6 Arc

William Suter said:
... Gas blocks are fairly cheap if you don't need best of the best. I'll replace it with an adjustable one...
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If it's short-stroking, an adjustable gas block is not going to help. They can only restrict the amount of gas, not give you more.
What is the barrel length and gas system length? I have a 18" 22 ARC with rifle length gas that was short stroking since day 1. I had to drill out the gas port a hair to get it to run right.
 
Well, that may or may not be appropriate, depending on the barrel length. Generally, Rifle + 1 would be fine on a 20", but not work at all on a 16".
However, gas port size plays a role too. Not all manufacturers use the same port size. The two must work together to ensure reliability. For example, an 18" with Rifle-length gas, or a 16" with Mid-length are typically good combos, but if the gas port is undersized, you will be under-gassed.

On the flip side, adding a suppressor can take a known good combo and push it into the over-gassed range. That one you can fix with an adjustable gas block, and optionally, a heavier buffer.
 
Sorry guys but I have no idea what rifle+1 means. (Told you I'm not an AR guy.........yet.) But the rifle has an 18" barrel.

What if I switched lowers? I can put my other lower on the Arc upper. If the problem goes away would that mean the issue is in the lower and not the upper?
 
Cut and paste

A "rifle +1" gas tube refers to a gas tube for an AR-15 style rifle that is one inch longer than a standard rifle-length gas tube. It's a non-standard length, designed to be used with barrels that have a gas port located further down the barrel than a standard rifle-length gas system. This setup is sometimes chosen for longer barrels or specific calibers to optimize gas pressure and cycling

I'm not an AR guy either. I just see a lot of people recommend a rifle +1 to fix cycling issues with the 6 arc.
 
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William Suter said:
Sorry guys but I have no idea what rifle+1 means. (Told you I'm not an AR guy.........yet.) But the rifle has an 18" barrel.

What if I switched lowers? I can put my other lower on the Arc upper. If the problem goes away would that mean the issue is in the lower and not the upper?
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So a Rifle + 1 gas system would be where the port is approximately 13" from the extension end of the barrel. It's a non-standard gas length. I've seen Rifle +2 as well, but usually only on longer (21"+) barrels.

You should be able to tell what you have using a tape measure. Considering this is a mass-produced BCA 18", I would bet either Mid-length or Rifle. Probably Mid since manufacturers tend to err on the side of over-gassing.

While it's unlikely that it's a lower problem, trying a different lower and different magazines is a good test. If it still happens then, you can focus on the upper.
 
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You can swap lowers to rule that out, but its most likely an issue with the upper. locking back on a empty mag by hand doesnt mean anything except the mag catch is working by hand. Under gas is a different story. Iv seen gas blocks not back all the way cause short stroking. I would swap in quality gas rings since the round count is unknown and your dealing with a BC.
 
I watched a video on checking your gas rings. Mine passed the test. Basically standing the bolt carrier on end and it didn't push the bolt back into the carrier. I didn't dis-assemble the carrier group to make sure the gaps weren't all aligned the same.

OK, I had to run an errand and went by a local shop here in town that specializes in AR rifles and a few parts. I asked about an adjustable gas block and he ask me why I thought I needed one. I told him on my last shot my bolt won't stay open on an empty mag. He said an adjustable gas block isn't going to fix my problem. He explained why and it made sense to me. The hole in the gas block is larger than the hole in the barrel. A gas block only lessons the gas, not gives it more. He said my issue is I need to enlarge the port in my barrel. Does this make sense? Is he possibly correct?
 
William Suter said:
... I asked about an adjustable gas block and he ask me why I thought I needed one. I told him on my last shot my bolt won't stay open on an empty mag. He said an adjustable gas block isn't going to fix my problem. He explained why and it made sense to me. The hole in the gas block is larger than the hole in the barrel. A gas block only lessons the gas, not gives it more. He said my issue is I need to enlarge the port in my barrel. Does this make sense? Is he possibly correct?
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Yes, this is what I said in post 23: "If it's short-stroking, an adjustable gas block is not going to help. They can only restrict the amount of gas, not give you more."
However, there are a number of other potential causes I mentioned in post 16 that I would look into before enlarging the gas port, which should probably be considered the last resort.
 
yes he is correct
Did you try a different load first?
If so.
I would think about changing (installing) to a new gas tube.
But would remove the gas block and tube first carburetor cleaner will help to clean the existing setup use the little straw to send the cleaner in both direction (from tube to block then from block to tube for final clearing I hope that makes sense) use air to blow everything out. Also check for dings, dents, & pin holes
IF you can get the tube and block to sit in Hoppes #9 for a soak then use compressed air to blow out, for several days soak blow out soak blow out. (fastest method is installing a new gas tube, and are not that expensive, and my cleaning solution is just being a cheapskate)

Now that the gas block is off take a pipe cleaner with hoppes#9 or CLP and clean the gas port on the barrel. blow it out with air.
WHY maybe enough crud is caked on inside the tube restricting the flow or a slight pin hole is allowing gas to escape that you failed to notice. For the barrel gas port it's just simply ensuring that a burr isn't covering obstructing the port or carbon build up started. And that isn't common (actually very rare) nor usually required, just a basic check.

I hardly ever recommend having the gas port in the barrel drilled out to the next size up, but you might have to have it done. If you tried a different load and new tube installed and it continues. (I have a suspicion, wished we lived closer to each other. it is probably a simple fix)
SuppressYourself beat in relying LOL

there is a million things many of us can type that should help you but maybe a pic of the gas block with tube (handguard off) would help. the block may simply be set against the gas block shoulder some are offet some are designed to sit against the shoulder. That would /could restrict the gas flow off setting the gas hole in the block and gas port in the barrel. If a gap is needed the gap between shoulder and block should be 0.025".
Now are there some blocks that are designed to sit to the shoulder without a handguard cap yes a few (hence the no 0.025" gap required).
But you said BCA which means they will source the most cost effective parts. Which tells me that they probably used a block that can be used with a hand guard cap (that cap is approx 0.025" thickness). The new gas tube install is just insurance to find the solution as it would most overrule crud built up or pin hole you may or may not see.

(most barrel manufactures will dimple the barrel 180 degrees from the gas port to assist in the line up... not all do this. if yours has this great now line up the back setscrew to the index dimple when installing as the back bottom set screw is in alignment with the gas hole in the block).

gas block with set screws

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Looking at BCA web site for gas block they offer
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video from brownell's gas block alignment



Now could your gas block have to be set against the shoulder or need a 0.25" gap to properly align ? yes to both.
 
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I googled gas port size on a BCA barrel and it said .0935. I have a drill bit that is the same size. It won't even begin to go in the port on the barrel. As for the block and tube, its gotten cleaned twice now and doesn't seem to be blocked.

As of now, I'm shooting factory fodder until I get a little brass accumulated. It shoots the Hornady Black so well I may not reload for it.
 
If you do end up drilling out the gas port, I know I said it's pretty much the last resort, but it's also no big deal. Just use a set of drill bits and keep trying them and sizing up until one won't fit. Use that one.
I just placed a cleaning jag inside the barrel at the port location to prevent the bit from hitting the other side (going too deep) and drilled it out with a hand drill.
 
I appreciate all the tips that all of you have given. AR's are fun to shoot but I'll be the first one to admit I know only the basics on how they function. My thoughts were.... if drilling out the hole and possibly making it to large and now causing a different issue, that an adjustable gas block would remedy that problem. I can go smaller just not larger. But I also gave it another good cleaning and plan to run the BCG with a little more oil to see if that might solve the issue before using the drill. I just don't want to start throwing new parts on it if I don't need to.

Thanks again!!!
 
ha. if it shoots as well as you say it does and all you want to do is hunt with it...... just leave it alone and go kill stuff. pew pew pew
 


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