Loading for 2 rifles... only one set of dies?

[HarryN]

OK, I have a beginner question on this. The two competition rifles are reamed 0.005 inch different from each other - why ?

Precision machining can bring part to part tolerances a lot tighter than +/- 0.002. My brother used to work at a shop that held tolerances 10X smaller, but of course they also did the work in temperature controlled rooms.

There were also some interesting conversations about which oil film was on the part when it was measured and how long it was since the part had been "touched".

 

[Mikecr]

It's not a single machined parameter, but the sum of various dimensions, that lead to cartridges headspacing differently. Much depending on the barrel finishing approach/tools.
The action/bolt/lugs alone can affect HS in several ways, then you have the barrel shoulder to the recoil lug/action ring interface. The barrel is torqued which affects it.

A really good barrel finisher can match chambers, I've seen it with barrels chambered in pairs.
Your corner gunsmith using worn out reamers and a filthy process? That's another matter..

 

[AZShooter]

.005" is not quite 2X the thickness of the human hair. Doesn't take much to go right past a dimension. Remember the typical gunsmith is making one at a time, it isn't CNC machining.

The Kiff/Lambeth micrometer reamer holder helps but even it requires a delicate touch.

Micro-Adjustable Reamer Stop From PT&G « Daily Bulletin

 

[Dgd6mm]

Both barrels were chambered different years, different reamer, and different machines.

 

[Greyfox]

I have used Remington Milpec 700's for years in 308 and still own a few . I have found that I get the same .25-.5 MOA results using the same dyes(and loads). With my two hunting 6.5-284's I use the same shimmed body dyes and adjustable seating dyes. Bench rest rifles get their own dye set. I have helped a lot of friends and relatives learn how to reload on my bench but they have to buy their own dyes and if they dive in, ultimately get their own set up. Most all of them have. With all the reloading I do for my various rifles and the limited time to do it, I can't offer a reloading service and try to keep the least amount of variability at my reloading bench.