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Posted: 11/14/2021 1:45:25 AM EDT
So I just completed a form 1 with a quietbore, and the sound reduction is great. As in, no pain or muting in the ears (not that I'd do it a lot) whatsoever good. I'm very pleased.

But the blowback, god dayam. The overwhelming smell is one thing, but the stinging in the eyes... Yeah, I'm going to be getting an adjustable gas block.

I see that Aero makes one, but any suggestions are welcome. As well as tips and pointers that I'll need...?

Bonus question: with a long rail, being unable to get calipers over my barrel, anyone happen to know what size an 5.56 LWRC DI barrel is?
Link Posted: 11/14/2021 1:51:01 AM EDT
[#1]
Shocker.
Link Posted: 11/14/2021 2:48:45 AM EDT
[#2]
Start with your charging handle. PRI Gas Buster CH or a DIY mod. are two options. There are a number of way to restrict the gas other than a AGB, and what would work best depends on whether you run suppressed all the time or switch back and forth. Access to the AGB for adjustments can be a issue depending on factors like barrel length/handguard length.
Link Posted: 11/14/2021 2:53:22 AM EDT
[#3]
A Radian Raptor SD charging handle is an option.
Link Posted: 11/14/2021 2:57:22 AM EDT
[#4]
Would second starting with the CH before trying to tap off gas at the block. Adjustable blocks can be fine, they can also not be fine (seizing and general shenanigans if not maintained with frequency). A gas buster may not solve all your problems, but it will very likely help.

Other options worth considering: BRT gas tubes and the Bootleg adjustable carrier. I use both across four rifles and they're preferable to agbs in my opinion.
Link Posted: 11/14/2021 1:02:29 PM EDT
[#5]
Geissele charging handles work for me.
They have a bigger ledge on the back side.
Attachment Attached File


Link Posted: 11/14/2021 1:32:11 PM EDT
[#6]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Geissele charging handles work for me.
They have a bigger ledge on the back side.
https://www.ar15.com/media/mediaFiles/413870/img_0823_jpg-2166509.JPG

View Quote



What receiver is that?  I'm liking that steel insert where the CH latch grabs it.
Link Posted: 11/14/2021 1:39:58 PM EDT
[#7]
Quoted:
But the blowback, god dayam. The overwhelming smell is one thing, but the stinging in the eyes... Yeah, I'm going to be getting an adjustable gas block.
View Quote

MOTO.
Link Posted: 11/14/2021 1:49:02 PM EDT
[#8]
Quoted:
So I just completed a form 1 with a quietbore, and the sound reduction is great. As in, no pain or muting in the ears (not that I'd do it a lot) whatsoever good. I'm very pleased.

But the blowback, god dayam. The overwhelming smell is one thing, but the stinging in the eyes... Yeah, I'm going to be getting an adjustable gas block.

I see that Aero makes one, but any suggestions are welcome. As well as tips and pointers that I'll need...?

Bonus question: with a long rail, being unable to get calipers over my barrel, anyone happen to know what size an 5.56 LWRC DI barrel is?
View Quote


If that's a complete LWRC upper, don't bother screwing with the gas block.  Just throw an adjustable carrier in and call it good.   There still isn't a solid adjustable gas block option that isn't a pain to install and maintain and yanking apart a built upper is a waste of time.

You're not getting gassed out by the gas coming through the gas tube and gas key; you're getting more residual pressure from the can coming back out through the chamber because you're extracting faster.

A Gemtech carrier will shoot some additional gas out the side of the carrier on the suppressed setting, but the improvement will be noticeable and you won't have to waste time and money confirming zero or re-zeroing like you might with gas block work.
Link Posted: 11/14/2021 2:12:48 PM EDT
[#9]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
You're not getting gassed out by the gas coming through the gas tube and gas key; you're getting more residual pressure from the can coming back out through the chamber because you're extracting faster.
View Quote


^This is exactly why I sold my piston upper

It got filthy suppressed because of gas blowing around the case

@Shinobi15 - what size drill bit did you use on the baffles and how big is your exit aperture?

Link Posted: 11/14/2021 8:02:01 PM EDT
[#10]
I used a 9/32 bit for everything.
Link Posted: 11/14/2021 8:35:51 PM EDT
[#11]
Are they cone baffles or K?

Did you clip them?
Link Posted: 11/14/2021 9:59:08 PM EDT
[#12]
cone cups, as seen here: https://www.quietbore.com/product/5-56-upgraded-form-1-kit/.

i only drilled, no clipping.
Link Posted: 11/14/2021 9:59:28 PM EDT
[#13]
Adjustable bolt carrier is what you need.  I use the Gemtec but the Bootleg might be better.
Link Posted: 11/14/2021 11:48:28 PM EDT
[#14]
Can your cups be aligned with each other?

If they can, I would clip those baffles

It will help with back pressure
Link Posted: 11/15/2021 12:05:39 AM EDT
[#15]
Doesn't matter what you do as a lefty, even with a piston. Get used to it. Us lefties are, even unspressed.
Link Posted: 11/16/2021 2:10:30 PM EDT
[#16]
Discussion ForumsJump to Quoted PostQuote History
Quoted:



What receiver is that?  I'm liking that steel insert where the CH latch grabs it.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Quoted:
Geissele charging handles work for me.
They have a bigger ledge on the back side.
https://www.ar15.com/media/mediaFiles/413870/img_0823_jpg-2166509.JPG




What receiver is that?  I'm liking that steel insert where the CH latch grabs it.



It’s a Colt Canada monolithic.  Incredibly rare in the US. The fact that the steel insert isn’t staked in as it should be and the profile of the round on the upper isn’t smooth like a forging makes me think it is an airsoft…
Link Posted: 11/16/2021 10:24:20 PM EDT
[#17]
Discussion ForumsJump to Quoted PostQuote History
Quoted:



What receiver is that?  I'm liking that steel insert where the CH latch grabs it.
View Quote
@Tan41
Sorry man, just read the rest of the thread now.
This is not my receiver, I just googled Geissele CH for the OP.

Link Posted: 11/17/2021 12:09:29 AM EDT
[#18]
Well, the first thing I'm going to be trying (have already started actually) is using permatex silicone gasket maker to seal around that charging handle. If that isn't enough, PRI gas buster charging handle will be on order.

Thanks all for letting me know about the charging handle fix, hopefully the cheap solution will work.

Would love to clip the baffles, but don't have a mill handy.
Link Posted: 11/17/2021 12:48:48 AM EDT
[#19]
No worries @thorn653
Link Posted: 11/17/2021 10:51:31 PM EDT
[#20]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Well, the first thing I'm going to be trying (have already started actually) is using permatex silicone gasket maker to seal around that charging handle. If that isn't enough, PRI gas buster charging handle will be on order.

Thanks all for letting me know about the charging handle fix, hopefully the cheap solution will work.

Would love to clip the baffles, but don't have a mill handy.
View Quote


I did the DIY gasket on a couple rifles and it works really well. you can get it to seal better than a machined part.
Nowhere near as pretty as the PRI but I'm a function over form guy
Link Posted: 11/18/2021 12:21:37 AM EDT
[#21]
Same here, and once I learned what was happening (thanks again everyone) it seemed to be a really good answer.

If it doesn't work well enough, I imagine I'll get the PRI... and gasket seal that one too!
Link Posted: 11/18/2021 6:29:12 AM EDT
[#22]
BRT gas tube, reduced size and all you gotta do is pop off the rail and swap gas tube.

Mine made a world if difference.
Link Posted: 11/18/2021 9:48:27 AM EDT
[#23]
A heavier buffer can help delay bolt unlock so you get less gas flowing back into the action through the breech.  Something like an H3 plus an adjustable gas block is a good idea IMO.  Some of the adjustable bolt carriers are very easy to adjust, but they might increase noise at the shooter's ear due to bleeding gas off at the ejection port.  The reduced size gas tubes also seem to work, but they aren't adjustable, and I would be concerned about the reduced port size on the thin gas tube quickly eroding.  SLR and SA gas blocks can be adjusted fairly easily even when under a handguard as long as you have the right tool with you.  Rifle Speed has a new gas block with an adjustment ring that can be setup to stick out from the handguard so you can quickly see the exact setting you are on, and adjust it without tools.
Link Posted: 11/18/2021 10:23:47 AM EDT
[#24]
What barrel?

what gas port size?

What buffer spring/weight combo?

Do some reading about how these affect the gas system on School of the American Rifle.

If severely overgassed, something like the BRT EZ Tune gas tube might be your best bet.

http://blackrivertactical.com/
Link Posted: 11/18/2021 11:35:09 PM EDT
[#25]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Adjustable bolt carrier is what you need.  I use the Gemtec but the Bootleg might be better.
View Quote



I agree.  I have both and the bootleg is much easier to adjust settings.  They work equally well.  The bootleg has 4 positions, but I only use the suppressed and unsuppressed.

Link Posted: 11/20/2021 10:06:16 PM EDT
[#26]
Well, the gasket maker seal worked pretty damn well. Still a lot of gas out the ejection port, naturally, but no longer in the face, burning the eyes, overwhelming the senses. So, massive improvement.

That said, I do wonder about long term lead levels shooting it a lot...
Link Posted: 11/20/2021 10:30:06 PM EDT
[#27]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Well, the gasket maker seal worked pretty damn well. Still a lot of gas out the ejection port, naturally, but no longer in the face, burning the eyes, overwhelming the senses. So, massive improvement.

That said, I do wonder about long term lead levels shooting it a lot...
View Quote


If you shoot and/or reload it's smart to have a lead test done by your Dr. I have one done every 2-3 years
Link Posted: 11/20/2021 10:30:44 PM EDT
[#28]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Well, the gasket maker seal worked pretty damn well. Still a lot of gas out the ejection port, naturally, but no longer in the face, burning the eyes, overwhelming the senses. So, massive improvement.

That said, I do wonder about long term lead levels shooting it a lot...
View Quote

Glad it worked out. As far as the lead, wear a P-100 mask, use solids or Kalifornia compliant ammo if it concerns you.
Link Posted: 11/21/2021 1:02:17 AM EDT
[#29]
Discussion ForumsJump to Quoted PostQuote History
Quoted:

Glad it worked out. As far as the lead, wear a P-100 mask, use solids or Kalifornia compliant ammo if it concerns you.
View Quote


Well, I was thinking I'd mostly practice without the thing if I don't use another method to mitigate the extra gas coming out the ejection port.
Link Posted: 11/21/2021 1:08:34 AM EDT
[#30]
Discussion ForumsJump to Quoted PostQuote History
Quoted:


Well, I was thinking I'd mostly practice without the thing if I don't use another method to mitigate the extra gas coming out the ejection port.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Quoted:

Glad it worked out. As far as the lead, wear a P-100 mask, use solids or Kalifornia compliant ammo if it concerns you.


Well, I was thinking I'd mostly practice without the thing if I don't use another method to mitigate the extra gas coming out the ejection port.

You could always go piston.
Link Posted: 11/21/2021 1:35:52 AM EDT
[#31]
Yeah, but at that point I might as well just get another rifle. I've also heard it said that it didn't help much, though I don't understand how that could be.

Another thing I'm confused about- how would a heavier bolt (or spring, for that matter), make a difference? The higher pressure is still reaching the chamber, right? The physics of it make me think that either a different sized gas block or tube would be the only way to lower the pressure coming back into the chamber.
Link Posted: 11/21/2021 2:12:19 AM EDT
[#32]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Yeah, but at that point I might as well just get another rifle. I've also heard it said that it didn't help much, though I don't understand how that could be.

Another thing I'm confused about- how would a heavier bolt (or spring, for that matter), make a difference? The higher pressure is still reaching the chamber, right? The physics of it make me think that either a different sized gas block or tube would be the only way to lower the pressure coming back into the chamber.
View Quote

In my experience the majority of the gas you are getting is from the chamber opening and gas coming down the bore, I have a piston AR and the only gas that you experience is from the chamber opening. I've tried the same can on a gas gun that was well known to be over gassed and there was little difference between the two.

It felt like going from full power Lake City M855 to weak but clean burning 55gr .223 made the biggest difference. If you shoot dirty shit tier steel (nothing wrong with saving money to have fun) expect there to be gas.

The only things besides ammo that helped a little was a heavier buffer, which most likely kept the bolt closed longer, hence less gas being forced toward the shooter, in conjunction with decent charging handle.
Link Posted: 11/21/2021 11:56:52 AM EDT
[#33]
Discussion ForumsJump to Quoted PostQuote History
Quoted:

In my experience the majority of the gas you are getting is from the chamber opening and gas coming down the bore, I have a piston AR and the only gas that you experience is from the chamber opening. I've tried the same can on a gas gun that was well known to be over gassed and there was little difference between the two.

It felt like going from full power Lake City M855 to weak but clean burning 55gr .223 made the biggest difference. If you shoot dirty shit tier steel (nothing wrong with saving money to have fun) expect there to be gas.

The only things besides ammo that helped a little was a heavier buffer, which most likely kept the bolt closed longer, hence less gas being forced toward the shooter, in conjunction with decent charging handle.
View Quote


Quick side note- how is it that piston guns have gas going into the chamber? I thought the whole point was that a piston connected to the bcg, and the gas pushed the piston from the other end, as seen here: https://www.youtube.com/watch?v=jsMzuKw7zzM&ab_channel=RevelMotionDesign
Link Posted: 11/21/2021 4:16:07 PM EDT
[#34]
Piston guns extract faster than guns with gas tubes.

With a gas tube, when the bullet passes the gas port the carrier is pressurized and two things happen - the carrier begins its rearward travel and the bolt is pushed forward.

That second part is critical, since it helps maintain a seal longer at the chamber.

In a piston gun, an op rod pushes against the carrier and the bolt is yanked out of battery faster than normal and this allows gas to blow by the case as it’s being extracted.

I had an LWRC upper that got absolutely filthy when I shot it suppressed, ended up selling it because it didn’t stay any cleaner than any of my other guns.
Link Posted: 11/21/2021 5:12:51 PM EDT
[#35]
Now I get it...

Which makes me think tuning the gas block/tube differently would solve this, as you would theoretically get the a delayed chamber seal opening... Then again, it may make no difference, since the back pressure in the bore exists no matter what.
Link Posted: 11/21/2021 7:29:56 PM EDT
[#36]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Now I get it...

Which makes me think tuning the gas block/tube differently would solve this, as you would theoretically get the a delayed chamber seal opening... Then again, it may make no difference, since the back pressure in the bore exists no matter what.
View Quote


You are getting there with delaying the cycling.

I explained poorly above, tuning gas is more about timing of the carrier than the gas travelling down the gas tube. A heavier buffer and adjustable gas tube turned down will help some with back pressure, but it's still more can and ammo specific than most other factors.

You have to remember that right after you shoot the can itself is full of gas and the pressure is going to try to spread out, and the sooner your chamber opens, the more pressure there is driving gas back down the barrel. If I take the op rod off my 416 upper and shoot with a can I get pretty much zero gas to the face because the chamber doesn't open until I charge the weapon again, and by that point the gas had nowhere to go but out the end of the can.
Link Posted: 11/21/2021 8:07:10 PM EDT
[#37]
Burning gun powder.

Link Posted: 11/22/2021 4:16:39 PM EDT
[#38]
Discussion ForumsJump to Quoted PostQuote History
Quoted:


You are getting there with delaying the cycling.

I explained poorly above, tuning gas is more about timing of the carrier than the gas travelling down the gas tube. A heavier buffer and adjustable gas tube turned down will help some with back pressure, but it's still more can and ammo specific than most other factors.

You have to remember that right after you shoot the can itself is full of gas and the pressure is going to try to spread out, and the sooner your chamber opens, the more pressure there is driving gas back down the barrel. If I take the op rod off my 416 upper and shoot with a can I get pretty much zero gas to the face because the chamber doesn't open until I charge the weapon again, and by that point the gas had nowhere to go but out the end of the can.
View Quote


Okay...

So, if more of a delay were required, would you expect the brass to be flying 1-2 o'clock, ish? (Because the additional pressure would also be coming down the tube and be slamming it back faster?)
Link Posted: 11/22/2021 5:00:43 PM EDT
[#39]
Lefty shooter here as well.

I'm going to save you some hassle and money.

Embrace the suck.

Seriously, shoot a bunch and you will get over it, your eyes will get tough and quite tearing up like little girls.

Pinned - non adj gas blocks, regular bcg, no special shit = FTW.

I like the blowback now, reminds me I'm alive...
Link Posted: 11/22/2021 7:04:34 PM EDT
[#40]
Discussion ForumsJump to Quoted PostQuote History
Quoted:


Quick side note- how is it that piston guns have gas going into the chamber? I thought the whole point was that a piston connected to the bcg, and the gas pushed the piston from the other end, as seen here: https://www.youtube.com/watch?v=jsMzuKw7zzM&ab_channel=RevelMotionDesign
View Quote


The can traps pressurized gas much longer.  It's not just releasing it out the front, it's also coming out the chamber end.   This is why the brass from when you shoot suppressed is so dirty.

I shoot bolt guns with cans as well - that brass is 100% pristine when it comes out.  In fact, dirty brass is actually an extreme under-pressure sign for handloading, because it means you didn't have enough pressure to inflate the brass against the chamber walls and fully seal off the gas.
Link Posted: 11/23/2021 1:08:20 AM EDT
[#41]
Now that I think about it, a heavier spring might also help things, no?
Link Posted: 11/23/2021 2:20:22 AM EDT
[#42]
Quoted:


Okay...

So, if more of a delay were required, would you expect the brass to be flying 1-2 o'clock, ish? (Because the additional pressure would also be coming down the tube and be slamming it back faster?)
View Quote

Yep, my ideal is the 3-4 o'clock, if your brass is ejecting forward of that, it's a sign of high bolt velocity, something that is caused by the increase of back pressure.

Quoted:
Now that I think about it, a heavier spring might also help things, no?
View Quote

Yes, but some would recommend against it. I just used a high quality standard weight spring, that way I don't need to rely on a high-ish wear part that the performance of gets worse as it is used to get what I want out of a rifle... not that most people ever shoot enough to wear out a buffer spring. For the sake of simplicity when tuning a gun, I like to use one weight of spring, the closer to base the easier it is to diagnose if that makes sense.

I would try messing with just buffer weights first, it would be very easy to go overboard with a stiff spring + heavy buffer and end up with a self ejecting bolt action rifle.
Link Posted: 11/23/2021 3:07:04 PM EDT
[#43]
Hm.

So to conclude, for now:

To delay the bolt movement, I can...

- Try playing with an adjustable gas block
- Play with a different gas tube
- Mess around with stiffer buffer springs
- Use a heavier buffer weight

And, for sake of simplicity, a heavier buffer weight is the best first option.

Well, it happens that I have JP's captured spring in my build, so perhaps I should look into what they have...
Link Posted: 11/23/2021 3:22:40 PM EDT
[#44]
Buy a PWS, buy once, cry once.  No gas face.
Link Posted: 11/23/2021 3:30:35 PM EDT
[#45]
LMT FA Enhanced BCG is designed to help with the gas issue. One aspect is the cam pin path design that delays the bolt unlocking.
Link Posted: 11/23/2021 9:00:41 PM EDT
[#46]
You need to find someone with a mill who can help you clip those baffles

You’re going to make all these changes to your host, but what happens when you put the can on a different rifle?

You’re going to run into the same issue that you’re experiencing now

Clipping the baffles will make a difference in back pressure, I would fix that first then think about modifying the host if the results aren’t satisfactory

Link Posted: 11/23/2021 10:06:15 PM EDT
[#47]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Well, the first thing I'm going to be trying (have already started actually) is using permatex silicone gasket maker to seal around that charging handle. If that isn't enough, PRI gas buster charging handle will be on order.

Thanks all for letting me know about the charging handle fix, hopefully the cheap solution will work.

Would love to clip the baffles, but don't have a mill handy.
View Quote



You can use a file or dremel for clipping if you want
Link Posted: 11/24/2021 12:51:20 AM EDT
[#48]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
You need to find someone with a mill who can help you clip those baffles

You’re going to make all these changes to your host, but what happens when you put the can on a different rifle?

You’re going to run into the same issue that you’re experiencing now

Clipping the baffles will make a difference in back pressure, I would fix that first then think about modifying the host if the results aren’t satisfactory

View Quote


If I can make sure to do it properly, I'm totally down to clip the baffles. But I don't really plan on putting this on another rifle, certainly not any time soon. Which is why I figure, eh, if I can keep it cleaner on the inside, all the better, since I plan on keeping this rifle for a long long time.
Link Posted: 11/24/2021 12:47:15 PM EDT
[#49]
An adjustable gas block made a much bigger difference in gas to the face for me than did the gas buster charging handles and silicone.



All of my adj blocks are JP and they work great.  Make sure whatever you get will work with your handguard.
Link Posted: 11/24/2021 12:53:56 PM EDT
[#50]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Doesn't matter what you do as a lefty, even with a piston. Get used to it. Us lefties are, even unspressed.
View Quote



I agree.

But putting in a heavier buffer and spring helped my cheapo Palmetto pistol (which was already over-gassed) quite a bit.

At least to my unscientific face, it seemed much improved.  

You do get very persnickity about eye-pro though.
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