RAVEN EYE CUSTOM RIM
THICKNESS MEASURING TOOL
A must have for any
owner of a rimfire rifle that wants to reduce group sizes by
increasing accuracy !
According to Eley, the manufacturer of the highest grade rimfire
ammunition available
(used
in the Olympics), the single most important factor in rimfire accuracy is:
the thickness of the rim.
The kit includes the following:
Contents:
1 Rimfire rim thickness measuring gauge for 22MAGNUM and 17
HMR
4 Target
dots
1 Set
of instructions
NOTE: In order to measure the rim thickness,
you need the rim thickness measuring gauge AND
a dial indicator.
A set of
calipers may also be used, but a dial caliper is highly recommended.
These can be purchased
for as little as $10 for one with 1/1,000"
(0.001") precision, or for around $40 for one with a 1/10,000"
(0.0001") precision.
I recommend
one with a precision of 1/2,000" (0.0005"), which cost around
$30. Complete instructions are included in the
gauge. However, if you just can't wait, send
me an email and I will tell you what type of dial indicator to look for.
This gauge has
been designed to measure the rim on 22 Magnum and 17 HMR
ammunition, but will also measure 22LR and 17HMR2. However, best
results for the 22LR and 17HMR would be had with the 22LR and 17 Mach 2 gauge sold in another auction. Each gauge is optimized
to measure a specific cartridge. See my other listings for details.
GROUP THERAPY: Have you ever had a flyer?
It would have been an amazing group except
for that one shot. The first shots made a single ragged hole. But
THAT shot was off just enough to ruin the group.
Did you flinch, jerk the trigger, or time
your breathing wrong? Who knows, but in the end you just missed
making that perfectly tiny group.
Was it your fault, or was there something else
that was a factor? Could it have been the ammunition? YES! But, on that group, you'll never
know. Hopefully this didn't occur during
the final round
of a benchrest competition, or when you're at the
range bragging to your friends about how accurate your new rifle is!
With all the money that is spent making our
rifles more accurate, it makes sense to examine the ammunition we use as
well.
From now on, make sure you
own the tool that will help reduce the likelihood of having an ammo related
"flyer".
Machined from aircraft strength aluminum, then
hard anodized for a lifetime of use.
Made in the USA! Not an import!
So why is the
rim thickness so critical?
Inside the rim of a rimfire cartridge is a
percussion sensitive compound, the primer. When the rim is hit by the
firing pin, the primer literally
explodes and
ignites the propellant. The initial jump
of the bullet, caused by the primer, before the rifling is engaged is a
critical stage for accuracy.
This stage is directly influenced by the amount
of primer present.
The rim thickness varies even within the same
box of ammunition. Manufacturing processes get the dimensions similar,
but not exactly the
same. The
differences we are talking about here are only a few thousandths of an
inch. A small difference in thickness has a proven effect
on accuracy as
determined by top benchrest rifle champions.
How much
difference can there be?
Manufacturing methods have improved
dramatically over the last twenty years, however there
are still limitations to their ability to produce
geometrically exact casings. A typical rim thickness can be 0.037"
(approximately 1/32"). Within a typical box of ammunition, you will
find
rim thicknesses
between 0.036" and 0.040". More expensive ammunition tends to
be more consistent, however variations exist even in
high
end
products. Without a measuring tool, you have no way of knowing what
you have.
When you consider that the brass
casing has a thickness of around 0.010", and that there is a top and
bottom layer of this brass that the primer is
sandwiched
in-between, you are left with a thickness of primer of around 0.017" for a
0.037" rim. If the rim is 0.041", the primer thickness becomes
0.021, or 24%
greater than in a 0.037" rim. This
variation in the amount of primer affects accuracy.
So,
what is the ideal rim thickness?
Excellent question. The answer sounds basic, but the ideal rim thickness is a
consistent rim thickness. You can obtain excellent groups with a rim
thickness of
0.038" or with a thickness of 0.040", but you will not have excellent
groups with a batch of shells that have both rim thicknesses. The
key is
consistency, and sorting is the only way to achieve this.
Although this unit is
primarily designed for use with a dial indicator,
you can also use a set of dial (or electronic) calipers.
Complete instructions are included.
This gauge can be used in
conjunction with the following common rimfire rifles (as well as many other
rimfire rifles):
Ruger 10/22, 1022, Marlin 795, Ruger
77/22, Ruger 96/22, Kimber model 82, Marlin model
782, remington 597, remington
vtr, browning a-bolt 22, chipmunk, plinkster, Mark II, Thompson center classic, Weatherby Mark XXII
Another Common Question:
Who is Raven Eye Custom?
From the owner:
“Raven Eye Custom products were
initially designed for use in high end custom target rifles.
Not until recently were these made
available as individual components. 1022
Armory is one
of the first retailers to begin offering our line of products.
The goal of Raven Eye Custom LLC is
to make affordable products that are of excellent quality.
Affordable excellence!
The takedown screws come with a lifetime guarantee
for the original purchaser. The product
will be replaced if it ever wears out or fails to be “excellent”. Simply return the screw to the
address posted on the packaging.
Suggested Retail Price =
$19.99. 1022Armory price = $14.99
Money order preferred. Email for other payment options.
Payment Methods:
Ships Using:
Money Orders,
