12-03-2018, 04:19 AM
The final machining and finishing. Some are better and more consistent at it than others. That being said just because some brands are expensive doesn't mean they are great at it either or won't have periodic issues.
An example would be BCM, their uppers pretty much require thermo-fitting of barrels, because of that they tend to shoot well provided a decent barrel is used. Their lowers on the other hand may or may not work with Gen 3 P-Mags, again because they tend to run towards the tighter end of tolerances.
An example would be BCM, their uppers pretty much require thermo-fitting of barrels, because of that they tend to shoot well provided a decent barrel is used. Their lowers on the other hand may or may not work with Gen 3 P-Mags, again because they tend to run towards the tighter end of tolerances.