Might need an adjustable gas block

KnotRight

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Problems at the range today.

I changed out a barrel on an AR-pistol (223) to be able to mount a can. Before the change it was an 8" barrel and had to replace it with a 8.5" to be able to get the can on. Before the change I had no problem with the gun cycling. Now it is short stroking without the can and running great with the can. It is a pistol length tube and the diameter is 0.750. I am using the pistol length spring and think that I have the right buffer.

Looking for suggestions on an adjustable gas block.
 
SLR Sentry is what I run on several of mine.
 
Do I need to make sure it is larger than 0.750 when open all the way?
I don’t understand the question.

.750 is the diameter of the barrel...nothing to do with the gas port. 3/4” would be a massive hole. :D

The port in the gas block will be bigger than the one in the barrel. You’ll close it as needed.
 
I just pulled the the gas block off the gun and the carbon build-up around the barrel port was a complete circle with the port in the middle. Cleaned the port and realigned the gas tube as good as my eyes could see. Not sure when I can make it back to the range to test it. If this does not work, I am going to have to see what size port I have on the barrel. Here is a picture of the port.
Port.jpg
 
One more thought. I am shooting some reloads from 2016 using IMR3031 @ 3000 ft/sec. If the gun was working before the can, I might have been shooting a different powder. Do you think that 3031 built up enough pressure using a pistol length gas tube?
 
If your gun is under gassed, an adjustable gas block won’t help. You’d need a bigger gas port. AGB can only choke gas, it can not add gas.
I’d also check that the spring is a normal carbine spring, and the buffer is a standard carbine buffer. If these are heavier than standard, it could cause your issue as well.

edit: unsure on reloads. I’d test with factory.
 
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Thing is .. how likely is it you'll shoot it without the can attached? if it were mine id shoot suppressed and wouldnt look back.
 
Thing is .. how likely is it you'll shoot it without the can attached? if it were mine id shoot suppressed and wouldnt look back.

Catfish I agree!!!
What I was thinking is that the case the gun is in is too short to keep the suppressor mounted. If I had to use it on a hurry, it is a single shot (no I do not live in CA). Need to buy a longer case or get the port opened up in the barrel then add the adjustable gas block.

I did take the gun to a friend that is a gunsmith today and he fired a couple of the rounds that I loaded with 3031 (in 2016) and it did not lock back on one round. Then he tried a couple factory loads and it worked. I am having him open the port a little on the barrel and installing an adjustable gas block. He is also going to tune it to the 3031 loads that I might have 800 loaded from a long time ago.

I never had an issue with the 3031 loads in a 16" gun. That is when I started thinking the powder did not burn quick enough to work in an 8.5" barrel.
 
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I prefer superlative arms bleed off adjustable gas block. Vents excess gas out the front rather than restricting the flow

This is what I am going with next. The SLR's always freeze. Good quality, but I'm done buying them.
 
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