
Originally Posted by
rsilvers
A cam pin is specced to have a certain diameter, +- 0.00025 (this is about 1/10 as thick as a hair). Whoever decided on that, decided it was needed for some reason. Too large and it may bind. Too small, and it may be sloppy. The end result may be excessive wear and/or unreliable function. When it was time for us to select cam pins, we compared many - and the Colt ones were in spec. The others - not so much. Some were not the right hardness. Some where over-sized. Some were missing the required dry-film lube. The dry film lube is a whole -nother ball of wax because it has its own tolerance for application. So there is tolerance stack, which makes it harder to get into the +- 0.00025 range. Our solution was to make them to a drawing rather than buy them by name from an AR parts vendor. This means, we can check them to the drawing and reject the ones outside the spec. If a company were to just order 'cam pins' then they would have a hard time rejecting any outside the +- 0.00025 range because they have no drawing they can point to as to why they are rejecting it. We also then did not use regular dry-film lube but hardened electroless nickel. This coating has the lubricity but does not wear as much, and can be applied very evenly, leading to fewer parts to reject. So yes, we stick to the mil spec in general, but will deviate when improvements can be made - such as this coating (or for example nitrided barrels rather than chrome lined).
So... are your cam pins in spec dimensionally? There are plenty out there which are not.
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