In actuality there are 4 different and distinct .22 LR Chambers:
#1 being the STANDARD SAAMI Spec .22 LR Chamber
#2 being a TRUE .22 LR MATCH Chamber that is held to tighter tolerances than the Standard Chamber
#3 being the BENTZ Match Chamber that was designed to be dimensionally between the STANDARD SAAMI Spec Chamber and a Match Chamber to be used in Semi Auto Rifles and Handguns.
#4 is the Winchester 52 Match Chamber that has the tightest tolerances and dimensions of the 4.
.22LR Chamber Dimensions
Chamber Type
Sporting (Standard) Chamber .7751"Length .2307"Diameter .2270"Throat Diameter
Bentz Semi Auto Match Chamber .6900"Length .2270"Diameter .2255"Throat Diameter
Match Chamber .6876"Length .2267"Diameter .2248"Throat Diameter
Win. 52-D Match Chamber .5800"Length .2278"Diameter .2248"Throat Diameter
The BENTZ Chamber is a Match Chamber for Semi Auto's.
The MATCH Chamber is for Bolt Actions
The Win. 52-D Chamber is Winchester exclusive design for their 52 Match Rifles
I'd have to do a little digging to find it (found it), but I do have the actual dimensions for these 4 chambers somewhere, and yes there is indeed differences in all of them in regards to dimensions (and not just the rifling throat dimensions either.
I have had 3 different 14" .22 LR Match T/C Contender Barrels over the years, and they too were not all created equal. The first was a Blued Barrel that that chamber was so TIGHT that I literally had to use a knife blade at times to remove certain fired cases once the extractor lifted them out of the chamber. The second was a Stainless-Steel Version, while not quite as accurate as the Blued one, I never had to use a knife blade to remove a fired case. The one I currently have is also stainless-Steel. The chamber on this one seems to be dimensionally between the first two I had, and in regards to accuracy also.
I have also had a 14" On Target Technology .22 LR Match Barrel. The Chamber on that barrel seems to be about the same size as the Stainless-Steel Factory Match Barrel I currently have.
Larry