Modern Sporter - Build Discussions

PinaKaleada said:
Since both of you have TNA gas tube... I wonder if the tube seals gas enough at the gas key interface.
Click to expand...

This is something I never thought of. As a test I took everything (firing pin, cam pin and bolt) off the BCG. When I slide it forward into the upper receiver and onto the gas tube there is no extra resistance when the gas tube begins to slide into the gas key. Is this normal?
Also though maybe checking the length the tube protrudes into the receiver might be a good idea so I took this picture:
Gas-Tube-In-Reciever.jpg

Does the length look correct?

EDIT: I also note that there is a lot of carbon on the gas tube closest to the front of the receiver, but very little where it would be inside the gas key. Is this normal?
 
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I had the same issue with the bolt carrier being caught on the bolt catch. I replaced the buffer tube with an enhanced one so that I could unthread it a couple turns while still being able to retain the detent. Before I changed the buffer tube, when I pulled the bolt back with the charging handle there was only about a 1/8” gap between the catch and bolt face. With the new tube threaded out a bit, I’m getting about 1/4”+. I think that made all the difference.

Like others suggested, try a better quality GB and make sure it is perfectly aligned.

I think the wear on the top of the lower receiver caused from the charging handle is normal for a MS. All of mine have it as well, I’m using radian and Geissele handles.
 
greg olmstead said:
Gas system and buffer tube length have nothing in common. Don't get caught up on carbine and rifle.

A carbine buffer tube is the length of the buffer tube and usually uses and adjustable stock of some kind. Rifle length buffer tubes dont use adjustable stocks and are smooth. The stock bolts to the tube at the back of it and is used for stocks like the a2 or fixed stocks.

Rifle length gas system is a term for how far away the gas port is from the upper. Same as carbine, mid length and pistol length. And to really screw with things someone invented an intermediate lenght and a rifle plus 1 or 2 or 3" system.

Rifle length gas systems are usually found on barrels longer than 16 inches. Carbine length is for barrels shorter than that. Midlength even shorter and pistol is the shortest.

A longer gas system increases the time the case spends in the chamber after the bullet leaves the muzzle. Shorter systems decrease this and if the system is to short the rifle will try to extract the case before the brass has contracted enough to allow it to extract.

Buffer weights can be switched out to "time" the rifle without using and adjustablegas block. If your rifle is over gassed with a carbine weight you go up to h1 weight. Timing is the ejection pattern of the cases. 3-4 o'clock is properly gassed.

I should add that carbine and rifle length buffers are differnt too. The rifle length tube needs a longer buffer to stop the BCG from hitting the buffer tube. You can't use a rifle length buffer in a carbine tube and you can't use a carbine length buffer in a rifle length tube. These are the only rifle and carbine things that need to match.

If you have a rifle length buffer and buffer tube use it on your MS with the proper buffer and put that 18.6" barrel on the with the rifle length gas system and shoot away. Same goes for a carbine buffer tube and buffer.

The gas system has NO correlation to your buffer tube
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Thanks Greg O.
Got that loud and clear. I truly appreciate you taking the time to explain. Will fit carbine tube, spring and buffer assemblies already on hand "as is". Only if the ejection pattern hints toward timing issues, then I will consider buffer weight adjustment.
Now just waiting on ATRS to deliver the magic bits. With luck it will be under the tree for Xmas.
 
Hello Everyone,
I just wanted to write to thank everyone who gave me input on the Modern Sporter issue I was having and posted about a couple weeks back. Based on the feedback I received I replaced my aluminum gas block and the gas tube installed in it with a new MRA Pincer Gas Block and a gas tube from them. This resolved the issue completely. After a few boxes of various ammo I had zero failures to feed or fire and zero failures to lock open on the last round. I even fired about 10 rounds loaded individually (one per mag) into my magazines and all held open. The brass is also ejecting at 3-4 o'clock now versus 4-5 o'clock now indicating more gas. I am very happy and cannot thank everyone enough for the input. Thank you everyone for the help, ATRS for the wonderful receiver and all the best!
 
SouthSurrey45 said:
Anyone know where they’re at with orders currently ?
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I got this message back in September last time I asked...

I would currently anticipate sometime around the end of December for your order, but hopefully a little sooner.

We have a bunch of FA uppers at anodizing right now, SHOULD be enough to clear out the 2019 orders from October, November, December and hopefully all of the 2020 January orders as well.
I think we should have those back in a week and a half or two weeks.

Cheers,
Shaun
 
twinge6805 said:
Hello Everyone,
I just wanted to write to thank everyone who gave me input on the Modern Sporter issue I was having and posted about a couple weeks back. Based on the feedback I received I replaced my aluminum gas block and the gas tube installed in it with a new MRA Pincer Gas Block and a gas tube from them. This resolved the issue completely. After a few boxes of various ammo I had zero failures to feed or fire and zero failures to lock open on the last round. I even fired about 10 rounds loaded individually (one per mag) into my magazines and all held open. The brass is also ejecting at 3-4 o'clock now versus 4-5 o'clock now indicating more gas. I am very happy and cannot thank everyone enough for the input. Thank you everyone for the help, ATRS for the wonderful receiver and all the best!
Click to expand...

Good for you!!
 
Hi colin, thanks for this reply, i'm not able to make my ms cycle proprely, i tried a lot pieces to fix the issue but i didnt try another buffer tube, it's very frustrating man, hope it will fix my gun, thanks!
 
ColinD said:
I had the same issue with the bolt carrier being caught on the bolt catch. I replaced the buffer tube with an enhanced one so that I could unthread it a couple turns while still being able to retain the detent. Before I changed the buffer tube, when I pulled the bolt back with the charging handle there was only about a 1/8” gap between the catch and bolt face. With the new tube threaded out a bit, I’m getting about 1/4”+. I think that made all the difference.

Like others suggested, try a better quality GB and make sure it is perfectly aligned.

I think the wear on the top of the lower receiver caused from the charging handle is normal for a MS. All of mine have it as well, I’m using radian and Geissele handles.
Click to expand...



Hi colin, thanks for this reply, i'm not able to make my ms cycle proprely, i tried a lot pieces to fix the issue but i didnt try another buffer tube, it's very frustrating man, hope it will fix my gun, thanks!
 
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