Rimfire rim thickness measuring gauge 22LR 17Mach2
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FFL is not required
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8/8/2017 10:51 AM
Item 676744839
Location Arvada, CO 80002-4942
1st Class$2.85
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No international shipments
Payment Certified Funds, PayPal, See Item Description
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The seller of this item assumes all responsibility for this listing. You must contact the seller to resolve any questions or concerns before placing a bid. Payment must be made using U.S. dollars ($) unless otherwise stated in the listing. Firearms may only be shipped to a licensed dealer (FFL Holder). Some listed items may not be legal in every state. Complete your purchase within the law.



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:


1          Rimfire rim thickness measuring gauge for 22LR, 22 short and 17 Mach 2

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 through many online vendors

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 22LR and 17 Mach 2 ammunition, and will not work with 22 Mag (22WMR) or

17HMR.  There is another gauge designed to specifically measure these rounds.  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 


Shipping will be via USPS.  Shipping cost = $2.85.  Additional like items ship free!



Postal sorting equipment damages hard goods placed in standard envelopes.  OURS WILL ARRIVE SAFELY.



Just purchase using "Buy It Now" and then request an invoice for the savings.







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