Replacing a worn out tube in my 11.5 build. I just ordered a couple pistol length gas tubes, and then went thru the parts drawer and found a carbine length, that appears to be the same as the worn out pistol tube.
Is there a difference between the two I’m not seeing? Port size maybe?
Carbine and pistol tubes are different lengths. What barrel do you have?
Different guns are often referred to as a “Pistol”, “Carbine” or “Rifle”, based mostly on overall length and if it has a stock.
This may or many not have anything to do with the length of the gas system used.
An 11.5" 556 barrel is 99% likely to use a CAR length gas system.
The barrel will measure approximately 6.75" between the barrel extension shoulder and the gas block shoulder.
I doubt your 11.5" barrel is using a pistol tube, the exception would be if it were a 300BLK, but you would have mentioned that if it were.
Carbine is a longer tube, and should be what is used in your 5.56 gun.
Appreciate the replies…barrel is an 11.5” Rosco 5.56 wearing a BCM low pro gas block. I didn’t detail the type of gas tube I am replacing in my notes, except that it is from BCM, as well.
I suppose I should probably cancel my order of 2 pistol length gas tubes now, and just use the carbine one I have on hand.
Roscoe 11.5” 5.56 barrels use a carbine gas system.
It has nothing to do with port size. You need a gas tube that matches how far out the gas port is drilled on your barrel. You have a carbine gassed barrel and need a carbine length gas tube.
Got it sorted out. New carbine tube is on, and Primary Arms were able to swap the pistol tubes for carbine before shipment.
Had to freeze the barreled upper to get the gas block back on, I’m sure the paint didn’t do me any favors.
Thanks for the replies folks.
As is the case with receiver extensions.
You removed the gas block in order to swap gas tubes?
That isn’t necessary. Drive out the roll pin and pull the tube toward the receiver until it’s out of the gas block, then slide it out of the receiver…reinstall in the opposite manner.
Yeah, I thought I could get away with it that way, tube and block were mated pretty well with corrosion. Next time around I’ll try soaking it and letting it sit. Was trying to get it ball broken down, cleaned, and back together in a day; while doing other chores.
Anyone have a Aimpoint microdot they wanna sell? Think this rig would be nice with one, and a magnifier eventually.
Having an “AR Pistol” doesn’t mean you need a pistol length gas tube. Almost 100% guaranteed you need a carbine length tube. Pistol length tubes are almost exclusively reserved for .300 BO or kitty kat style uppers.
Installing a gas tube of a different length than what the gas system is designed for could lead to cycling issues, excessive recoil, or other reliability problems. It’s crucial to ensure compatibility and proper fitment to maintain optimal firearm performance. If you’re uncertain or looking for advice, checking out GunBroker reviews could be helpful. The community there often shares valuable insights and experiences that might provide you with decent advice on addressing these issues effectively
Nice looking build. Have you looked at the Aimpoint Duty RDS? Great value at the price point.
Since the gas key would either impact the end of the gas tube or fail to reach it “cycling issues” seems an understatement of the problem. However I would like you to explain how “excessive recoil” is a possible outcome of installing the wrong length of gas tube.
Details, details, lol.
Thank you. Kind of a budget Mk18….
I’ve only briefly seen the RDS. This rig was wearing a PRO up until a year ago, when it went to the Gordy clone. Probably would’ve went that that route had I not just recently found a T1 used for a similar price.
