The Firearms MagEzine

The Firearms MagEzine
A publication of
CenterFire Central
http://www.centerfirecentral.com
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The Firearms MagEzine is no longer published
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VOL. 2 ISSUE 6 June 1999
Circulation 1275

IN THIS ISSUE

THE EDITOR'S NOTES
By Bill Wade

WHAT'S NEW AT CENTERFIRE CENTRAL
Web Site Work
By Bill Wade

PRODUCT REVIEW
RCBS Precision Mic
By Bill Wade

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A WORD OF CAUTION

CenterFire Central and contributing writers are not responsible for mishaps
of any kind which may occur from use or misuse of data or information
published, electronically or otherwise by CenterFire Central. Activities
involving firearms, ammunition, components and equipment require strict
safety precautions and training which are not detailed herein.

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EDITOR'S NOTES

As I mentioned in the last issue, we had some problems with our server.

The situation has been resolved, however, there are still bugs in the site.

I am working to correct the problems and trying to improve things at the
same time. Your patience is appreciated. If you stumble across a dead link or
something that is not working quite right, please drop me a note.

The new host that I chose is doing a fantastic job. Knock on wood, the site
has not been down for a single minute since the switch was thrown.

This issue of the Ezine is a little light. With the Prairie Dog Conference
just around the corner I find myself spending a lot of time with last minute
details for the trip.

I am excited about the information I hope to share with you in the next
issue, after the conference.

Bill Wade

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WHAT'S NEW AT CENTERFIRE CENTRAL

I have been working on a new section on the site called "Equipment &
Accessories".

The hope is to list all of the products that are currently on the market, by
categories such as Cleaning Rods, Solvents, Lubricants, Etc.

Of course, I will miss some products, but eventually, they will all be
listed.

You may recall that in the March issue, I mentioned that the very same
equip-
ment I started with is still being sold on the store shelves.

That is not likely to change simply from a distribution standpoint. What can
change however, is what our young enthusiasts choose and what they are made
aware of.

Familiarity sells. Period. If you see the same product in every store, next
thing you know, you assume it is good stuff. Maybe it is, maybe it isn't.

The point is; THERE ARE OPTIONS!

The new site section will ultimately list the options and the vendors.

Bill Wade

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PRODUCT REVIEW
The RCBS Precision Mic

By Bill Wade

The RCBS Precision Mic has always intrigued me and had been on my wish list
until Midway put them on sale in May. One more thing scratched off my list.
turns out they are also on sale in June.

Before diving in and buying one for each caliber that I shoot, and they are
caliber specific, I wanted to try one. I ordered the model designed for the
220 Swift.

The tool allows you to obtain very accurate measurements of headspace and
bullet seating depth. Here is a picture
http://www.centerfirecentral.com/images/pmic.gif

The body of the tool reminds one of a short piece of threaded water pipe
that is capped at one end. When I say short, I mean about two thirds the length
of the case you are working with. Simply drop a case (loaded or empty), into
the body, primer end first and about one third of the case will protrude from
the open end of the body.

The tool then includes two oversized caps, used independently, that thread
down over the exposed neck of the case. One cap, referred to as the Headspace
Nut, is designed to stop at the shoulder of the case while the other cap, the
Land Nut, is designed to stop against the ogive of a seated bullet.

The Body of the tool is marked along the length in increments of .050
inches, which correspond with marks around the circumference of the caps which are
marked in .001 inch increments.

Placing a case into the Body and threading the Headspace Nut down over the
case will provide the headspace measurement when the Nut comes in contact
with the shoulder of the case. Simply read the marks to determine your
headspace measurement, which will be the minimum American National
Standards Institute (ANSI) standard for your caliber, plus x number of
thousandths read from the Headspace Nut.

If both the zero on the Body and the zero on the Headspace Nut, line up,
then we are at the ANSI minimum, which in the 220 Swift is 1.8060 inches. A
fired case from my Swift, placed in the Body and capped with the Headspace
Nut threaded down to touch the shoulder, provides a reading of .003. In
other words, my chamber is .003 longer than the ANSI minimum or 1.8090.

The directions recommend setting the shoulder back .001 to .002 inches from
the fired case length so that the loaded rounds will chamber readily under
field conditions. Simple enough, thread the sizing die in until it touches the
shell holder at full ram travel. Back the die out one full turn and size a fired case.
Measure it, if the shoulder has not moved, screw the die in about a quarter turn and
try it again. Repeat this procedure until a sized case measures .001 to .002
inches shorter than the original reading of 1.8090.

The benefit is that you reduce excess working of the brass by only moving
the shoulder back just far enough to chamber easily and you reduce the risk of
excess headspace, which can result in case separation and the dangers
involved with that scenario.

Boy, that was a mouthful.

Ok, now for the bullet seating depth measurement, we switch caps to the Land
Nut. The tool also includes a Freebore Assembly tool, which basically resembles a
loaded round. This "loaded round" however, is completely adjustable and you
don't even need a bullet puller.

The "Bullet" is threaded on to a nylon rod and then seated into a short tube
that resembles a pistol case. The mock primer pocket has been enlarged to
accommodate a hex key, which threads a set screw into the nylon connector, expanding it
so that it is tight against the walls of the "case".

Nylon and steel combined do not offer a lot of sticking power. Seating the
"Bullet" long and locking it into place with the hex key, is basically like seating a
bullet too shallow. Place the "round" in the Body of the tool and thread on the
Land Nut. Thread it down until it comes in contact with the ogive of the "bullet".
They use the example of obtaining a reading like .300.

Since the nylon/steel does not offer much "sticking power", when chambered
in your rifle, the nylon will be forced deeper into the case resulting in a
perfect picture of your "bolt to land" measurement.

Now, carefully place the mock round into the Body of the tool, screw the
Land Nut down over the bullet and slowly come to rest against the ogive of the
"bullet". Read the marks and again, their example, you obtain a reading of .150. Make note
of this number. Now to seat rounds .010 off the lands of your rifle, simply set your
seating die so the resulting loaded round reads .140.

There are major drawbacks to owning such a tool. Now you have real numbers
and can actually play with seating depths until the cows come home or the spouse
comes looking for you, which ever comes first.

The bottom line is, the all so important headspace measurement no longer
needs to be guess work. Find your chamber dimension and always adjust your sizing die
accordingly. Bullet seating depths can be adjusted very easily and tested to
find that perfect setting for your rifle/component combination.

The tool is money well spent. If you hurry, you can still get the sale price
at Midway USA 800-243-3220.

Please note that I am not referencing Midway for their benefit, but yours.
Shop wherever you like.