We have been having a steady flow of "9mm leading and hitting sideways" sort of threads, so I thought it might be useful to report what I just did to check out my "new" Walther
P1 (P38 w/aluminum frame) 9mm handgun before shooting boolits in it.
First, I had fired about 20 rounds of factory 9mm ball ammo through the pistol, just to
see if it would work properly and how the accuracy was. No problems, and I was pleasantly surprised that the trigger was decent in both SA and DA modes, and the
sights are not at all bad.
First, let's clean the gun up a bit. Brass brush and a couple patches, nothing big. Now,
I picked up a Lee 358-105-SWC boolit that I happened to have handy and a 1/4" steel
rod with a .25 ACP case permanently jammed on one end. I dismounted the barrel
and dropped the boolit into the chamber, and drove it through the lubricated barrel with
a small brass hammer. Before it miked at .359 x .360 and after, two rifling grooves
were .3585 and one was .358, so the bore is a good bit oversized, fairly common
in European 9mms in my experience.
So now I take a case that was fired in the gun and chamfer the mouth and clean it
inside with a brass brush and check the inside with my pin gauges. A .356 (minus)
pin gauge will just barely enter the fired case mouth. This is worrisome because it is
pretty clear that I will need .359 boolit or larger to make this one work, and now there
is a question of whether the chamber will accept (and release when fired!) a loaded
round with a .359 boolit seated. I will start VERY low and see if the chamber will
safely release the fat boolits.
So now, I need to make up a dummy round and see how it will chamber with a .359
boolit seated. I size and expand a case with my single stage 9mm die set (I have a
Dillon 550 setup, too) and seat a .359 Lee 358-105-SWC boolit to the crimp groove
and then run it into the TC die. I drop the dummy round and it chambers up until about
1/8" is protruding at the back. Since I don't know much about the P38 design, I slip
the slide onto the barrel and close it all the way, noting that the breech face is recessed about 1/8" into the slide, so the round is fitting the chamber just fine - good news!.
Next, I want to see if the brass is sizing down the .359 boolit when it is seated. I
measure the expander in the die set and it measures .3535, so there is some concern
that the expanded case may size down the boolit as it is seated.
I also inspect the lead shoulder of the boolit which is protruding from the case, looking
for rifling marks. I see nothing, also good. If I was seeing rifling, or the round would
not fully seat with 1 lb or less force, I would seat the boolit deeper until it would. TC
setting is also a controlling factor in the dummy round seating properly. Both are OK
for my dummy round.
Pulling the seated boolit from the dummy round is next, and it still mike's out at .359, which is great news. So with my std air cooled wheel weights with this Lee boolit,
unsized at .359 and seated with my normal single stage press dies, I can expect to
deliver a boolit that is at least 1/2 of one thousandth of an inch larger than the
groove diameter. I hope that is enough, and it likely will be.
So - now I know that I probably need fatter boolits in this gun than my normal .357
or .358 diameter that I use in with my Lee 356-120-TC mold which is my most
commonly used 9mm boolit. I will try the .358 version of this one and see if it is
big enough to work in the .3585 groove diameter barrel without leading. I won't
be suprised if it is not big enough.
So - if you are starting out with a 9mm this is the path you should take.
1. Slug the barrel, and measure groove diameter with a MICROMETER. A caliper is
typically only +/- .001 or even .002" accuracy and this isn't good enough for this
job. You need a micrometer with .0001" accuracy for this job. Enco tools
online frequently has them on sale for under $35.
2. Plan on using a boolit about .001" larger than groove diameter, and you might even need .002 larger.
3. I recommend the two Lee designs 358-105-SWC and 356-120-TC used with
NRA 50-50 lube. I do not recommend the tumble lube designs from Lee, although
some have had success with them, many have had serious problems in 9mm. The
Lee Alox tumble lube system is marginal, but very cheap to get started in, a signficant
advantage for the new caster. It seems to work most reliably in lower pressure and velocity loads.
4. Make a dummy round to set the LOA and degree of taper crimp (TC), and see
whether a case with a boolit the correct diameter will chamber properly. Boolit
diameter MIGHT be too large to chamber, and LOA and TC are set to work with your
chamber.
5. Pull the boolit from the dummy round and make sure you have not sized it down
during the seating process.
If you follow this routine, you will have a good chance to have good ammo which
is accurate and does not lead, right off the bat. Also, do not think that you need a
super hard alloy or water dropping to harden them for 9mm. Air cooled wheel
weights will be just fine. In fact, too hard and too small are the root cause of most
9mm problems with boolits.
Bill