I also suspect that you and Slamfire hit the reason why the coned barrel was used in the Springfield 03--the Krag is finicky about shooting spitzers as the receiver feeding was designed for round nosed bullets but has a flat face barrel like the Mauser. When the move was made from the .30-03 to the .30-06 spitzer, the U.S. Army might have feared magazine feeding problems with a flat barrel face like a Mauser (the less generous idea is that it was designed to get around Mauser's patents)--Slamfire might know more about this as he digs around in very old archival stuff. I do know that some people have experimented with a 1917 U.S. Rifle using a flat faced barrel instead of the issue coned one as the barrels for the P14 were not coned and it worked.
Feed and extraction were carefully examined and engineered into all
successful military actions. It is almost getting to be an after thought for commercial actions, and if you read Ottesen's series
The Bolt Action he describes some 1960-1970's era actions that were particularly horrible in this regard.
I recommend anyone wanting to experience the full frustration of different bullet profiles experiment on a GI M1911 with various aftermarket magazines, and wadcutter ammunition. The GI 1911 was designed for a round nose bullet. Lead semi wad cutter bullets have feed reliability issues with the GI barrel. It was common, up to the 1980's, to pay Gunsmiths to "throat the barrel"
This picture, plus a number of the shenanigans necessary to get a 1911 to feed correctly can be found here
How to of 1911's
http://www.gunownersofcanada.ca/sho...-of-1911-s&s=34b3546a5a84945f7917cfca0bacfb6d
As someone who has monkeyed around, bending feed lips, experimenting with feed lip angles, the angle of cartridge approach, the timing of release, is not a simple subject, but are critical to reliable cartridge feed. Breech type is not a panacea for a poorly designed or poorly manufactured action. I can say, I have a cone breech M70 (claw extractor action) that was improperly machined at the factory, and cartridges fed on the left, will release late, and nose dive right into the extractor groove cut into the barrel shank. What bullet profile is used, what cartridge length is used, what cartridge taper ,shoulder angle is used, what follower is used, all will make a difference in cartridge angle of approach and release.
Soldiers were issued a rifle and issued ammunition that had been tested to feed and extract reliably. You wander beyond the parameters set by the original equipment manufacturer's, your rifle may not feed your bullets. The simple solution is to find the bullets that work. I do not recommend any grinding, welding, etc, as you may spend a lot of money to ruin a perfectly functional action.
I have a slave labor K98. The workers on the line deliberately messed up the geometry of the action and nothing short of a new receiver will make that rifle feed reliably. But then, that's what the slave laborers were intending.
Incidentally, workers in those Communist worker's paradises, lacked motivation. I have a German capture K98 that the Yugo's rebuilt, with a brand new 0.328" diameter barrel, which shoots standard 0.323 bullets rather badly. I remember the Yugo car, a friend bought one, this was when Yugoslavia was still Commie. The Yugo was an Italian Fiat built in Communist Yugoslavia, anyone old enough might understand how the combination was a natural prelude to a disaster. My friend mentioned that his Yugo would have made a "decent car" (probably wishful thinking) with 20 more hours of quality control. His car, had such stupid problems as wiring harnesses not inserted into the frame hangers. It did not take long for the Yugo to gain the reputation as one of the worst cars ever made.
