all created equally?

[kpw]

Originally Posted by mjfletcher

as someone else mentioned, tolerances come into play. one manufacturer might allow 3 thousands of an inch (.003) in variation and another might allow 6 thousands of an inch (.006) and both would consider that acceptable tolerances. But if every piece that goes into one of the guns is off by the maximum tolerance, some plus some minus, It could result in a gun that jams heavily or has other problems.

Two guns coming off the line back to back can have pieces and parts that are closer and further from perfect but still within acceptable tolerance so pass all QC checks but result in one gun firing flawlessly and the other being an expensive paperweight.

ie: Firing pin is .006 inch shorter than spec, breech face is .006 inches thicker than spec, chamber is .006 inches shorter than spec. result is .012 inch less of the firing pin passes thru the breechface to strike the primer and the cartridge is .006 inches further forward than spec so the indentation in the primer is .018 inches shallower than the prototypes design. That MAY be enough to result in regular soft hits on the primer and failure to fire depending on the tolerances of other surrounding parts.

It's called tolerance stacking. Although all the parts might be within allowable tolerances, the end result isn't satisfactory. Getting a small lot machined or molded to a specific tolerance isn't hard. The problem starts when mass production begins and tolerances are often relaxed. The quality of your machinists or operators plays a big part in how tight your tolerances can be kept during production as well as your quality control standards.

[Qtrborecrazy]

Smokey240sx
Everyone is forgetting 1 problem with the whole prosses THE HUMAN PART. Every gun is put together by a HUMAN. You have some workers who have pride in their work and some that just show up for work. Same way with gun smiths,there are good ones and then there are excellent ones.

Qtrborecrazy

[PocketProtector]

In this day and age it is rare indeed to find machined parts "out of spec". The Manufacturing equipment of today is truly phenomenal.
Design and engineering are first and foremost when it comes to overall reliability of a product. Tolerance stacking etc. are all functions of the engineering process and "should" be thoroughly refined prior to a product reaching the production floor.
Occasionally a "run" may be defective for a variety of reasons, but a continuing defective product generally has engineering defects.

[kpw]

Originally Posted by PocketProtector

In this day and age it is rare indeed to find machined parts "out of spec". The Manufacturing equipment of today is truly phenomenal.
Design and engineering are first and foremost when it comes to overall reliability of a product. Tolerance stacking etc. are all functions of the engineering process and "should" be thoroughly refined prior to a product reaching the production floor.
Occasionally a "run" may be defective for a variety of reasons, but a continuing defective product generally has engineering defects.

Your absolutely correct. The Mazaks and Fadals we use at work are capable of keeping extremely tight tolerances. Our main problems, when they surface, are engineering and/or operator related. Basically, human error. That's where your QC standards come into play. Humans make mistakes, the ones that don't aren't doing anything. If you have a good engineering department, good machinists and a good QC program your going to see good products with lower instances of defects. If your lacking in any of the 3, your rate of defective products hitting the marketplace will skyrocket.