Maximum gas port size?

[Dvando20]

What is the max you can go with opening up the gas port on an 18" SPR TBox barrel in .223Wylde without asking for catastrophy? It's already at the max-spec .098" with an SLR adjustable block, but it's still short stroking with the block all the way open. Tried different springs, buffers, blocks, etc. Was told to open up the port more, then tune it down with the SLR block. I was thinking a max of .140" (5/64) but unsure. I have opened up undersized ports before to fix issues, but never gone above spec. Just want to know the maximum I can go with this and still be in the safe zone. Thanks.

 

[Constructor]

Sounds like something else is causing the short stroking. Make sure you do not have gas leaks between the gas block and barrel and between the gas tube and gas block. A .093 port should work with a standard spring and buffer and M193/855 if everything else in the build is correct, been doing it for 30 something years.

 

[Dvando20]

Sounds like something else is causing the short stroking. Make sure you do not have gas leaks between the gas block and barrel and between the gas tube and gas block. A .093 port should work with a standard spring and buffer and M193/855 if everything else in the build is correct, been doing it for 30 something years.

Yeah, this thing has been a problem child since its existance. None of my other rifles have this problem

 

[drcrk0525]

My buddies BA 18” 223 Wylde barrel is doing the exact same thing. We’ve swapped every part except for the barrel. We ended up opening it up to .104. Going to try it out this week and see if it helped.

 

[Fret]

Is it a rifle length gas system? If you reload, try slower burning ball powders like CFE 223 or BL-C2 which would let the pressure stay higher for a longer period to help cycling than something like AR Comp.

 

[KZP]

Have you checked that your gas tube is long enough? I remember seeing a photo in another thread where someone had issues and their tube was slightly shorter than required based on the barrel port location.

 

[drcrk0525]

Buddy shot his rifle today and fixed the issue. Now runs 223 fine and throws the brass about twice as far.

 

[bfoosh006]

Have you thoroughly checked the gas key for leaks ?

.140" is damned big.

And you are positive ( no offense intended ) the gas port and gas block are properly aligned ?

 

[msgriff]

The internal diameter of a standard gas tube is around 0.120". Not much to be gained by going larger. Use numbered drill bits, not fractional. Going up more than necessary can cause other problems, even with a AGB. The 0.104" mentioned above seems reasonable.

 

[greg1147]

Have you thoroughly checked the gas key for leaks ?

.140" is damned big.

And you are positive ( no offense intended ) the gas port and gas block are properly aligned ?

Usually the gas block is about .020"-.025" off the shoulder.

 

[mtrmn]

Have you checked that your gas tube is long enough? I remember seeing a photo in another thread where someone had issues and their tube was slightly shorter than required based on the barrel port location.

Gas tube must end at the halfway point of the cam pin cutout. Make sure the gas key on the bolt carrier is tight and the screws are staked properly. I had one that was staked apparently before the screws were tightened.

 

[longshot2000]

I agree with a number of posts here. Something is happening that is not port size related, I think. Gus tube? There are some Chinese made tubes flooding market. We use Remcon mostly. Other sources like Daniel Defense, even PSA are reliable. Also, KAK makes a great tool to align the gas port to dimple the bottom, so you know you are at 6:00. Also, health ck of the gas key and carrier.

 

[308guru]

I had a similar issue. My 300blk wouldn’t lock back on last round and sometimes would not go into battery.

Tried different buffers and springs, no go. I was thinking of enlarging the gas port but first tried a bcg from a different rifle and it worked perfectly I knew the original one felt weird and kind of notchy/sticky while unlocking but didn’t think much of it.

I called the manufacturer of the bcg (Toolcraft) and they had me send it in. A replacement arrived promptly and had worked fine ever since.

Try swapping your bcg or any other parts first to see if you can narrow it down to one.

 

[Dvando20]

My buddies BA 18” 223 Wylde barrel is doing the exact same thing. We’ve swapped every part except for the barrel. We ended up opening it up to .104. Going to try it out this week and see if it helped.

It fixed my issue opening it up but not happy that it required that being a TBox and now I have gas bleed-off coming out around the block. I have a brand new BA 18" SPR in .223Wylde sitting at home with the factory gb that came drilled for a pin for proper alignment. Going to put that on and see if it does the same thing.

 

[Dvando20]

Thanks for all the good advice for things I would have not thought to look for. I did drill the port out and it did fix the problem, but just as a learning experience I am going to look at all these other options and see if the problem was staring me in the face the whole time. Thanks again everybody.