Bolt catching on bolt catch .

[bigdaddyjak]

[montana]

The bolt catch should not touch your extractor..The bolt catch will catch the lower two bolt lugs.. Your barrel is .0938 and Lilja 20" barrel specs out at .093, so your gas port seems just right. I would check your gas key, gas block, etc for gas leakage.. What bolt carrier group do you have?? All bolt carriers are not made the same. The bolt tail vs the firing pin chamber dimensions can create gas leakage, if the differences in diameters are great..Did you check your gas tube button with a gauge?? Is the gas tube cracked?? There could be friction "binding" in the lower receiver buffer tube, off center barrel extension, leaking gas block, gas key, under power ammunition,ruff or short chamber or throat, etc..

[montana]

You should also check your gas rings..

[bigdaddyjak]

[montana]

Did you do the common gas ring test by extending the bolt from the carrier and setting it on a flat surface to make sure the gas rings hold the bolt up?? Drilling out a gas port is the last thing I would do.. There are so many other variables to check, "before I would increase the gas port size" especially when your gas port seems to have specked out perfectly.... Gas keys can leak, "with no outward sign" until they are removed.. The gas tube and gas block fit can leak excessively..Gas tube button and gas key I.D. can be excessive, creating less gas efficiency..Gas block may not be mated to the gas port 100% by being too far forward, too far back or cocked sideways.. The 3 bolt carrier well "chamber" sizes can be extreme, causing gas inefficacy.. The combination of many factors can cause under gassing, that can be fixed relatively easier than drilling out the gas port.. Adjustable gas blocks, "can only lower the gas pressure" of the drilled gas port, not increase them..

[A5BLASTER]

Undergassed and overgassed can have the same effects.

How does the gun react during recoil? Is it harse feeling and does it sling the case out hard? Where does the case land? And how far away?

At first blush it sounds undergassed but it could be overgassed as well.

[bigdaddyjak]

[Klem]

big,

Are you saying you had a rifle length spring in a carbine length buffer tube?

[bigdaddyjak]

[VASCAR2]

[bigdaddyjak]

[VASCAR2]

[bigdaddyjak]

[montana]

Take the upper off the lower and put the BCG in the buffer tube. Push the BCG all the way back into the buffer tube until it stops. There should be a minimum space between the gas key and the lower receiver two American quarters thickness.. I have never seen a spec for the space between the mag catch and bolt face when the BCG is in full cycle all the way back, but there should be at least .120-.125 minimum space or better in my experience.. Out of spec buffer tubes, poor installation, weak or using the wrong recoil spring will show after doing this test common test..

[bigdaddyjak]