Thread: Hornady OAL Gauge

Hi
I finally got one of these units and started measuring my loads, to my surprise all of my goto loads are longer than the length suggested by the gauge as the OAL, touching the lands. I used to use a slightly sized case and just load it into the chamber and close the bolt, but I am now thinking that even with 20 thou less it is still jammed into the lands. I had a 7-08 blow a primer last month and thought it was soft brass, but now I'm thinking pressure caused by too long OAL. In all my load developement I mic the web of the cases for excessive stretch from pressure and haven't noticed any spikes. Does anyone have any thoughts on the Hornady OAL gauge and how accurate it is?
If my gauge is correct then it is a warning for others to be careful in determining OAL for their rifles. Interested in thoughts of the fonts of knowledge here

Regards
7mm

Hornady OAL gauges are OK but only if you use a case fired in your own rifle as the testing case. Easier said than done but I have a mate with the correct tap to tap out the primer pockets once drilled so therefore the cases I use for measurement have all been fired in each of my rifle chambers - one case for each rifle. If you don't use your own cases I have seen errors up to 5 thou using the Hornady cases. You can check by measuring to the datum point of the shoulder of you own fired case (Hornady have gauges for this) and then the Hornady case and doing the maths from there, and then use the Hornady case with the difference factored in. Also when doing the projectile pushed up to the land stage do the measurement several times and average the result. You should however be within a few thou of each measurement. If not the things that will give you very differing measurements are worn/fire cracked lands or a carbon ring (carefully clean the throat area with JB or autosol and redo the measurements). Hornady OAL gauge is OK but obviously only a starting point for seating depth and a check to make sure you aren't into the lands and having the risk of a high pressure spike. Looks like you had taken that into account at any rate.

Hi Zimmer
Thanks for those thoughts, I will check the Hornady cases against my own and make adjustments, good idea.
Many thanks
Regards
7mm