New guy with a question

**Rocknoggin** · 06-17-19, 10:13

Hi, just joined the forum and I have a question. A friend recently bought a Colt M4 Carbine and let me try it, and now I want one. It was the first time I'd shot any type of AR. Last 'black rifle' I shot was an M16A2 when I was in the Army (got out 25 years ago). I like my friend's M4, it functions flawlessly. But the M4 Trooper caught my eye. I started doing some digging and I'm running into lots of terminology I've never heard of. What's the difference between a mid-length gas system and carbine gassed? And which does these two have? I heard someone say mid-length is better but I don't know why.

**556BlackRifle** · 06-17-19, 10:32

Welcome to M4C. If you do a forum search you can find a lot of good info on questions that have been asked and answered over the years. This thread should get you started. Good luck.

https://www.m4carbine.net/showthread...carbine-length

**556BlackRifle** · 06-17-19, 10:32

Double Tap.

**TomMcC** · 06-17-19, 10:37

Believe they both have a carbine gas system. The difference is where the gas port/gas block is placed. So on the carbine gas system the distance between the bolt carrier and the gas port is 7", on the mid 9". One of the ideas for a mid was to soften the felt recoil a bit.

**Rocknoggin** · 06-17-19, 10:48

Originally Posted by TomMcC

One of the ideas for a mid was to soften the felt recoil a bit.

That's it? Makes no difference to reliability?

**TomMcC** · 06-17-19, 10:58

Originally Posted by Rocknoggin

That's it? Makes no difference to reliability?

I don't really remember all the technical reasons for it. Someone with more knowledge will have to answer that. An increase in reliability could be one reason, but in day to day use that's more theoretical IMO.

**Eurodriver** · 06-17-19, 11:15

I started going to church.

**MistWolf** · 06-17-19, 12:31

Originally Posted by Rocknoggin

That's it? Makes no difference to reliability?

The middy gas system done correctly is slightly more reliable than the carbine gas system when used in conjunction with 14.5 & 16 inch barrels. The middy taps gas from the barrel a couple of inches further from the chamber where the pressure is a bit lower. The middy is a little more forgiving. But there it's nothing wrong with the carbine gas system when done right.

I've shot Colts with 16" barrels with carbine length gas systems and they work fine, better than some of the other brand ARs with middy gas systems. With the carbine gas system, I prefer the 14.5 inch barrel over the 16 inch barrel, but to be honest, that's to satisfy my CDO more than for any reliability gains. Any of the Colt carbine configurations, 6920, Trooper, CCU or lightweight, will serve you just fine. Pick what you like and get to shooting!