Wilson vs Lyman - Case Length/Headspace Gauge Question

[Ahsan Ahmed]

I do not know enough yet to draw conclusions on my own - hence the question ....

Is it normal that a case guage cut to the same (SAAMI) spec exhibit some difference between two manufacturer products?

The following are two 6.5x55 (1F) brass:

- Both cases (same brand) are from the same lot of brass that had been fired in the same rifle (not mine).
- Neither case has been resized.
- Both cases fit the Wilson gauge properly but not the Lyman.

Given the Wilson instance, out of curiosity, I tested to see whether the brass might fit the chambers of my rifles - obviously, that was a No Go.

 

[eschafer]

That's the problem with case gauges, they tell you NOTHING about what your chambers' require, as far as brass sizing... Google (Larry Willis / Innovative Technologies) and have a close look at his "Digital Headspace Gauge". It's really not a "headspace gauge" but rather a digital comparator.. It works well, but, you need to verify your chambers' lengths FIRST with a sacrificial case from each chamber (keep that one case from each chamber in a safe spot and use it for comparison when again sizing for that cartridge) .. It functions for all bottle-neck cartridges without the need for individual gauges for each cartridge. It also can be used for COAL measurements as it can be configured to measure on the bullet ogive rather than the brass shoulder... No, not affiliated with Innovative, but I do own one of his Comparators, and it's made reloading so much easier for me. If you get one, place it up high (near neck height) as having it up higher makes it so much easier to read and use... If you're already an Innovative "hater", as so many on reloading forums are, then merely disregard entire post...

 

[Ahsan Ahmed]

Thanks, will take a look at the tool.

 

[bigedp51]

The Wilson case gauges are larger in diameter than your Lyman gauge. And because the Lyman gauge is smaller in diameter a "FIRED" case will not drop all the way into the gauge.

Below another example of variations in case gauge inside diameter. Below is a "FIRED Lake City 7.62/.308 case in a Dillon case gauge. I can't remember if a ding in the case rim or case diameter kept the case from falling all the way into the Dillon gauge.

Below the same "FIRED" Lake City case in a JP Enterprise case gauge. This gauge is closer to the minimum SAAMI case diameter and the fired unresized case sticks out further in this gauge.

Bottom line the majority of case gauges are at the maximum SAAMI chamber diameter. And these type of gauges will only give you a "ball park" idea of the case shoulder location. Meaning you need a gauge that can measure the fired case shoulder location, so you can adjust the die for the proper amount of shoulder bump.

Below I'm using a Hornady cartridge case headspace gauge to measure a "FIRED" Lake City 5.56 shoulder location or case headspace. I then set my die up the die for .003 shoulder bump for my AR15.

I use my JP Enterprise case gauges to check the case body diameter after sizing and again after bullet seating. If the case fits in the JP Enterprise gauge it will chamber in any rifle.

 

[Ahsan Ahmed]

Much appreciated the detailed insight. Greatly enhanced my understanding of the subject matter.

 

[Biologist]

If I am not mistaken, Wilson makes their case gauge diameter quite wide on purpose in order to accommodate the spectrum of fire-formed shapes from a wide variety of manufacturers in the same caliber. I think (IIRC) they state in their literature somewhere that their case gauge is meant only for checking headspace and overall case length, but it is not made to check chamber fit or case web expansion.

 

[bigedp51]

If I am not mistaken, Wilson makes their case gauge diameter quite wide on purpose in order to accommodate the spectrum of fire-formed shapes from a wide variety of manufacturers in the same caliber. I think (IIRC) they state in their literature somewhere that their case gauge is meant only for checking headspace and overall case length, but it is not made to check chamber fit or case web expansion.

Biologist I'm going to mark you down as having a very good memory.

https://lewilson.com/case-gage

The "Wilson Case Gage" A one piece gage that will check overall length and indicate min/max case length
Measures min/max Headspace. Does not measure body diameters
This gage is intended to be used with fired cases to determine a basis for full length sizing and case trimming