Short Stroking ATRS MS build

QuickDraw16

QuickDraw16

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I finally got out to try my Modern Sporter and wasn't able to get it to eject spent cases.

When fired the BCG moves back by 0.25 - 0.5" (see video below)

There are no obvious signs that the cases are being caught in the chamber. The bolt moves freely when pulled with the charging handle.

It has a standard buffer from and spring.
The gas block is not adjustable. Found here https://truenortharms.com/ar15_default_store_view/ergo-adjustable-gas-block-0-76.html

Assembled by the handsom man in the blue shirt shown in the video.

This must be either a case of under-gas or a buffer weight issue, right?
Any tips on how to troubleshoot this would be appreciated!

 
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1 Lubrication of the bolt assembly
2 Gas delivery insufficient
3 Rough chamber in barrel precluding easy extraction.

Try the list in order as see what happens.
 
Mine was short stoking too. But my bcg was moving the full length to the rear. Ended up being an out of spec buffer tube. The tolerance on the MS are tighter than an Ar. The bolt doesn’t travel as far to the rear as an Ar because by design the actual receiver is shorter. Ended up mine was a buffer tube issue. I just replaced it with a new one and solved the problem. However yours sounds like a gas issue. Also run the bcg wet. Mine works 100% now.
 
Likely a gas issue, it's very easy to misalign the gas block when assembling an upper.

If you're using an adjustable gas block, make sure it isn't in a super closed position.
 
Worth asking, was this rifle assembled by yourself, bubbas basement gunsmithing friend, or a qualified gunsmith/armorer?

What gas block is used? Standard or adjustable?

Buffer springs/weights used?

Give us as many specifications as you can, more info = more detailed answers.
 
I had cycling issues with my sporter, turned out being an undersized gas port in the barrel. Was an easy fix with the right drill bits, works like a charm now.
 
Fairly obviously a gas problem. Either the port is too small on the barrel, port doesn't line up with the gas block (for whatever reason), or there's an obstruction somewhere in the gas system. Or it's dumping gas somewhere it shouldn't.
 
Scotty454 said:
Fairly obviously a gas problem. Either the port is too small on the barrel, port doesn't line up with the gas block (for whatever reason), or there's an obstruction somewhere in the gas system. Or it's dumping gas somewhere it shouldn't.
Click to expand...

What size should the gas port be?

Edit: used my google-fu
 
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What brand barrel? Can plug the barrel and blow air down the muzzle end and listen for gas flow as you adjust the gas block to ensure best alignment
 
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