Ditto on a light radius chamfer at the back of the chamber entrance, and would not use a counter sink type cutter to do this since it going to angle cut into the chamber too deep isntead.

Just chuck the barrel in a lathe, and using say a chopstick with 400sandpaper on the dowel so your not touching into the actual chamber walls deeper than just the edges, should be able to produce a light radius chamfer to break the sharp edge on the back of the chamber.

Hence you do not want the chamber entrance chamfer late of raduis to be beyond the case webbing of the case, leaving the case unsuported instead.

So you first start off with the a every so slightly radius of the entire barrel chamber entry, and then if needed, you can increase the chamfer on the bottom of the barrel chamber to slightly enlarge the throat ramping on the bottom of the chamber entry to give it a slight feed ramp; but again, not deep enough into the chamber side walls to get past the webbing inside the case to unsupported the case when chambered.

So here is what your trying to go after,


Next, work with the feed ramp block that you have installed, to couture it so it feeding the rounds out of the mag box into the chamber cleanly centered next.

This is what you installed,


So to start off with, the top contour of the block should have only been top curved radius so the bottom of the bolt  just cleared the top lips of the feed block as it the bolt is been pushed forward.  Next the ramping of the block is angled both sides so as the bullet is being feed into the chamber both side of the mag box, it going to force the tip of the round in line with the center of the chamber as well.  So will bank that the you have a huge gap between the bottom of the bolt and the top of the feed block to start with, and even bigger gap between the sides of the bottom of the bolt and block as well.  With a new block that is radius the same as the bottom for the bolt to just clear the the bottom of the bolt, center top channel orientated up the ramp, this will clean up the tip feeds of the round out of the box both side, to center feed into the chamber instead.

If you need me to mock something up, can do so, but it just going to look like an upside down grooved Y channel up the block block face, with the  end top and even the sides of the bolt much higher than you currently have (again, with only about a .010" clearance of the bottom of the bolt and the the top of the block, and top end of block contoured the same as the bottom of the bolt as well) .

Lastly, mod the extractor so when the case rim is coming up the bolt face on the increased angle to the extractor claw to lock into the extractor on feeding (again increased rim angle due too the shorter round), it can get under the extractor on the control feeding so it not binding up up there.  Hence the case rim locks onto the extractor as is being pushed out of the mag on a mauser action (controlled feeding) and not as the bolt is locking up like say a rem 700 action.  So with a shorter round, the angle of attach is going to be steeper into the chamber, and this causes a greater angle of the rim against the  bottom of the extractor claw and bolt face on the initial lock into the extractor during the feed isntead.


Note, you don't have to go this buck wild with the extractor, but you do have to increase the gap at the bottom of the extractor to the bolt face, to allow the rim at a much greater angle to be able to slip under the extractor without binding up as is finally clearing the box lips and locks into the bolt face. Hence we need the tip of the bullet to be in the chamber before it clears the end of the box lips and the round is now being completely controlled by the bolt face alone from that point instead.