Seating depth - once fired Nosler v Hornady mod case?

[Freedomaintfree]

I got the Hornady OAL gauge and a Hornady modified case to determine seating depth on my 7mm Rem Mag.

However, I am using Nosler brass that is once fired to load the ammo.

I understand there can be some difference in the measurements of seating depth with two different cases. Without a lathe to make my own modified case how can I use the Hornady kit to get a good measurement of seating depth on once fired brass?

 

[Mainer]

Making a modified case does not require a high degree of precision. You can make one without a lathe. I used a drill press, but believe it can be done with a hand drill.

 

[Mainer]

I also did not have confidence in the Hornady modified case. It seems to me that the OAL should be measured from the bolt face to a datum point on the chamber shoulder and if the modified case does not match that for your chamber you are not getting good measurements.

 

[Freedomaintfree]

Is the cleaning rod /stopper method more accurate of a measurement?

 

[_Raining]

Just measure the headspace difference between the Hornady case and your Nosler brass and add the difference, IDK why everyone thinks they need to make a modified case from their fireformed brass.

 

[Freedomaintfree]

That’s what I originally thought but trying to make sense of all the YouTube videos I have watched and I wasn’t sure if that would give me an accurate measurement... I am very new to this

 

[_Raining]

There is also this:

 

[Pvt.Donut]

I use the Sinclair seating depth gauge so I can use my fired brass.