Adapting Cases for the Hornady “OAL Gauge”

by
posted on May 19, 2015
hornady_oal_gauge.jpg

The Key Handloading Accessory
A key step of careful handloading is to determine the ideal overall cartridge length (OAL) for your particular load. Not only can seating the bullet close to the lands produce greater accuracy, but it can effectively increase the case capacity of your cartridge, which allows for lower operating pressure, all other things being equal. There are several tools on the market for determining OAL, but the Hornady tool is my personal favorite.

How It Works
The Hornady tool (mine is old enough that it was made by Stoney Point) uses modified cartridge cases that thread onto an aluminum tube. You place your selected bullet into the case, slide the cartridge into the rifle’s chamber and push forward on a rod that runs through the tube’s interior. This rod pushes the bullet forward until it contacts the lands of the rifling, at which point you lock the rod into position with a small knob. Once you retract the tool, you can measure the length of the cartridge an immediately determine in the OAL to the lands with that particular bulletit is simple and brilliant.

The Modified Case
Hornady offers a pile of cases in various cartridges (most are $6 or $7) and, if one is not available, they will modify your case for use with the tool for $15, shipping included. But if you have a pile of tools lying around like we do, why pay someone to do what you can do yourself?

Adapting Your Own
I set out to adapt my own cases for use with the OAL tool. The case needs to be deprimed, drilled-out and tapped to the correct thread pattern. To do this yourself, you’ll need a way to hold the case while you drill and tap it, a way to deprime the case and the correct drill bit and tap.

I began with a fired case for two reasons: First, the bullet needs to be able to slide freely into and out of the case neck; secondly, I wanted the case to fit perfectly in my chamber so the measurements would be as precise as possible. I deprimed the case using a Lee depriming die which pops the primer without disturbing the case dimensions. I then placed the case into the 3-jaw chuck of my lathe, applying enough tension to hold the case without crushing it.

undefined

Using a 9/32 drill bit at low RPM, I drilled the back of the case to the proper size to fit the OAL tool. 

undefined

It is crucial that the hole be drilled perfectly straight, and that the threads are aligned with the bore of the hole. In order to accomplish this, I used my lathe’s “center” to position the tap wrench.

undefined

Using tapping oil and cutting slowly, the 5/16-36” threads were cut on the case. 

undefined

 

Once the threads were cut, the modified case threaded perfectly onto the tool. 

undefined

Latest

LEDE Henry Handguard On White
LEDE Henry Handguard On White

XS Sights Introduces Handguard for Henry Lever-Action Rifles

Designed for modern lever-action enthusiast who want to upgrade their Henry rifle, this highly customizable handguard is equipped with six M-LOK slots on each side and seven on the bottom to accommodate a wide array of accessories.

Montana FWP Announces 2025 Migratory Bird Stamp

A trio of tundra swans winging their way through a gray sky in the shadows of Rocky Mountain peaks is captured brilliantly in the 2025 Montana Migratory Bird Stamp.

Tested: EAA Witness2311 10mm Auto Hunter Pistol

This 2011 double-stack pistol is available with a six-inch barrel and an optics-ready slide for less than you might expect.

New for 2025: Escort Shotguns WS Youth 20-Gauge Shotgun

Youth shotguns are often the first introduction to hunting for many individuals, and Escort Shotguns is looking to help continue that tradition with its WS Youth shotgun.

Busting the Roost Myth: Why You Shouldn't Tree Talk to Toms

Should you call to a roosted tom? Mike Roux fills his readers in on why this popular strategy may be the reason they don't fill all their tags this spring.

Pennsylvania Antlered Deer Harvest Best in Four Decades

Pennsylvania hunters harvested about 11-percent more deer in the 2024-25 hunting seasons than they did the year before, according to Pennsylvania Game Commission estimates released late last month.

Interests



Get the best of American Hunter delivered to your inbox.