I don't have a Remington XR-100, I have a Savage 12VLP in .204 Ruger. I'm not at all surprised to see the reading you got with your chamber length gauge. My Savage had a chamber length of 1.877" when I had about 75 to 100 rounds down the tube. My groups have been just fine. I have 1,781 rounds down the tube and accuracy doesn't seem to be falling off yet.
I was kind of worried that the huge "jump" the bullet had to make to get to the lands would be detrimental to accuracy, but that sure hasn't seemed to be the case with my rifle. I seat my bullets for the best accuracy I can get and still have them fit in the magazine. I am getting well under 1/2" groups with the 35 gr. FB HP Bergers, 39 gr. Sierra BlitzKings and right at about 1/2" groups with the 40 gr. Nosler BTs. I'm a happy camper
