Forster 1.630 Go Gauge 308 cal.

Barring a chamber cast, I have taken the same case and fired it three times to determine chamber size. By this I mean firing a round then "partial sizing" (I don't have a neck sizer) Then taking that same case and loading and firing two more times, partial sizing each time. Then measuring. Partial sizing does not bump the shoulder.

As I said before, I am completely unsurprised that your "precision mike" did not zero on your new Go guage, but you have a "standard" now, so you can set your cases up any way you want, as far as shoulder bump. Esp. with the Redding set of shell holders in your toolbox.

A fellow who goes by the handle of "big ed p51" has posted on other forums that a round should fit the chamber like "a rat "dropping" in a violin case". If true, then we are in luck, because our 700 chambers are loose and sometimes a little out of round, about all we can do is set our head clearance correctly.
 
1100 Tac,
That's why I own a lathe and chamber reamers.
People scoff when I say the factory chambers are less than desirable in most cases...

Setting the barrel back, cutting a chamber that fits something that approximates SAAMI specifications so most of the stuff on the market will make fair to good rounds.

Getting a round chamber, one that centers on the bore without being at an angle to the bore, and getting reasonable headspace is fairly simple,
But for some reason, it escapes many 'Manufacturers'...
UNLESS you spend a pile of cash on a pass through the 'Custom Shop'.

Spend about $500 to $800 in the manufacturer custom shop,
They will set the barrel back, turn the chamber in a lathe, square up the reciever and get the optics mounts lined up with the bore/reciever.

Your local gun smith (actual trained gun smith, not the guy with a dril press & 12 hammers) can do it for $200 or so...

What kills me is guys spending hundreds on 'Match' triggers, high dollar optics, custom stocks & bedding, all the while ignoring lousy, misaligned chambers, misaligned barrels, misaligned optics, bolt lugs/bolt faces that don't line up or aren't square with the chamber...

It's priorities for me, basic mechanical functions first...
That includes making brass that fits the chamber.
 
1100 tac
I use to neck size & partial size. Didn't check the length, even after 24 reloads without a hard bolt lift or close. The stock Remington LTR I never checked the headspace, had plenty free bore though, shot very accurate. When I changed the barrel to a M24 5R Rock Creek with a match tactical chamber did I bother with headspace , jam , jump and all the gauges and fun stuff that comes along with it. Now I only full size with .0015 space between case head & bolt face.
 
I'm with Mr. Guffey,
I start at 'Zero'. No substitute for 'Zero' measuring.

Once a case fits the chamber, it's the 'Standard' to work from.
Measure it from a 'Zero' point (head stamp end) and reproduce it.
Make your changes gauging from the head stamp 'Zero' point.

Most people work on this or that, kind of randomly, not realizing the interaction on what follows...

I tell people to start at the head stamp, work up to 'Datum' point (or Datum Line, which ever you prefer),
Then, and only then, work the top of the shoulder/bottle neck, and the neck.

Most people ONLY check for length, rarely checking for headspace at the Datum point, so the brass fits the chamber correctly,
Then working from datum point for neck size & length.

I *Try* to work the brass as little as possible in single firearm produced brass,
Modifying dies to 'Fit' a specific rifle.
By NOT overworking the brass, it doesn't harden as much,
Having dies modified specific to the chamber, the brass body doesn't bloat/blow out as far, and you don't have to push it way back in.
Less work hardening, less annealing, longer life for your brass, and more accurate brass.

That's my way of doing things,
Not a ton of gauges (with relative 'zero' potential), no two gauges agreeing on anything...

Brass that fits the chamber, bump (not over compress) the shoulder/case just enough to fit the chamber & restore headspace, compress neck just enough to hold bullet just enough to retain your bullet correctly, and leave the rest alone...

For me, this takes TWO dies, one to decap, restore chamber clearance & headspace,
The second sizes the neck WITHOUT moving shoulder/datum point.
This makes the dies specific to the chamber of the ONE particular rifle.
Trim to length and off to the races...
 
I feel comfortable now using my rifle chamber as a guide when sizing. After check all my gauges against each other, using the measurement off the Go Gauge of 1.630 I can get a headspace measurement and double & triple check using the PM & dial caliper with the comparator. I take time in prepping my brass ( 30 cases ) I feel its the most critical area for accurate reloads. Now I can put a number on my headspace ( 1.6315 ) for what it's worth. Buying all the different gauges , had to learn the hard way. I find the Precision Mic. from RCBS the easiest to use. Sunday's my range day, looking forward to shooting & starting all over again. Till the next time, Be Safe out there. Chris
 
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