
Is a Polite Society.
|January 15, 2006, 05:06 PM||#2|
Join Date: July 14, 2005
Location: New England
"Is it OK to "roll crimp" my 32 acp"
I doubt it. It's a rimless cartridge, and therefore, unless I'm mistaken, headspaces on the mouth.
|January 15, 2006, 05:16 PM||#3|
Join Date: June 14, 2004
Location: NY State
Actually the 32 acp is a semi-rimmed case and therefore headspaces on the rim. The semi rimmed therefore can be crimped assuming the chamber dimensions are correct ! Colt dimension control was so poor with the 38 Super [also semi-rimmed] that they changed it to headspace on the mouth !!
|January 15, 2006, 06:49 PM||#4|
Join Date: January 15, 2006
Location: Stockholm, Sweden
Actually, the only way that you are going to be able to solve your problem is by determining your exact chamber dimensions (you just don´t want to know all the differences in chamber sizes for this caliber that exist in all the guns manufactured and chambered in this caliber- even by the the same manufacturer!) and from this information choosing a correct case length that will allow you to head-space on the case mouth. Roll crimp is a no-no for this caliber, even with cast bullets.
|January 15, 2006, 08:26 PM||#5|
Join Date: September 25, 2005
Remove the barrel.
Place a sized empty case in the chamber.
Does it stick?
Then it must be your belling, or seating, or crimping operation that causes the malady.
Too much bell, too fat a bullet, or too much crimp may warp a case and cause it to stick.
You don't need fancy crimp dies, just correct your technique.