AR15 gas systems and parts question

[Alex45ACP]

Other than the barrel, gas tube, and handguards, is there any difference in parts between an AR15 with a 16" barrel and midlength gas system, and an AR15 with a 16" barrel and carbine length gas system?

Could you switch a 16" barrel midlength gas system upper to a 16" or 14.5" barrel carbine gas system upper simply by changing those parts?

 

[Bartholomew Roberts]

No, no difference and yes, they can be changed

 

[benEzra]

The only difference I see other than the barrel, gas tube, and handguards is that the extractor spring and insert *may* be different, depending on the rifles in question. The consensus over on M4carbine.net seems to be that the heavy-duty extractor spring and black insert are required for reliable operation of a carbine-length gas system, but aren't necessary on a midlength because extraction is less violent. As a result, you might see different springs/inserts on a top-tier carbine extractor vs. a new-in-the-box midlength extractor.

I doubt it would be a problem to run the stiffer carbine-style spring and insert on a middy, though, so you wouldn't necessarily have to change them.