Pull the charging handle back, then let it go to load a round into the chamber.

The dent in the case will blow out when the cartridge is fired.

I don't understand how you are managing to dent the case unless the barrel is not indexed.

This is AR Troubleshooting, not AR Buying Recommendations.

Man, the wombats are out in full force on this topic, or should I say off-topic with which gun he should have bought instead.

If some of you have no advice on why and how to resolve his problems, but instead what to play peanut gallery with snide comments instead, suggest that you take that shite over to GD, instead of me going savage to get the flightless one involved for some corner time out's for a few days  instead.

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So back to the topic at hand.
As stated in the post above mine, make sure that the barrel extension ramps match the upper in play, and take a look at the center line of the barrel receiver ramps/the top lug between the top ramps, and make sure that the barrel extension is indexed correctly to the center line of the lower take down lug/center line of the gas tube channel in the receiver.  Hence barrel can rotate in the upper receiver barrel socket when the barrel nut is being tightened, and this can mis-index the barrel extension lugs with the bolt lugs to cause initial lock up problems when the bolt lugs, do not enter the barrel extension lugs cleanly.

Also, if barrel was swapped out, make sure to re-index the gas tube to the carrier Key as well.  Here, the gas tube should enter the carrier key with the face of the carrier about an inch back from touching the barrel extension upper open and put your finger into the back of the carrier to feel the alignment.
If end of gas tube needs to be tweaked to get it alignment with the carrier key, the gas tube is bent/tweaked over the center of the barrel and not just the back of the tube bent inside the receiver void instead.

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Now during charging a round, the bolt has to first strip the round out of the mag, and once the round in in the chamber, the extractor has to snap over the case rim to lock onto it, to allow the bolt to seat deep enough in the barrel extension to allow the bolt to rotate to lock up.

So bolt lock back on the catch, during live fire, or pulling the charging handle all the way back and letting it go, will allow the B/C to have enough speed for the clean mag strip of the round into the chamber, and enough speed left still, for the extractor to snap over the case rim and the bolt to rotate the last of the way for the bolt to be fully locked up (front of the bolt carrier to be tight against the back of the barrel extension.

As for silent charging, you can walk the bolt forward via the charging handle, but will notice that the front face of the carrier will not be tight against the back of the barrel extension (bolt fully locked up).  To get the bolt to lock up the last of the way, couple of jabs with the palm of your hand against the forward assist will lock the bolt up the last of the way (extractor to snap over the case rim to allow the bolt lugs to get the forward needed distance, and then rotate lock up as the carrier is moving the last of the way forward).

And why the bolt needs to be full locked up (carrier face tight against receiver extension face).  
Pull the Bolt and carrier out of the rifle, flip the B/C upside down, and look at the tail section of the bolt, verse the back of the carrier channel where the bolt rides in it.  Until the bolt is fully locked up (rotated all the way around via the cam pin), the back of the tail of the bolt will not protrude out the back of the carrier.  So bolt not locked up with bolt tail not  out the back, hammer will drive the FP forward, but instead of a clean primer ignition with FP against the bolt tail so it can fully produce out the bolt face, FP will drive the carrier forward to lock the bolt up the last of the way against the back of the carrier, but by the time the bolt tail does protrude out the back so the FP can fully protrude out the bolt face, too much hammer strike to the FP has been lost driving the carrier forward to lock the bolt up the last of the way, and will not get a primer ignition instead.

And a quick lesson on controlled feed, verses non controlled feeding.
Control feed is when the extractor first snaps on to the rim to hold the round to the bolt face, before the round starts to move forward.
UN-controlled feed is when the bolt just shoves the round forward into the chamber, and once the round has seated into the chamber, then last of bolt movement forward is where the extractor is forced over the rim before the bolt rotate locks up instead.
Hence Mauser bolt action is controlled feed, while a Rem 700 bolt action is not.