Tony, Quickshot makes a good point. Cleaning the chamber neck, throat & beginning of lands & grooves thoroughly would be an essential 1st step. Use cleaners that will remove both powder & copper fouling. Measure your bullets to insure .2240" dia. at 90 degree intervals around dia. ( you can't get a .2242" to .2245" bullet through a .2240" throat w/ hand pressure.) The .223 rem throat is very tight. As small as .2240" on some reamers as opposed to the larger throats on 5.56 NATO. The 1.795" reading of contact ring to base is within a couple thou. of the reading in my McGowen .223 rem using 55gr. Nosler which has a slightly different ogive shape. You may have to settle for the "ring" seating depth for your max OAL to insure ease of feeding. You can use your collet die to adjust neck tension to get a snug slip fit of bullet for determining " just touching" depth. I'll be happy to explain how, if you'd like. The accuracy you're getting is outstanding! So, personally I wouldn't do anything to modify the rifle/chamber that might ruin your results. Sounds like Keeki had a similar circumstance w/ no negative results. I'd also seriously look into a seater die that would give you more seating depth. Your Lee seems to be limited in this respect. Maybe that's why Lee gave you such a good deal ;D Dale