300W Gas port size with 20" barrel

[txjm]

All the discussions I have found on port sizes refer to sbr, pistol and carbine port locations. Most of those are subsonic applications. I am having a problem trying to get a 20" barrel running with supersonics. My port size is .096". The port location is in a normal rifle position. My barrel is a Remington take off that I rechambered to something similiar to what others refer to as a 7.62x40. The closest to ejecting brass I have come is for the brass to jam in the port as the bolt closes. I am running about 2250 fps with A1680 and a 125G BT. I am scared that I should have put the port in the carbine location. I have only taken it to the range once. When I removed the gas block the port seemed to be a little clogged?? What is the best way to ensure the port lines up with the hole in the gas block? I am using a EGW clamp on gas block.
This seems to be a great forum. I am very enthusiastic about the whispers. I have a contender 10" 300w, a 1.5" 284W wildcat that I shoot 200G lead out of and this ar. They are all a blast.
Thanks

I notice I am probably on the wrong forum. Move if you want to. I will do better next time.

[kurtz]

welcome to the world of trying to get a rifle length system to run :smile:....

to get the rifle length 7.62x40 to run I had the best luck with 125 flat base bullets (TNT, Pro-Hunter, etc...), more than 25gr of A1680, and a gas port between .104 and .107"....there are a couple other make run tricks like: reduce mag stack pressure (drags on the BCG), play with buffer spring tension and length, and reduce buffer weight.....

the 20" rifle length gas system is now one of my favorites after I got it to run....very smooth and highest velocities I have been able to achieve with the 125 TNT (over 2,600 fps)....building a 20" Noveske 7.62x40 rifle length gas system this weekend....

good luck,

hope this helps,

kurtz

[txjm]

I will take the port out a little more. I have some flat base Sierras on the way. I tried it this weekend with H110 and NBT's. I tried my A2 butt stock and my CAR butt stock. I haven't been successful yet. How do I change the buffer weight? Cross drill?? Bore?? Are rifle lighter than carbine? It is nice to know that I am not alone. I did push 2500 this weekend, pretty flat primers!
Thanks

[kurtz]

If you can lay your hands on some Accurate 1680 powder I think you'll be happy with the results over the H110....the 1680 has a longer pressure curve which helps with cycling issues found with the more abrupt H110....the primer flattening should go away also....

the only buffer mods I have done is to drive the roll pin out, open the buffer and remove or add weight to see how it changed the cycling.....with the charge I'm running now I ended up being able to use a full weight rifle buffer....loads at or under 25gr of 1680 with a 125TNT I had to run a reduced weight buffer....

hope this helps,

[txjm]

I played with a little 1680. I ran out fire forming brass and have more on order. I was up to about 23G and started seeing pretty flat primers with the 125G noslers. I hope I can bump it up a little with the flat base sierras.
I opened the port up tonight. maybe that, different bullets and 1680 will do the trick. 22.5G of 1680 with the noslers would open the bolt enough for the case to hang in the ejection port, everything else either closed or hung on the edge of the barrel extension.
Thanks
Chip