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Adjustable gas block help

M

mzvarner

Sergeant
Full Member
Minuteman
Mar 7, 2013
510
378
Spokane, WA
Bought a new to me 308 wilson combat barrel that came with an adjustable block. I could not get it to fully lock back shooting 168gr FGMM. Dialed all the way in both directions. I even pulled both weights from the buffer. What do I do next? Chop a coil or 2 from the spring?

Edit: it's a wojtek weaponry brand, and I installed it per the instructions which want it offset from the shoulder the width of a credit card. Should I set flush with this shoulder?

Edit: Here are some measurements
Buffer length 2.5"
Complete buffer weight 3.7oz (104.89 grams)
Buffer weights 40.41 grams, 40.57 grams
Empty buffer (no weights) 23.47 grams
Buffer spring length 10 7/8 inches w/ 26 coils
 
Last edited:
Check the gas block alignment with the gas port... if that doesn't do it, then as @redneckbmxer24 said, a call to Wilson customer support would be the next step, if it were me.
 
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I second gas block alignment. Some gas blocks are set flush in the journal, some are set away a few thousandths and and I have seen nothing that says which components do what.
Unless you have a calibrated eye-ball or you have done a ton of these, your best friend is going to be a dimpling jig. It will have a pointed set screw that aligns the jig with the gas port. Flip it 180 and the other side will have drilled set screws that will align(or not) with existing dimples and will tell you if the gas block is properly aligned, and provides a guide to accuratly dimple your barrel if needed
 
Rlandry said:
I second gas block alignment. Some gas blocks are set flush in the journal, some are set away a few thousandths and and I have seen nothing that says which components do what.
Unless you have a calibrated eye-ball or you have done a ton of these, your best friend is going to be a dimpling jig. It will have a pointed set screw that aligns the jig with the gas port. Flip it 180 and the other side will have drilled set screws that will align(or not) with existing dimples and will tell you if the gas block is properly aligned, and provides a guide to accuratly dimple your barrel if needed
Click to expand...

This specific gas block uses 3 screws to clamp against the barrel, no dimple.
 
You can measure how far off the back of the gas block the hole is with a set of calipers. Then measure the gas port off the shoulder and find out it needs to be set off the shoulder or not, most of the time they do to get the port perfectly aligned with the hole in the block. Also really easy to rig the barrel up TDC and get the gas block TDC too.

I just assume that most people do that when putting them together, not eyeball it and call it good enough.
 
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I can't put my finger on it right now, but I have seen gas block alignment pins that go up through the gas port in the barrel and through the gas port in the barrel and the gas block. There are different size pins so you pick the one that fits the hole in your barrel. If I run across it again I'llposta link. I think I saw it on You Tube.
At any rate, it still sounds like a gas block alignment problem.
 
All I use is Wojeck Weaponry gas blocks anymore. Best value out there and they just work. The front screw is the gas adjustment and the side screw is to lock it in. You can remove both so not sure how you are going stop to stop.

If you flush up the front screw then back it out a few turns it will be wide open.
 
Rlandry said:
Unless you have a calibrated eye-ball or you have done a ton of these, your best friend is going to be a dimpling jig.
Click to expand...

Wojeck gas blocks are clamp on, not set screw types. I prefer clamp on as I have seen a lot of set screw types work loose.
 
How many click of adjustment do the Wojtek adjustable gas blocks have?
Thanks
 
Earnhardt said:
How many click of adjustment do the Wojtek adjustable gas blocks have?
Thanks
Click to expand...

It's a pretty long screw. I took it apart last night to make sure there was no obstruction, and found that really it's only about 4 or 5 threads between closed and wide open.
 
If you put a chamfer on the gas port about twice the size of the port it makes alignment less critical.
 
redneckbmxer24 said:
You can measure how far off the back of the gas block the hole is with a set of calipers. Then measure the gas port off the shoulder and find out it needs to be set off the shoulder or not, most of the time they do to get the port perfectly aligned with the hole in the block. Also really easy to rig the barrel up TDC and get the gas block TDC too.

I just assume that most people do that when putting them together, not eyeball it and call it good enough.
Click to expand...


This ^^^^^^^ with the variance in manufacturers & parts, can't imagine what anyone wouldn't verify correct position.

MM
 
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FWIW, my method of gas block alignment is a bore scope; just look up through the gas port, and align the hole in the block that way.

While I understand that not everyone has a bore scope, the availability of the less expensive video scopes have made it to where a lot of us can afford to have them.
 
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I had the same issue with an adjustable gas block in the past. I ended up getting a new one from the manufacturer and it worked as it should. If you are not able to close the gas off to the point where the bolt does not lock to the rear then it shouldn't be an alignment issue. I would contact Wilson.
 
The wojteks are made so that you can align the port visually or mechanically through the top of the block, then once it’s clamped in place install the gas tube. Also, if I recall, their instructions state to use a credit card or something to space the block off the shoulder.
 
Can you blow compressed air through the system and listen for max flow?
 
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So its truly variable with the adjustable threaded screw?....
Nice!
The SLR has 15 settings for an approx adjustment of 6.7% open/close per click...
 
Generally I was under the impression that the two set screw gas blocks have a set screw and the actual gas port drilled at the same time when produced. This makes it possible to flip the gas block over and align the gas port with the set screw hole. You can then mark the offset from shoulder. This will allow you to ensure the alignment front to back. Your Left/Right alignment should be pretty easy to find a well if you mark TDC.

Not sure if your 3 set screw block lines up a hole, but may want to give it a check.
 
Rlandry said:
I can't put my finger on it right now, but I have seen gas block alignment pins that go up through the gas port in the barrel and through the gas port in the barrel and the gas block. There are different size pins so you pick the one that fits the hole in your barrel. If I run across it again I'llposta link. I think I saw it on You Tube.
At any rate, it still sounds like a gas block alignment problem.
Click to expand...

These ?

http://uniquetek.com/product/T1511
 
I also think your GB alignment could be off.

If I missed it, sorry... what caliber ?

And make sure your new barrels chamber is thoroughly clean.
 
I edited the original post with some measurements but i will add them below as well. 308 gun shooting FGMM 168.

Aligning with a bore scope would be ideal. The gas tube is already pinned so should I take it out and try to align by looking down the hole? Any links to good methods to do this?

Edit: Here are some measurements
Buffer length 2.5"
Complete buffer weight 3.7oz (104.89 grams)
Buffer weights 40.41 grams, 40.57 grams
Empty buffer (no weights) 23.47 grams
Buffer spring length 10 7/8 inches w/ 26 coils
 
Distance from the shoulder to nearest edge of gas port is 0.253, on the gas block it measures 0.273. So I assume I can carefully hone this down on a flat surface (granite or glass) or on my fine DMT diamond plate?
 
Something seems off there... Did you contact wilson? Is the barrel drilled properly?
 
mzvarner said:
Distance from the shoulder to nearest edge of gas port is 0.253, on the gas block it measures 0.273. So I assume I can carefully hone this down on a flat surface (granite or glass) or on my fine DMT diamond plate?
Click to expand...

Measure to the center of the hole, not the edge; they are different size holes so comparing to center is the apples to apples correct way. Most low profile gas blocks are .300" from the rear edge to center of the hole.

You're not going to want to "carefully hone" that on a surface plate or diamond plate. You're talking about a process good for taking off a couple thousandths, and using it to take off 20+ thousandths.

The correct method would be to have the rear edge of your gas block milled down to the right dimension, if it is in fact incorrect, or get a more standard gas block that is .300" from the rear edge to center of the hole. It sounds like that standard .300" dimension probably matches your barrel. Personally I'd replace that gas block with something made to more common dimensions and discard that weird one.
 
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And this is why I ask questions. Good to know. On the wilson barrel it does measure .3 from the shoulder. On the gas block center is just a little further away. Sounds like a new gas block is my best bet?

My next question then, is an adjustable block worth it if I do not have the intention of suppressing. My only reason for switching is that it came with the barrel.
 
mzvarner said:
Distance from the shoulder to nearest edge of gas port is 0.253, on the gas block it measures 0.273. So I assume I can carefully hone this down on a flat surface (granite or glass) or on my fine DMT diamond plate?
Click to expand...

sounds like your GB is off.

usually it's the other way round, and either the channel in the GB is located same center as the barrel GB, or you end up spacing it about .015 to .030 from the shoulder, nominal thickness of AR-15 handguard cap.

if the hole in your GB is truly .273 away from the edge, I would use a different GB.

as an example, on my SLR Sentry GB, the distance from the edge of the GB to the edge of the hole is .2125, the hole in the GB is .124, and the barrel I was using, the edge of the barrel gas port was .2535 from the shoulder, with a gas port diameter of .072. this worked out to a .015 spacing between GB and barrel GB journal shoulder to get the 2 holes directly on top of each other concentric, for this particular example.

YMMV.
 
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rpoL98 said:
sounds like your GB is off.

usually it's the other way round, and either the channel in the GB is located same center as the barrel GB, or you end up spacing it about .015 to .030 from the shoulder, nominal thickness of AR-15 handguard cap.

if the hole in your GB is truly .273 away from the edge, I would use a different GB.

as an example, on my SLR Sentry GB, the distance from the edge of the GB to the edge of the hole is .2125, the hole in the GB is .124, and the barrel I was using, the edge of the barrel gas port was .2535 from the shoulder, with a gas port diameter of .072. this worked out to a .015 spacing between GB and barrel GB journal shoulder to get the 2 holes directly on top of each other concentric, for this particular example.

YMMV.
Click to expand...

I heard from Wilson Combat bright and early this morning. My buffer spring and weights all sounded correct. So the said try a new gas block and offered 3 recommendations. I ordered one and will post the results.
 
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I bet the new gas block does the trick.

The only thing an adjustable gas block does is allow you to adjust how much gas comes back to cycle the action. If after adjusting it and the rifle kept functioning as it should, then you had it aligned properly . The adjustable gas block is not doing its job properly by completely closing off the gas, therefore its fucked and a new adjustable gas block is needed.

No need to make rocket science out of it like others suggested.
 
Update for anyone that was interested. It's being shipped back from WC. They found it was under gassed and opened up the gas port.
 
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