As I slowly but surely make my way through the load development process I find myself agonizing over accuracy and precision, just my nature, but I also find myself wondering am I over analysing too much? And am I expecting too much from the equipment I am using?
When it comes to seating depths what is the allowable tolerance on the measured COAL?
Using my lock n load gauge, comparator set and Hornady digital caliper I measured the chamber COAL in my 7mm Rem Mag at 3.736" with a 7mm Berger 180gr VLD hunting bullets. I did this 3 times and got the same number each time. Then using a standard RCBS seating die I made up a dummy round progressively seating the bullet deeper and measuring until I reached 3.716" or .020" off the lands which is where I want to start for my load development. I then set the jam nut and began seating bullets into my prepped and charged cases.
As I measured each loaded round I found that I was averaging 3.715" +/- .001" not the 3.716" I was after. Now I understand this could be the accuracy tolerance of the caliper or the repeatability of the die and seating stem, which is a whole nother issue as I am using the standard stem with the VLD bullet but I didn't want to go through the whole process of ordering a custom stem for these dies and VLD bullets when I can already see I will soon upgrade these for a set of Redding dies. Plus I am only seeing a very faint ring approximately .260" off the meplat.
So is this an acceptable tolerance for seating depth and would you still classify this as .020" off the lands? These first rounds will be used for a ladder test so I am not too worried about this right now but the next step for me is tuning seating depth where I may be adjusting it as little as .002" and with a +/- tolerance of .001" this may be a bit if a problem.
Just looking for guidance and experience!
Thank You,
Jacob
Sent from my SAMSUNG-SM-G935A using Tapatalk
When it comes to seating depths what is the allowable tolerance on the measured COAL?
Using my lock n load gauge, comparator set and Hornady digital caliper I measured the chamber COAL in my 7mm Rem Mag at 3.736" with a 7mm Berger 180gr VLD hunting bullets. I did this 3 times and got the same number each time. Then using a standard RCBS seating die I made up a dummy round progressively seating the bullet deeper and measuring until I reached 3.716" or .020" off the lands which is where I want to start for my load development. I then set the jam nut and began seating bullets into my prepped and charged cases.
As I measured each loaded round I found that I was averaging 3.715" +/- .001" not the 3.716" I was after. Now I understand this could be the accuracy tolerance of the caliper or the repeatability of the die and seating stem, which is a whole nother issue as I am using the standard stem with the VLD bullet but I didn't want to go through the whole process of ordering a custom stem for these dies and VLD bullets when I can already see I will soon upgrade these for a set of Redding dies. Plus I am only seeing a very faint ring approximately .260" off the meplat.
So is this an acceptable tolerance for seating depth and would you still classify this as .020" off the lands? These first rounds will be used for a ladder test so I am not too worried about this right now but the next step for me is tuning seating depth where I may be adjusting it as little as .002" and with a +/- tolerance of .001" this may be a bit if a problem.
Just looking for guidance and experience!
Thank You,
Jacob
Sent from my SAMSUNG-SM-G935A using Tapatalk
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