"I noticed that when I fire the rifle with the magazine resting on the shooting platform, the issue returns."

Is it possible, your mags feed lips are "dragging" on the carrier group ?

Maybe a new mag catch could help ?

Is the gas block not adjustable on this rig?



As for bolt bounce, should not be a problem since not running rig in full auto, and if the bolt is not locking back up after the bounce, then not lubing with CLP to begin with, or something has major binding instead.

Lastly, when was the last time the recoil spring was replaced, since that needs to happen every 4K rounds.  Also if gas block is not adjustable, then may want to thing about going to extra tension recoil springs.
If you run into the problem of not able to find replacement recoil springs, then Brownells sells spring stock, and you can make your own replacement springs.

Not able to add an adjustable gas bolt to key since gas tube is welded to top of carrier, gas passage in front of the bolts,and adjuster would  have to go through the bolts, unless threaded channel to front side of key isntead.

Also to point out, if dead blow effect device was to be added to keep the carrier from bouncing off the back of barrel extension, it would need to be added to the extended key.  With it not solid, front tube welded to top of carrier, such a device on the extended from end of the key front end, would just cause the weld to break in time.



So would be easy to intercept the gas passage at the front block, drill and tap  for set screws shown above

Hence figure out size of gas passage on block, to come up with a set screw that is wider than it, drill the intercept channel for set screw to other side of passage void, go in with 90 degree drill bit to V channel the other side, shorten and 90degree the end of the set screw, and you now have a gas adjuster that can not only close off the gas passage in the block, but backed off to open the gas port as needed to reduce the amount of pressure out of the barrel port to B/C, so bolt is not opening too soon to cause the rig to over function.

Also to point out, front channel as also been drilled and taped, for a jam screw to hold the adjustment set screw in place.  So front jam set screw is loosened, side gas screws is set to just allow the bolt to lock back on last round out of mag, turned out another 1/8" for good messure to add just a touch more gas, and then jam screw is tighen into side of set screw, to retain in in place.

If machining is beyond our skill level, then check with the local guys, since one may be a machinist to do the work for you.  It a 5 min job if you know what your doing, and really just paint by numbers using the DRO.

This will at least resolve the bolt opening too soon for the ammo in play, and may slightly help with the bolt bounce.  I say slightly, since will reduce the amount of carrier slamming into the back buffer too cause the carrier to be sling shoot off it, but without a buffer in play as the bolt does go to lock up, still going to have the carrier bouncing back off the face of barrel extension at lock up.

As for carrier on the rig, it just a cut standard AR carrier, and you can tell that its a AR10 carrier, since the hammer for it uses is the narrow type, while a DPMS/stoner carrier uses the wide type hammer isntead (wider hammer will bind in the ar-10 lower carrier opening).


As why it never caught on (even with it being a folder that should have sold like hotcakes for para use), it was due to lack of buffer to control bolt bounce for full auto fire in the first place. Hence sear release gap will grow as the hammer rear tab and auto sear wear, with to much service time to keep that in check at .083" so you don't have problems with fail to fire in full auto to start with, and semi with the carrier not fully returning to be tight against barrel extension at trigger pull.

With buffer system, you can have an auto sear gap grow well into the .100" range, and since the buffer will keep the carrier from bouncing off the barrel extension, don't run into  fail to fire problems with FP being block/bolt staying locked up at feed to begin with.

Yep, and just different type gas key.  
Take a close look and can see the standard ramps for the FA, when the standard carrier was cut to shorten it to work without an receiver extension void area. Hence back FA receiver was cut in half, and you would never machine a carrier from scratch, to have the back half of FA detent still in play.


So only thing special on the carrier, is just welded on long tube key, so the recoil spring can be added to it, with it's back side up against the front of the receiver to pull the B/C forward, instead of buffer and recoil spring pushing the B/C forward instead.
And to note, if it was machined specific for this rig, then ID of carrier read did not need to be rounded ,but could have been slotted to have more weight in the carrier as well.

As for DIGS system, lets just say it would have been better as a piston driven system instead.  
With piston driving system, less problems of the spring tension on the forward rod to cause deflection since it can be solid, and piston system could have come with an gas adjuster as well.  So would solve the semi bolt bounce problem of the carrier not coming all the way back forward, since the bind up up at the end of the extended key, but without buffer, still have the problems with it in full auto isntead.

Hell, to point it out, even the lower receiver is just a standard AR milled pattern,since it has a channel for the buffer retaining pin, which the rig does not use to start with.

Gas key,

The long  center void tube gas tube section is welded to the top of the slightly higher lower piece, stepped drilled for the key bolts,  and bolts are used to hold the entire thing to the top of the carrier.

Take a look at the back end of the key, and you can see the welding fillet and grind  lines on it.


If just bolted alone, then forward spring tension pulling the B/C back forward, would peen the hell out of the bolt channels on it, to cause a nasty gas leak in short time.