Getting Ar15 adjustable gas block from US

Hi guys. Going to put a DPT on my Ar. Looking to get an adjustable gas block so I don't have lots of gas back like i did in my last suppressed AR.
Looking at a Syrac low profile block for $99 at brownells.
Was wondering if this will be a simple task with the whole ITAR crap?, read somewhere items must be less than $100us then their is a one off $49 fee, is inspected my govt before shipping etc etc etc. Is this the case?
Alternatively I have a mate over there I could send it to then he resend it on to me.

Henry

Syrac wasn't approved for export last time I checked.

Sent from my XT535

Syrac is no go as above. $100 is the limit before you need to fill out paperwork for the dept of state. No other fees. JP and PRI blocks are good to go.

Are adjustable gas blocks needed for suppressed AR goodness?
Suppression is on my to-do list.

Not needed but help. where do you go to find what brands/ products are able to be exported?

Just go to gunworks and Robbie will put an adjustable screw in your gas block which does the same thing, had mine done for $30

..

Quote:

---

Originally Posted by mcche171

Not needed but help. where do you go to find what brands/ products are able to be exported?

---

https://docs.google.com/spreadsheet/...aY3dzcUE#gid=0

That sounds a lot easier. Does the position of the screw shift with firing?

Not that I have found,I loctited my first two but my latest one (jp low profile) I never got around to it-nearly 2000 rounds later and it's still staying put

Res do you have a proper gas block or one that robbie has put together?

Quote:

---

Originally Posted by mcche171

Res do you have a proper gas block or one that robbie has put together?

---

I have both, but the one I was talking about is a JP brand unit from brownalls

http://www.brownells.com/rifle-parts...%20ENTERPRISES

Attachment 25028

You can't go past JP stuff, bloody good kit. How do you find the one Robbie put together?

Works fine,it fixed the issue of over gassing that came about when he fitted a can about ten years ago. He adjusted it the and I have never touched it since. That said i have not used that upper much in the last few years and I'm guessing it's only seem 700ish rounds. I should sell it but I won't

Might have to give Robbie a call tomorrow.

If you have a drill,a tap and a grub screw it's no big deal to do yourself.

But if your close to him and he's only asking $30.....

I wonder if there is enough meat to drill into a low pro gas block. Does the grub screw go into the tube through the block?

Not into the tube itself (the tube is a consumable remember) into the area before the tube to limit the gas entering the tube.
Some aftermarket barrels have smaller gas holes than others so effectively all ready do this-I have a true flight barrel that has a tiny hole so doesn't really need an adjustable block. The cheeper the gun the more likely it is to have a large hole to make it more reliable-these old guns that no one ever thought were going to get suppressed are why everyone now thinks they need an adjustable block if they are fitting a can.

Quote:

---

Originally Posted by res

Some aftermarket barrels have smaller gas holes than others so effectively all ready do this-I have a true flight barrel that has a tiny hole so doesn't really need an adjustable block. The cheeper the gun the more likely it is to have a large hole to make it more reliable-these old guns that no one ever thought were going to get suppressed are why everyone now thinks they need an adjustable block if they are fitting a can.

---

I have to disagree. If the gun cycles at all unsuppressed, then it's going to be overgased when suppressed.

More gas than needed to make something just work does not make it automatically over gassed.
Not all ar's are race guns tuned to within an inch of its life. A lot of modern cans also don't cause anywhere near the extra back pressure that older cans did as another factor.

The truflight barrel I was talking about is not reliable with all ammo without a can btw.

Over gases is a over talked and thought subject for a lot of modern guns unless your moving into short gas systems.

From your pics you have barrels that are designed for military applications so they will probably have a largish gas hole to ensure function with almost any ammo and a dirty gun. So yes I can see why you find it important

At the end of the day an adjustable block puts one more thing to go wrong on the gun,but it rairly does so for my use I run them-even tho I no longer think I need them on most of my rifles.

OSS claims that suppressors from 'industry leaders' (in the states) increase bolt velocity by 28 to 44 percent. A 44% increase in bolt velocity is over 100% increase in kinetic energy. An AR that just barely cycled unsuppressed would suddenly cycle with over twice the energy it needs. In other words the bcg/buffer would slam into the back of the extension with as much energy as if you shot a correctly gassed AR with no buffer spring in it.
Even a 28% increase in bolt velocity equals a 64% increase in Ek. Like you said, gas ports are generally slightly larger than needed to ensure reliability, so taking that extra energy into account, a 64% increase on top of that isn't exactly a small increase that should be ignored.

I'm not sure who OSS are,but it's interesting to see numbers rather than just observations.

Not sure what those number = in the real world.

I personally have always thought of over gassed as being when there are problems showing up, eg marks in the receiver/extension or the action getting dirty at an excessive rate(and that is subjective as everyone has different tolerance to cleaning) or the bolt not picking up rounds due to excessive speed. In a race gun I have used an adjustable block to try to keep the gun as still as posable while it cycles-to enable more accurate double taps,light weight carriers were part of that as well. Stoping excessive gas in your eyes is another plus but I find a moded charging handle helps a lot more with this.

Personally never seen an extension more than marked from the buffer,so to me it's not that big a deal.

Part of my thinking as to why people can be to gas block happy is a lot of people set them up so things only just work with one sort of ammo and then something changed-eg ammo,temperature,altitude or cleanliness of the gun and they start having problems. This is why makers run more gas than they need by a big margin,and it's why on my rifles
I set them up so that I'm risking being slightly over gased rather than slightly under gased.

I hope it does not come across as trying to argue with you about it,it's just interesting to talk about-and as I have said I run adjustable blocks on most of my rifles.

Operator Suppressor Systems Oss Operators Suppressor Systems - Silencers
They make suppressors with a turbine type system instead of baffles.

When I say over gassing, I'm meaning past the margin for reliability. You should definitely have more gas than the minimum required for cycling to have a margin of reliability, but a suppressor will often greatly exceed this margin, even on an already lowly gassed gun. It's not like over gassing by an extreme amount will ensure better reliability in adverse conditions. The action spring will be the weak link and will fail to return the bolt in to battery, making all that excessive energy that ensured full rearward bolt travel fairly redundant.
Then there are all the negative effects of increased bolt velocity. More blowback, increased wear, higher chance of malfunctions, increased felt recoil, rougher extraction. Even if a gun cycles without issue when over gassed, it will still develop malfunctions sooner than if it wasn't.

The way I look at it is, gas dwell time and gas port diameter on a gun have been tuned to one another to ensure correct cycling. If you change one, you need adjust the other. Screwing a suppressor on the end completely changes dwell time and the depressurization of the barrel. The gun is no longer functioning as designed and in a less than optimal state. I can't think of any reasons to purposely leave a gun excessively over gassed, but I can think of plenty of reasons to tune it down.

It almost sounds like we are setting things up the same,just starting the conversation from dif ends of the possibilities .

Spiral cans? Like a de sail .45-that's cool