Sinclair Seating Depth Tool Question

[AznTactical]

For those that's using Sinclair Seating Depth Tool I have a question. Has it ever given you false reading of where your lands are?

I've been using Sinclair's seating tool to measure where the lands are to help me with my seating depth for my handloads for 8+ years but I am stumped on the caliber and the components used below.

7 PRC, Peterson brass with ELDM 7mm 180's and ELDX 175's ONLY. Using this Sinclair set, it is putting my lands at 2.393" BTO or 3.197" COL. Recommended COL per Hornady's reloading book is 3.32" which equates to 2.516" BTO. Now here's the kicker......I loaded a few handloads to 3.32" COL and was able to close the bolt and fire the rounds successfully. I shouldn't be able to close the bolt.......

I have no issues finding the lands with the same tool when I use Berger 7mm 180's. I hit the lands at BTO 2.579" (3.403" COL). For example if I am loading 0.030" off the lands I would load the Bergers to 2.549" BTO (3.373" COL).

Any ideas on a short BTO?

Currently I am trying the loctite method. apply loctite to inside neck, loaded round to 3.32" COL. feed cartridge into chamber, close bolt. Come back tomorrow or Monday to check how much it shifted.

 

[Rocketmandb]

Currently I am trying the loctite method. apply loctite to inside neck, loaded round to 3.32" COL. feed cartridge into chamber, close bolt. Come back tomorrow or Monday to check how much it shifted.

I started doing this. At first, I was reticent to put an adhesive in my chamber, but a friend swears by this method, so I decided to give it a try.

I measured using the Hornady gauge/modified case (multiple times) and then did the Loctite thing. The Hornady gauge delivered a measurement about 8 thousandths shorter than the Loctite method.

I'm kind of sold on it now. You just have to be careful to keep all the Loctite in the neck and carefully wipe the outside prior to putting it in the chamber.