This will get you down the right path.

https://www.ar15.com/forums/AR-15/Cast-300-BO-hanging-up-on-feed-ramps/66-757474/


Hence its a combo of the 223 feed ramps needing to be wider for the wider bullet, while still guiding the round up the ramps at the center of the chamber.  
Next, make sure that you are using the correct mag, since a 223 mag inner front ribs will be too wide toward the center of the mag, and will not allow the round to feed up the center of the feed ramps out of the mag.
From here, may have to adjust the mags feed lips lengths, so the case is being released from the mag once the bullet tip has begun to enter the chamber as well.


Moving one, is verify that the mag release catch threaded end section, it flush to the face of the mag release button.  If not, then mag may not be held correctly in the mag well (held lower, or canted) and could be the problem of the low feeds.

Last one, with your hunting loads, single load a mag into the mag, insert mag and charge round while leaving empty mag in the rig, and fired for effect.  The correct effect should be mag locked back on the catch (catch in front of the bolt, and not just under the carrier), and the spent case should be ejected 10'~15' out of the rifle.  If mag is not locking back, or spent case being ejected much less distance, then police the spent case, and take a very good look at it.  Hence check to make sure that spent primer did not flow all the way to the sides of the primer pocket, the sides of the spent case are not all marred to hell, and the rim of the spent case did not get bent back from the extractor on pull.  If spent case is showing any of these signs, the suspect that ammo did go over pressure in the rig to cause the short stroking.

If none of these signs on the spent case, then round is not producing enough gas pressure, and the bolt is unlocking too late isntead.

Simply, bolt unlocking too fast, and residual bore pressure is still too great with it pressure welding the spent case to the chamber walls, and energy lost as the bolt is trying to pry it out, ends up with B/C short stroking.  Other side of the coin of not enough pressure at the gas system to cause the bolt to unlock too late, and not enough energy for the B/C to full stroke, even with the easier spent case pull.

As for reloading for a gas gun, the gun powder you use (it's burn rate speed), make a huge difference.
Simply, even through your over-all working pressure of the rounds will be say 50K with all the powders, the slower the burn rate of the powder being used, will  increase the amount of gas pressure down the gas system.  This is because the peak dwell spike of the burn of the powder is moved father away from the chamber/ closer to the barrel port instead.  So to bring this full circle on spent case checks, if rims are bent, then will need to either lower the over all working pressure of the round, or will need to move to a faster burning powder to decrease the gas pressure to the gas system.

Again, spent case rim bent backwards by the extractor on the pull, will tell you if the gun is over gassed/bolt unlocking too soon.

Also, if rig is going over pressure with factory ammo (spent primer  even flowed all the way across to be tight with the  case primer pocket walls), may be headspaced too tight as well.

You might try this as well.

Part 1: Bolt Slick Up

It is trying to extract while still under high chamber pressure... I would try a heavier buffer weight.