Need an AGT

[Stephen J.]

So, I've been fiddling around with my 300 Whisper AR carbine with Carbine gas port. Mainly trying to get the Subs to cycle the action. I've put the rifle stock back on with the carbine spring and removed all of the weights from the buffer. It seems like I've heard here that slower powder can help. I had some 2400 on hand so I tried it. It Cycled about as well as H110 with no modifications to the spring and buffer. Eject but not strip the next round. This weekend I'm going to go back to the H110 with the shorter spring and lightened buffer and see if it cycles. I've been looking into my options to get it to cycle, I was looking at the AGT but Fulton doesn't sell it anymore. Did they manufacture it or does someone else? What are my options in the way of adjustable gas blocks. I'd like one with at least top and bottom rails. Your suggestions would be appreciated.
Stephen

p.s. in case you are wondering, no it is not going to be suppressed.

[Spook]

you might try AA 1680 @ 10.3 grains with a 220 grain bullet.

[Flewis]

First make sure your gas port is opened up to 0.125. Mark the exact location of the gas block and then take it off (the gas tube should be pinned to it and comes off with it). If you've shot it much you should be able to tell if the alignment was ok from the powder ring around the port. Measure the port diameter. Next make sure the tube in the gas block is aligned properly. I had one that had been pinned in place with about 1mm of the tube obscuring the hole in the gas block and it was keeping the rifle from cycling. A little drill work fixed that.

I tried all the tricks and couldn't get H110 to cycle my rifle (16" barrel, carbine position port). 11.6 grains of AA-1680 behind a SMK 220 cycles it flawlessly with the stock buffer and spring. I also use 11.0 gn of 1680 behind a Hornady 208 grain AMax. Both are subsonic loads for me.

[kdiver58]

An ATG will not help you with sub sonic rounds. They are only for cranking down on the gas when shooting full power ammo.
Both of the above posts are spot on. I found I had to match the burn rate of the powder to the bullet ...And 1680 is the powder.
Mine cycles , locks the bolt back and the rounds are subsonic.

http://www.youtube.com/watch?v=ilNf6OiHd5c

[interceptor]

<-- carbine gas system, 88 gram buffer, 220g SMK, 11.8g AA1680. functions 100% for me.

HOWEVER.... Tried my loads in a friends AR .300 last night and they are supersonic. Go figure.

I think I'm about to go back to the drawing board though. My form 1 came back today and I will bo chopping the barrel down to 9.5" and going to a pistol length port. Oh well, I guess I had too much free time anyway...

[Stephen J.]

So, I finally found some time and loaded up 3 220SMKs with 8.0 grains of H110. Rifle Stock, Carbine spring and lightened buffer. Fired all three rounds with no problem. It didn't lock the bolt at the end but that was the only problem. Not sure what my velocity is since I still don't have a chrony but my extra set of ears said there was no ballistic crack so it appeared to be sub sonic. KDIVER, in using an AGT I would have bored out the gas port until I got it to cycle. Then used the AGT to cut down on the gas for the full power loads. I guess I better get some 1680 because I would like the bolt to lock back and I would like to have my collapsible stock back on.

Stephen

[kdiver58]

I would highly recomend a adjustable gas block instead of a tube. I bought a tube and it was a loose piece of junk. I had to make a new metering screw for it. The set screw that came with it was too loose.
Noveske is building gas blocks and I'm going to buy one of his as soon as they are available.

Good luck.. My M1S upper came with a .120 gas port

[mooster1223]

Here ya go. It's even in stock. http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=396319

Jim