AR buffers to borrow for testing

[Calculon]

Warfab - now that you mention it there is a LOT of carbon on the tube where it enters the block. Could it be a leak/bad seal?

[WARFAB]

Could it be a leak/bad seal?

That's what I was wondering. I'm not sure if it could be a parts compatibility issue or if perhaps the gas tube wasn't inserted and pinned into the gas block correctly.

[Calculon]

You mean this is a problem?

[Meketrefe]

The gas tube is still in gas block. Do uouvthink it's worth taking off and te installing? I can take a better pic if helpful.

That gas block seems to be leaking too much. Most times this is due to the gas tube slot being out of spec (too large) but it could be a tube or both.
You can take it out clean everything with solvent and then put it back on but take it out 1/8" or so, put a drop of blue locktite and then put it back in and pin it.
Just so it smears all round but not inside the actual port. Let it cure overnight.

Also take a 1/16" bit and make sure it goes in and out the barrel port w/o problems. if you have to run it with a drill make sure you use a drill press and set up the
stop so it will only go past the thickness of the bar and will not touch the bore on the other side.

Next time consider an adjustable gas block with clamp and made of steel that is so much easier to install and provides a better seal all aorund.
These are a good deal and are also very tight where the tube mates the block.

http://www.bte-usa.com/#!bte-micro-gas-blocks/c1du

Whatever the gas block always blue locktite any screws.

[Calculon]

I'll order one today rather than put the old one back on. The link shows 2 sizes: 0.75 and 0.625. How do I know which is correct?

Also should I just replace the gas tube as well?

[Meketrefe]

I'll order one today rather than put the old one back on. The link shows 2 sizes: 0.75 and 0.625. How do I know which is correct?

Also should I just replace the gas tube as well?

measure your barrel diameter with the calipers. normally they are 0.75 but sometimes they are .625 and do not have to be pencil barrels for that.
Also that pin must be driven all the way in.

[Calculon]

That gas block seems to be leaking too much. Most times this is due to the gas tube slot being out of spec (too large) but it could be a tube or both.
You can take it out clean everything with solvent and then put it back on but take it out 1/8" or so, put a drop of blue locktite and then put it back in and pin it.
Just so it smears all round but not inside the actual port. Let it cure overnight.

Also take a 1/16" bit and make sure it goes in and out the barrel port w/o problems. if you have to run it with a drill make sure you use a drill press and set up the
stop so it will only go past the thickness of the bar and will not touch the bore on the other side.

Next time consider an adjustable gas block with clamp and made of steel that is so much easier to install and provides a better seal all aorund.
These are a good deal and are also very tight where the tube mates the block.

http://www.bte-usa.com/#!bte-micro-gas-blocks/c1du

Whatever the gas block always blue locktite any screws.

1/16 was way too small. Port diameter best fit by a 5/64 bit. Just twisted by hand and seems pretty smooth. Looks like I will be removing and reinstalling gas tube as thread protector is slightly larger than barrel i.e. Gas block will not slide over it. I'll reinstall with blue loctite and see if it improves gas seal and performance of action. I hope this works or next step is drill out pin and remove thread protector.

Thanks all.

[Meketrefe]

1/16 was way too small. Port diameter best fit by a 5/64 bit. Just twisted by hand and seems pretty smooth. Looks like I will be removing and reinstalling gas tube as thread protector is slightly larger than barrel i.e. Gas block will not slide over it. I'll reinstall with blue loctite and see if it improves gas seal and performance of action. I hope this works or next step is drill out pin and remove thread protector.

Thanks all.

5/64 is more than plenty. check the gas tube and use a drop of blue locktite around the tube but w/o smearing into the port. after cured do a test by covering both ends of the barrel
and blowing on the gas block. you should feel it holds the pressure. then follow the other A, B, C, etc... steps as it explained.
good luck.

[Calculon]

Update - looks like I have a bad/leaking gas block (see pics) but I'm wondering if there could be another issue as well. Guess I'll have to so down process of elimination. Pics first.

I loosened gas block and removed gas tube to clean carbon from prior photos above. Scrubbed clean and reinstalled with some blue loctite around tube as Meke suggested. Let sit overnight and then went to range. As you can see in the pics, gas is leaking at front edge of block and around gas tube after approx 100 rounds fired. In order to change out block I'm going to have to drill pin out of thread protector as block won't ride over it. Do you think I will be able to reuse thread protector is careful drilling out?

[Calculon]

Update part deux:
I write this to see if you folks more knowledgeable on the platform may recognize an issue I'm searching for. At range yesterday the stovepipes began within the first 10 rounds so the gas block issue above may be the culprit. To try to determine what the issue could be I brought 2 similar rifles to the range so I could swap out parts to identify the problem. Both are carbine length with exact same stock, buffer tube, buffer and spring. I'll call problem rifle MSR1 and other MSR 2.

MSR 1	MSR2
Stovepipes began 1st 10 rd mag	Flawless operation
Swapped BCG & CH from MSR2 - stove pipes continue	Using MSR1 BCG & CH, no issue
Complete upper from MSR2 on complete MSR1 lower - no issue	Complete upper from MSR1 on MSR2 - no issue
Reassemble MSR1 upper and lower - stovepipes	Reassemble MSR2 upper and lower - flawless

Was wondering if there could be a spring/buffer issue here as well - any thoughts? Should I just replace gas block first then see what happens?

[Meketrefe]

Happy new year.

When you put the faulty upper from MSR1 in the MSR2 lower w/o doing anything else did you get the same problems? If this gives problems you know know the problem is withing the upper itself and it has nothing to do with the buffer, hammer, magazine, etc...? In other words you wan to insulate the root cause by the method of elimination starting with the most obvious that is swapping the entire upper as-is.

In MSR2, when you blew in the gas tube covering both the crown and the breach with your palms did you feel the steady pressure? This is a good way to identify if the tube holds pressure.
Also w/o covering anything you should be able to blow plenty of air without disruption almost as it was a drinking straw.
We also assume there are no frictions of any kind and the carrier moves freely w/o any obstructions of any kind. Excessive hammer pressure can be the issue.
With this it is reasonable to think same dimensions, same BCG will produce the same results so the only thing left is to address the gassing problems.

If you have a thread protector that is larger than the diameter than the glas block and pinned you put yourself into a corner but what is done is done so now you can deal with this in three ways:

A) Drill out the blind pin w/o going too far past the threads to make sure you do not take more from the minor diameter of the barrel. After this you should be able to remove the protector using a brake wrench.

B) Cut the existing gas block with a dremel or a mill. do this at the bottom where you already have the gas block tapped. and even if you put a scuff in the
barrel will not have an effect on the performance like on the other side that is where the port is and this is delicate.

Then after you could use a 2 piece gas block like YHM has one. This gas block will not fit under some handguards that go over the port.
If the thread protector diameter is not much longer one could use a clamp block that can open up about 50 to 60 thousands so it can be moved forward.
If you tell me the diameter of the protector I can tell you the max diameter a clamp one can be opened to see if it will slide past the protector.

C) Put the barrel in a lathe and turn the thread protector to match flush the diameter of the barrel at that point. You need access to a lathe or someone
with a lathe. This is actually the easiest way but machinist tooling is needed.

[Calculon]

Happy new year.
- To you also - thanks.

When you put the faulty upper from MSR1 in the MSR2 lower w/o doing anything else did you get the same problems?
- When I swapped uppers and lowers problem disappeared. This is what got me thinking maybe something in addition to gas leak may be at play. Plus when I switched ONLY the bcg's the problem did not go away - that is with bcg2 in MSR1 I still got stove pipes and jams in MSR1. Putting bcg1 into MSR2 had no impact on MSR2 - it performed without error.


In MSR2, when you blew in the gas tube covering both the crown and the breach with your palms did you feel the steady pressure? This is a good way to identify if the tube holds pressure.
Also w/o covering anything you should be able to blow plenty of air without disruption almost as it was a drinking straw.
- I did not try either of these tests but will try when I have some time.

We also assume there are no frictions of any kind and the carrier moves freely w/o any obstructions of any kind. Excessive hammer pressure can be the issue.
- I'd like to talk more about this and how to resolve. You mentioned adjusting hammer spring. How much and do I have to disassemble?

If you have a thread protector that is larger than the diameter than the glas block and pinned you put yourself into a corner but what is done is done so now you can deal with this in three ways:

A) Drill out the blind pin w/o going too far past the threads to make sure you do not take more from the minor diameter of the barrel. After this you should be able to remove the protector using a brake wrench.

B) Cut the existing gas block with a dremel or a mill. do this at the bottom where you already have the gas block tapped. and even if you put a scuff in the
barrel will not have an effect on the performance like on the other side that is where the port is and this is delicate.

Then after you could use a 2 piece gas block like YHM has one. This gas block will not fit under some handguards that go over the port.
If the thread protector diameter is not much longer one could use a clamp block that can open up about 50 to 60 thousands so it can be moved forward.
If you tell me the diameter of the protector I can tell you the max diameter a clamp one can be opened to see if it will slide past the protector.

C) Put the barrel in a lathe and turn the thread protector to match flush the diameter of the barrel at that point. You need access to a lathe or someone
with a lathe. This is actually the easiest way but machinist tooling is needed.

- Would like to avoid drilling out pin if I can. No access to a large or mill. Will investigate the YHM 2 piece block to see if it will fit under handguard.

Thanks again for the guidance.

..

[Calculon]

Here's a couple of the nastier jams for your viewing pleasure.

[thughes]

OMG! Is that green tip armor piercing cop killer ammo? Thank God your rifle jams, you could kill somebody with that stuff.

[Meketrefe]

Lets try to do something for the gas block later but I think this is what we know and correct me if I am wrong:

MSR1 upper works in MSR2 lower.
MSR2 upper works in MSR1 lower.
MSR1 upper has enough gas and no obstructions to work in MSR2 lower.
MSR2 upper also has enough gas to work in MSR1 lower.

Lets try this:

Disassemble MSR1 lower. We are going to condition the hammer spring to remove some pressure. at the base of the coil bend it a little like 30 degrees with the direction of the coil
so next times those two legs that go over the trigger pin have less pressure. Also make sure you check any other friction points in the tube, buffer stop or even a bolt catch out of spec.
The bolt lugs should not touch anything, including the magazine lips.
My thinking is MSR1 upper has enough pressure even with the leak to overcome and cycle ocrrectly in MSR2 lower so lets try to make sure MSR1 lower is as smooth or more as MSR2 lower.
might also want to test with the same buffer and spring in MSR2 to discard that.
I would address the gas block leak with blue locktite and then replace later in case that is not enough.
Make sure the buffer tube is the same diameter and depth dimension as MSR2 lower and might also want to drill a small 1/8 hole in the back of the buffer tube. Most buffers should have one but sometimes this is not present or covered with paint or burrs. This allow built air pressure to escape. If a stock is covering the hole it should be drilled too to allow it to breath.

Those bullets look like the aftermath of typical stove pipes.