Ok lets see if I can explain this...
I have a model 10 223 in a McCree stock (which I love, got 2 of them!). The load I have been shooting is a 80g smk loaded very long. The AI 223 mags allow for a very long bullet seating. Approx 2.33 oal.

It will not feed with long oal loads. Today I was looking at it and I can easily see what the issue is. My feed problem is this, the cartridge is pushed forward by the bolt out of the mag, the bullet tip hits the flat edge of the barrel stopping forward motion. The shoulder of the cartridge is not in contact yet with the feed ramp. So it is not getting any direction to go up into the barrel soon enough. It will not feed unless I push the base of the cartridge down and allowing the cartridge to rise/tip up into the barrel bore. Why? I think this is due to the long oal, McCree chassis and AI mag combo causing the cartridge to sit higher (than the original box mag) and not contact the bullet to the feed ramp.
Short oal cartridges feed no problem, the bullet then shoulder hits the ramp and up they go into the chamber.

I can see that if I build up the ramp and/or fill in the space between the ramp and the barrel it looks like it will feed properly.

Has anyone done this? If so can you explain how? material used? (JB weld or?).

Hope that was explained ok.
Thanks