Gas system lengths.

[GunnyUSMC]

Gunny:

Permission to download your photo and share it with my SF nephew?

Geno

Go ahead.

 

[Coal Dragger]

I would suggest finding out from the manufacturer what the gas port diameter is on the barrel you’re considering.

It seems far too many manufacturers are drilling enormous ports these days so the AR’s they sell to Bubba will run on the underpowered filthy swill ammo from Eastern Europe. When you then turn around and feed the same rifle that will cycle Wolf or other low powered garbage M855 or MK262 5.56 NATO it will be ejecting brass to the 1:30-2:00, chewing the rim up on the case, and recoiling noticeably harder.

A rifle or carbine that is really properly made to run NATO spec loads will probably not play nice with remanufactured powder puff 55gr .223 or similarly loaded but filthy Eastern European equivalents. I will choose the gun made to run the NATO loads every time, because I don’t feed nice guns crap ammo.

 

[Demi-human]

Agreed. I only use handloads. Cleanliness is a happy byproduct.

 

[Glockula]

I have found that shorter gas systems develop pressure more quickly when testing hand loads. I can get by with less gun powder cycling the bolt in my pistol gassed 300 blk than my carbine.

With the pistol gas system upper end loads have extremely flat primers and show pressure signs when the carbine doesn't.

 

[Chuck R.]

Unless you are going beyond 24 inches for the barrel, I wouldn't recommend going with the +2 in any case.

Depending on the distances you plan to attempt with this prairie dog rifle, you would probably be well served with a 20 inch barrel and save yourself some weight.

The velocity gains of 223 drop off pretty quickly after 20" and really quickly after 22".


If you are already looking at JP for barrels, if you paired it with one of their muzzle brakes and used their LMOS carrier and an adjustable gas block, you will be able to watch your hits on varmints through your scope.


Necessary for proper function? No.

Significantly improved recoil characteristics? Yes.

For my last build I used: 16" LW barrel, mid-length gas, adjustable gas-block and a low mass BCG and LW buffer.

It is the "softest" shooting AR I have, very little muzzle rise. It also runs cleaner than my other ARs as only enough gas to run is passed through to the BCG. My next build will be similar.