AR Gas Vent

[gatordev]

This is my initial take so far...

So I thought this thing might be a gimmick. I bought this almost two years ago when I was putting together my MK18 and doing the NFA dance with my suppressor, but I never bothered to install it. I figured I'd get to it eventually and last night was finally that time.

The premise is that this vents the gas away from the shooter's face at the charging handle and instead dumps the gas overboard on the right side (or on the forward assist side) of the rifle. Other methods out there are to use some sealant on the charging handle where it meets the receiver. I haven't tried that yet, but I'm curious to do it on another rifle some time.

While I certainly get gas in the face on my other rifles, I find the longer the barrel (or maybe it's the gas system), the less of an issue it is. However, my MK18 is pretty bad if you start putting several strings of fire together. So today's test coincided with running 60 rounds through the gun while I functioned tested a new bolt (old one broke). I was doing a couple of simple drills between two targets. Sometimes I was doing a reload drill, sometimes I would do a transition from strong to weak side. I also ran a couple of rounds through it faster during several strings just for good measure.

Here it is installed:





Results:

So certainly a small sample test today, and I plan to continue to run this for a while to see how I like it, but I have to admit, I was surprised how well it worked when shooting right-handed. It didn't completely eliminate gas in the face, but it was significantly improved. I could also tell it was dumping gas because when I would shoot left-handed, I'd all of a sudden get lots more gas, but that makes sense given where it is located.

I picked this thing up from Weapon Outfitters during one of their sales. You can find them here:

http://www.weaponoutfitters.com/ar-gas-vent.html

Pros:

-Easy to install (although my roll pin didn't want to go all the way down when I put it in last night).
-Seems to reduce gas for right-handed shooter.
-Didn't have any function issues due to a potential "change" in the gas flow.

Cons:

-Not so great for a left-handed shooter (or shooting weak handed on a lefty upper).
-Eliminates the ability to have a forward assist, if that's important to you.
-Not inexpensive (but not terrible).

As I use it more, I'll post an update.

[gatordev]

Grrr...Photobucket is pissing me off. The first picture is rotated in PB, but not here on the forum. Sorry for the weird angle.

[UWone77]

Nice to hear someone else with a review on one of these. I know Roy at WO is pretty high on them, but admitted they don't work well for left handed shooters like me. I guess I'll just have to resign myself to gas in the face whenever shooting the AR platform.

[FortTom]

This is more of an aside, than a direct comment, because I'm not running a can on anything, but for those, especially in dusty conditions, that are getting "raccoon eyes" from a rifle that requires a lot of lube to run, e.g. phosphorus BCG, I tried a PRI gas buster CH, and it did definitely make a difference. Not so much when I changed over to NiB. On another note, an acquaintance of mine was using the P-Tex method in his CH on a SBR with a can, and it just blew out in chunks, after a magazine or two, they may want to go the route that GD did.

I realize that wasn't Gator's point, he's dealing with a weapon with a can, but someone reading this, who has to keep their weapon well lubed, especially in dirt/dust conditions, might benefit from it.

FT

[gatordev]

Nice to hear someone else with a review on one of these. I know Roy at WO is pretty high on them, but admitted they don't work well for left handed shooters like me. I guess I'll just have to resign myself to gas in the face whenever shooting the AR platform.

If I was left-handed (with a conventional upper), I'd rather run the gun without the Gas Vent than with it. At least for my gun today, the gassing seemed a little less running it conventionally than running it with the vent (when shooting weak-handed). But again, I want to run it longer before I completely pass judgement on it.

UWone, you're problem is that we see all those uppers you have, you just need to break down and get a left-handed upper for your suppressed guns. Then you could run this and see how it works for you. Or just learn how to shoot like normal people do. Either way.

[UWone77]

If I was left-handed (with a conventional upper), I'd rather run the gun without the Gas Vent than with it. At least for my gun today, the gassing seemed a little less running it conventionally than running it with the vent (when shooting weak-handed). But again, I want to run it longer before I completely pass judgement on it.

UWone, you're problem is that we see all those uppers you have, you just need to break down and get a left-handed upper for your suppressed guns. Then you could run this and see how it works for you. Or just learn how to shoot like normal people do. Either way.

gator,

Once in a blue moon I think about getting a left handed upper, but ultimately I always decide that it's not worth it for all the proprietary parts. Besides other than Stag who else is making a left handed upper right now? I haven't done any searches in awhile.

In the end, I think I will probably see what a long stroke piston system will do for me on a dedicated suppressed set up. I've already ruled out the short stroke system as Adams Arms kits have not been kind to me the last 2 times I built an upper around them.

Until then, the quest for less gas in the face remains.

[gatordev]

Makes sense. To be honest, I don't really know what's out there for lefties, but I couldn't resist pointing out that it's an upper you don't have, which is no small feat...

I'm actually very interested in trying a suppressor on a piston gun for comparison. I don't pray at the alter of piston guns, but I've had very good luck with my Mega branded AA piston kit, functionally, so it would be interesting to see how it does suppressed.



It's since gone on a diet with a T-1 and a B5 SOPMOD. It's probably got ~1300 rounds with no signs of tilt. I need to pop off the BattleComp and put on a SF break so I can test it out.

[UWone77]

Never really felt the need for a left handed upper until I started shooting a dedicated suppressed upper on a FA Lower. I find that the gas isn't "that bad" when shooting controlled strings. I also have switchblock uppers to help mitigate some of that extra gas. I also have a couple of 300 BLK uppers that won't cycle without a can, so that also helps with the gas. However, I don't like uppers that won't shoot without a can. Sometimes they need to be tuned a bit to get working "reliably" and I do use that term very loosely. In the end, there is no free lunch I guess, so I guess I'll have to someday put that LH upper on the list.

Speaking of uppers I don't have...

Nice Mono Upper! I had 2 Midlength ones that I got rid of and kind of regret it now.

[gatordev]

Nice Mono Upper! I had 2 Midlength ones that I got rid of and kind of regret it now.

Thanks. That was my first SBR and first build from scratch. In hind sight, your ergos are locked into whatever length of handguard you buy with it, and I wish I had more real estate with a 11.5" gun, but I can't see myself selling the upper just because they're not around anymore. Plus the gun still shoots fine, which is probably the most important part.

[gatordev]

So I ran a little test today with my above pictured piston gun and my can. I wasn't able to do a whole lot because by the time I had it rezeroed (after putting a new muzzle device on it), a group had come over to the bay I was using and I couldn't be downrange and working the targets as much. However, I ran a couple of boxes of ammo through the gun while running on the suppressed setting. First of all, with a H2 buffer and on the suppressed setting, I was blown away with how smooth the thing was. Despite it having an Op Rod, it would push only slightly more than a .22. I can understand why people that tune their guns with adjustable gas blocks do it if they're trying to shave every last hundredth of a second off for competition. Again, because of time, I didn't have time to quantify the reduced recoil (I only had non-suppressed times to work with and couldn't use my timer with the new group showing up), but it felt pretty handy shooting it, albeit heavier with the can at the end.

As for blow back...here's what I saw...

I was initially doing some drills with my M4 Block 2 clone, mostly unsuppressed, but then suppressed. While I might get a whiff of something every so often, even after hammer pairs, blow back wasn't an issue. Switching to the op rod gun suppressed, I was still getting some blow back, but not as bad as my MK18 and better than my 12.5 DI upper, but still there. Unfortunately it's not an apples to apples comparison since the MK18 is 10.3", the piston gun is 11.5" and the other gun is 12.5", but at least it's data. How valuable the data is is up to you.

One last bit of interesting data... After zeroing the gun with a non-cold bore, putting the suppressor on moved the POI up (!) about .5-ish MOA. Wasn't expecting that, but I'll take it. No windage adjustments needed, just up at 12 o'clock. I've found that every gun so far after putting on the Surefire can changes the POI in the vertical axis and not the lateral one. I'm certainly happy with that.

[gatordev]

More data on the gas vent today with my MK18. Initially there was a very slight breeze from the right to the left. As such, I found that I was getting what felt like at least as much gas from the AR vent as would have occurred without it. Obviously the wind was the variable, but it kind of soured me on the vent. After a few sweaty minutes later, the wind pretty much died and I would still get some gas. I did one test where I advanced on the target while quickly firing at some steel for 10 or so rounds. At the end I had to spit the taste of gas out.

I'm sure it's doing something, but I'm starting to wonder if it really matters at the end of the day. If I shoot weak (left) handed, I still have to contend with the ejection port, and with the vent, I get another face full of gas. I may just put the FA back in the gun and run that a bit and see if I notice a difference. So far I've probably run ~500 rounds suppressed without the vent and about 300 with it. I guess at this point, I'm kinda meh.

[UWone77]

Thanks for the update gator. Basically, it just shows you the gas has to go somewhere, into my face is about it.

My next thing might be to use a LMT Enhanced carrier.

[gatordev]

My next thing might be to use a LMT Enhanced carrier.

But then you/I have to buy yet another part at a premium price while my existing pile of parts works perfectly fine. I'm thinking the next step, mostly out of curiosity, is to try some RTV on the charging handle. Cheap and even if it doesn't do anything, I'm still very happy with my rifle as is.

[tact]

Well that's disappointing. I thought I saw someone using that gas vent on a Leonidas build and they reported favorable results, but then again it was an integrally suppressed 300 so perhaps that was a factor.

[gatordev]

To be clear, it is doing something, but I'm not convinced it's doing enough at the expense of how I may use my rifle. Shooting weak handed isn't an everyday occurrence, but I do like to practice it and occasionally need it if I shoot in a competition. Between that and the fact I was getting gas from a breeze, I'm leaning back to a regular FA...which I just put back on about an hour ago. Really, the biggest issue with gas I've had was this particular rifle since it's only a 10.3 barrel.

Maybe after I run it a little more with the FA back on, I'll change my mind. Either way, I need to get some sealant and try that.