Is it worth the extra money for an ajustable gas nut, or adjustable gas block?

AR-15 » AR Discussions

AR Sponsor:

Site Notices

[ARCHIVED THREAD] - Is it worth the extra money for an ajustable gas nut, or adjustable gas block?

Posted: 7/30/2005 2:51:04 PM EDT

Just wondering how worthwhile these products are: adjustable gas nut, adjustable gas block. (gas block like the one sold by JP Enterprises.) Thank you for any opinions.

Posted: 7/30/2005 10:15:45 PM EDT

[#1]

Depends, what are you going to use the rifle for? Are you planning on using any really light or heavy loads? Having cycling problems? Using a suppressor?

Posted: 7/31/2005 3:44:06 AM EDT

[#2]

No, just normal use- mostly target shooting and maybe competition. I was just reading more about the JP Enterprises gas block. One person found it very difficult to install.

Posted: 8/22/2005 6:59:21 PM EDT

[#3]

Are there any more information or opinions on this subject? I am thinking about adding one of the JP Enterprises adjustable gas blocks on my new (actually first) AR.

Thanks.

Posted: 8/22/2005 10:34:23 PM EDT

[#4]

Quoted:
Are there any more information or opinions on this subject? I am thinking about adding one of the JP Enterprises adjustable gas blocks on my new (actually first) AR.

Thanks.

My opinion is "if it aint broke, don't break it"

If I don't have any reliability problems with my AR, I do not want to add one more component to its mechanism, because that is one more piece that can break.

Like others said, if you are PLANNING on using heavy (or unusual loads) then it might be worth it, but for regular use I really don't see the purpose. Plus, would the highest (i.e. most "open") setting on an adjustable port really give "more" gas than a regular (non-adjustable) system - or would the highest setting simply be equal to a normal unadjusted AR? If that was the case, then the ONLY purpose would seem to be if you are shooting specially loaded ammo.

I dunno - the gas system seems to work remarkably well on the AR platform, I really don't think an adjustable gas port is necessary. How dirty woudl an AR have to get before one would need to increase the gas pressure??

Posted: 8/22/2005 10:50:25 PM EDT

[#5]

I'll backup DK on this one as well.
With a typical AR chambered in 5.56, there is not much need for an adjustable gas system unless your gas port is oversized.
You can't buy very many loads that would NOT work with a normal gas setup.

That said, I sell a LOT of JP gas blocks on 300x221 uppers that I build.
Here you need it to recognize the full potential of the barrel.
The JP block does use a setscrew to adjust gas flow and there is no mechanical lock to keep the setscrew adjusted.
I usually use loctite and I have had good luck so far.

If your rifle works as it is, just leave it alone.
Got money to burn?
Buy a copy of Jim Crews training CD and then MORE AMMO!

www.marksmans.com/sys-tmpl/carbinetrainingmanual/

Randall Rausch
www.ar15barrels.com

Posted: 8/22/2005 11:01:09 PM EDT

[#6]

+1 to all that was said before, good to know there are some smart people left here.

a standard AR with standard loads doesn't need an adjustable anything.

Posted: 8/22/2005 11:10:55 PM EDT

[#7]

Unless you are doing a wildcat like .300 whisper or something dont mess with a 100% functional design. Ask your self WHY AM I DOING THIS and if the answer is I HAVE NO IDEA then dont do it.

Posted: 8/22/2005 11:19:52 PM EDT

[#8]

Quoted:
+1 to all that was said before, good to know there are some smart people left here.

Where? Where are the smart people?
I don't see any...

Randall

Posted: 8/23/2005 12:57:28 AM EDT

[#9]

Or you can have Randall chamber a tack-driving, full bull, super match barrel for you and then you will have a legit excuse to get the gas block.

Posted: 8/23/2005 2:37:42 AM EDT

[#10]

Quoted:
No, just normal use- mostly target shooting and maybe competition.

It is not needed for what you intend to use your rifle for.

Posted: 8/23/2005 4:20:17 AM EDT

[#11]

what everyone has stated already

Posted: 8/23/2005 5:44:07 AM EDT

[#12]

Thanks for the input guys.

Posted: 8/23/2005 12:26:00 PM EDT

[#13]

Oddly enough (unless you know me), you guys are making me want one now...

Posted: 8/23/2005 1:39:30 PM EDT

[#14]

I'm running an MGI adjustable gas tube on my M16, but my reasoning is two-fold. First, I'm using an MGI rate/recoil reducing buffer, and with the adjustable gas tube, I can cut the gas flow down to the bare minimum required to lock the bolt back on an empty mag. This allows no more recoil than necessary. Second, over time my M16's gas port will erode, leading to more violent cycling. I can meter my gas flow down as the gas port's diameter increases to avoid this situation.

Posted: 8/23/2005 1:45:32 PM EDT

[#15]

Quoted:
I'm running an MGI adjustable gas tube on my M16, but my reasoning is two-fold. First, I'm using an MGI rate/recoil reducing buffer, and with the adjustable gas tube, I can cut the gas flow down to the bare minimum required to lock the bolt back on an empty mag. This allows no more recoil than necessary. Second, over time my M16's gas port will erode, leading to more violent cycling. I can meter my gas flow down as the gas port's diameter increases to avoid this situation.

For that kind of specific application, it makes perfect sense.

As an aside - how much does it take (rounds) to erode/expand a gas port to the extent where it actually makes a noticable difference?

Does it happen around the same time a barrel starts to get worn out anyway (rifling, throat erosion) or can it happen long before?

Posted: 8/23/2005 2:00:30 PM EDT

[#16]

Quoted:
As an aside - how much does it take (rounds) to erode/expand a gas port to the extent where it actually makes a noticable difference?

I was told by Tom at MGI (posts here under the screen name "twl") that after 1-1.5K rounds, the gas port has eroded enough that it is noticeable.

Posted: 8/23/2005 5:19:53 PM EDT

[#17]

Quoted:
Quoted:
As an aside - how much does it take (rounds) to erode/expand a gas port to the extent where it actually makes a noticable difference?

I was told by Tom at MGI (posts here under the screen name "twl") that after 1-1.5K rounds, the gas port has eroded enough that it is noticeable.

Really

I did not expect the number to be so low!

Wow. If that's the case, maybe an adjustable gas system isn't a bad idea for those who shoot their ARs a lot - just to compensate for that erosion.

Posted: 8/23/2005 7:48:03 PM EDT

[#18]

That's terrible. Only 1500 rounds and the gas port is opened up to make a difference? Crap design if you ask me, first it shits where it feeds, and the gas port deal.

Posted: 8/23/2005 9:08:15 PM EDT

[#19]

Well, I haven't really noticed but I haven't looked for it. I've shot thousands and thousands of rounds without any change in functioning.

Posted: 8/23/2005 11:24:46 PM EDT

[#20]

considering that factory ports vary considerably I think the better question is how much gas port erosion is too much. if it's important (and not just marketing) it's odd that Sam checks the throat erosion but doesn't have a gas port erosion gage.

Posted: 8/24/2005 12:29:25 AM EDT

[#21]

So true, you would think they would simply all be cut to spec but they are not. Many people have to fool with the gas port size just to get their shorties to run.

So I am curious, if the gas port is to spec, how long till reliable function is lost in terms of round count and how does this compare to average barrel life?

Posted: 8/24/2005 2:23:32 PM EDT

[#22]

Quoted:
So I am curious, if the gas port is to spec, how long till reliable function is lost in terms of round count and how does this compare to average barrel life?

I don't think that it is so much a loss of reliable functioning as it is a more violent cycling. I guess that the more gas you get, the harder it cycles.

Posted: 8/24/2005 2:34:27 PM EDT

[#23]

Well if you get it to barely cycle what happens in cold, muddy conditions? Your rifle quits working thats what. Leave room for fouling and nasty conditions. Wait if you did that you would be back to where you started. Back to no reason for an adjustbale gas tube again.

Posted: 8/24/2005 2:45:32 PM EDT

[#24]

David(M4madness) did a good job of explaing the reasons.

It is primarily used for 3 different purposes.

The first is to compensate for erosion of the gas port over time, which is very common in carbines because of the high pressures involved in the shorter gas system.
The metering is set by the gas port diameter, and if/when this diameter increases via erosion, then the metering is no longer correct.
The adjustable gas system allows the user to restore correct metering of his gas system when erosion has occured in his gas port.
This can keep cycling speeds minimized, reduce battering, reduce felt recoil, and generally have a positive effect on reliability, when used properly.

Secondly, it is used when other cartridges are used in the AR15 which have different gas pressure curves than the 5.56. The user can set his metering with a unit that is adjustable.

Thirdly, it is common for cycling to be much higher when using a suppressor on the barrel. An adjustable gas system allows the user to adjust for this change, and re-adjust when not using the suppressor.

Regariding the comments about not needing it, to each his own.

Regarding the comments about cycling problems if you adjust it too small, we recommend having the adjustment slightly more open than the minumum, to acommodate load variations and temperature changes. If it becomes apparent that something has changed enough to cause a problem, you can open it up some more.

It's just like anything else that is adjustable. Some people can learn to use it to their advantage, and others can't, or won't. It is up to the individual to decide if it is something for them, or not.

We're not pushing it down anybody's throat.
We're just making it available to those who want it for their own reasons.

Posted: 8/24/2005 2:55:06 PM EDT

[#25]

Quoted:
That's terrible. Only 1500 rounds and the gas port is opened up to make a difference? Crap design if you ask me, first it shits where it feeds, and the gas port deal.

What is it going to do? Catch disentery from itself?

It does not shit as it is not a biological organism.