Originally Posted by
ABNAK
Okay, but the pressure (where ever it originates or is dispersed from) is the issue, and ports control it to a large degree, i.e. whether the round is loaded hotter or the amount of pressure coming from the port is the issue. That tighter or looser regulation of pressure is what can cause accelerated wear or malfunction issues (like you said spring strength, buffer weight, adjustable gas blocks, and special BCG's address this one way or the other).
Example: the Hodge Defense barrel has an ever-so-slightly smaller gas port than most 5.56 weapons, and is a mid-length to boot. It was made that way to handle the relatively hot M855A1 on a regular basis. Having personally tested some high-end 5.56 pressure rounds---M855A1, Mk318, and Mk262---with an LMT Enhanced BCG I had about a 20% failure to lock back on the last round. That was the only "malfunction", otherwise it fired/fed/extracted fine. I switched to a standard BCG and it locked back every time. I'll bet my paycheck that if I had tried most .223, especially the garbage steel-cased foreign .223, failures to lock back would have been the least of my issues. So in the case of this particular barrel the port size was regulated to "tame" a specific round by limiting the amount of pressure delivered to the action.
You are one of our engineering whiz-kids so debating this kind of science is waaayyy out of my lane. I think we're talking semantics here though. Pressure and how it's delivered (regulated by the variables we mentioned) does indeed have an effect on wear of parts, specifically the bolt. A rifle set up to shoot .223 should have no issues cycling 5.56. However, a steady diet of 5.56 will likely increase wear on parts over time if all the variables were left unchanged, correct?