My apologies if this was discussed before (couldn't find it in a search).

I have a 20" barrel that I'm thinking of chopping to either 18" or 16" (the latter would be the look of a disapator), and wondered if there were any technical issues I needed to know of beforehand.  It seems that when we've talked about SBR reliability, the issue is the lack of barrel forward of the gas port, and therefore the gas port sometimes has to be opened up to prevent shortstroking.  Will a 16" or 18" barrel with a rifle length gas system have a similar issue?

Thanks very much.

Yes, you will have to open the gas port. Not that big of a deal.

Thanks.

Does anyone know what the port size will need to be?

surprised you couldn't find anything in a search, the question gets asked about two or three times a week... there are two answers and it depends on who you are, what you expect, what you call reliable and how important it is to you.

If you keep the weapon clean, avoid really crappy weather, transport the rifle in a padded case form you house to a range once a week and consider six or eight magazines without any failures stellar performance... then you will have no problem with it.

If you honeslty have to decide between cleaning your weapon and sleep, have no choice on the weather or location you are in, would fold the gun case up and sit on it if you had one and you are shooting 2,000 rounds a week... no, you probably will not be happy with it.

In 1986 we cut back some rifles to 16" for testing, they were determined to be unrealiable as a *service rifle*, but again, they were abused and it was the performance in cold weather that really killed them. Now today we have hotter ammo and all of that, but I assure you that the dwell time is considered far to short and unreliable for a rifle that will be used in the defense of human life.

Thanks for all the responses.

I've got several ARs, and a 20" barreled upper that I'm not using.  I was considering this project for really just having something different, since I have the M4 lookalike, a midlength, a midlength RECCE style, a 9mm carbine, a AR10 carbine, a A1 clone, an A2 clone, an A4 clone, a SPR/SAMR like rifle, and two other carbines, but nothing that looked like or was a dissapator.  I like the look of the SLR-15 Commander rifle that Sully is making and thought I'd use the upper for the project.

I only shoot Q3131a, Fed Am Eagle, BH Match, XM193, and WWB 62 grain FMJ.  I don't like Wolf in my ARs.

Seeing the responses, I may just sell the upper and get a dissaptor or Sully rifle instead.

Quoted: Thanks for all the responses. I've got several ARs, and a 20" barreled upper that I'm not using.  I was considering this project for really just having something different, since I have the M4 lookalike, a midlength, a midlength RECCE style, a 9mm carbine, a AR10 carbine, a A1 clone, an A2 clone, an A4 clone, a SPR/SAMR like rifle, and two other carbines, but nothing that looked like or was a dissapator.  I like the look of the SLR-15 Commander rifle that Sully is making and thought I'd use the upper for the project. I only shoot Q3131a, Fed Am Eagle, BH Match, XM193, and WWB 62 grain FMJ.  I don't like Wolf in my ARs. Seeing the responses, I may just sell the upper and get a dissaptor or Sully rifle instead.

Mid-length gas system dissy is a nice setup really, I have one that is at the top of my *favorites* list, mostly just for being so simple... regular old iron sights, plastic handguards, light, handy and simple...