Thanks Gert. I am a teacher by training but have been involved in building mining plants for the last 10 years. My mind just can’t leave a mechanical problem alone until I have the solution. Just built that way. I would love to study gunsmithing but there is little chance in Zim.I concur, this is a great write-up and explanation. You really did great work , I suggest when completing your PH licence do considering commencing studies to become a gunsmith , you really have the quality and insight into such a trade. I really think you will be great being a gunsmith...few old and knowledgeable gunsmiths has cracked this conundrum as you have done it. Johan Greying is one of the few gunsmiths I know of that knows how to make a Mauser Action/clones there off feed in any circumstances. Making a .500 Jeffery feed in a standard Mauser 98 action is the benchmark of mechanical gunsmith prowess . Thank you for this great write-up, I will definitely study it closely, yes, Von Gruff is another talented mechanical guru who is able to explain a difficult concept in such a way that even a person like me understand the difficult concept as a whole...
I enjoy this forum too. Loads of information and experience and generally people just want to help. Hopefully my post will be helpful to someone out there.
Such video may help pin point what is actually happening during the process. In reality, correcting feed issues is sometimes easier said than done though even when you witness the moment of the problem as it happens. 
Yes, try them all. But flat point or meplats seem to be the worst. My gun won't cycle with empty cases because I have tuned it for the bullet to enter the middle of the chamber. So the empty hits the side of the chamber. But it cycles a backwards bullet, so calibre sized meplat.It does pay to do the cycling drills. A long time ago I noticed large differences in the location of crimp grooves on 45 caliber rifle bullets. That location combined with nose length and nose profile determine the critical cartridge OAL and feed geometry of each loaded round in any particular bolt action. No wonder there are variables in cycling reliability.
You can take a slo-mo video (high frame speed setting) with some cell cameras of the actual feed process as the round negotiates the critical area of the feed cycle when the round is pushed over the hump of the feed ramp and into the chamber. That transition from the lower level (plane) of the magazine into the higher level (plane) of the chamber is where most of the trouble is when there is a jam. It is best done with help- it's hard to cycle rifle while holding camera/cell
Thanks for posting the heads up, particularly for anyone with a DG rifle. Never hurts checking an action for trouble free operation by cycling the bolt with as many types of bullet/OAL combinations as are available- spire point, round nose, flat nose, full magazine, one round in magazine, variable seating depths and even empty cases.
Glad you enjoyed my post. I am sure a good Smith can perfect a mauser feed, it is all about the original principles of the design.
Let me add a few tips to this great thread. I built a 404J on 8mm Cech Mauser last year. Lack of gunsmith availability necessitated me doing the work to bottom metal, extractor, feeding rails, loading ramp, and follower (a local machinist opened the bolt face). First, I discovered the magazine box dimensions are not as critical as the Paul Mauser's "cosine 30" formula indicates. I used bottom metal for 416 Rem Mag which was slightly narrower at the back than Maiser's prescription for 404J and even more so at the shoulder area. Nevertheless, it worked fine without modification. In fact, I think the slightly narrower shoulder squeeze actually helped line up fatter 404 cartridges more towards the center of the feeding ramp. Also, it is VERY IMPORTANT to tune the feeding rails in a specific order. Load the magazine fully so that right rail is being reshaped while another cartridge is underneath. Then proceed to tune the left rail with one less cartridge in the box (two cartridges in a 3+1 standard Mauser action). Once both rails have been tuned with three and two cartridges in the magazine, see how the gun cycles loading just one cartridge in the box. Odds are the right rail will now not cycle smoothly or as smoothly as when the box is fully loaded. Don't touch the rails! They are fine. The problem is with the follower. I had to carve a bit of metal from the follower keeper bar a short distance ahead of the back end.
If I could do it, surely your gunsmith friend could have handled it. My guess is he removed too much from the feeding rails. We have seen more than a few rifle build threads that involved donor guns wrecked that way. The last step I described above is where it's easy to make a critical mistake. Or, more correctly, making the last step the first step. The right rail must be modified first BUT with a fully loaded magazine. The natural inclination is to start modifying with only one shell in the magazine and work forward adding more cartridges. Modifying the left rail proceeds okay, but then when the magazine is fully loaded with three rounds, the top one won't stay under the rails. Oops. Too much metal was unknowingly removed in step one. And it's almost impossible to undo. The gun now becomes 2+1 instead of 3+1.
