Thank you, shortgrass, for the link to the saami chamber prints. Interesting stuff. If I am reading the prints correctly, it appears that there are two common chamber leade angles for .224 cartridges:
- .218 Bee
- .220 Swift
- .225 Winchester
3*, 10', 36"
- .222 Remington
- .222 Remington Magnum
- .223 Remington
The oddballs are the .22 Hornet @ 3* of chamber leade and the 22-250 @ 2* of chamber leade.
While I don't know how to compute the exact amount of freebore that these chambers would yield, I can at least generalize by comparison.
The 22-250 would have more freebore than the Hornet or any of the .222/.223 family, but less freebore than the Bee, Swift, or .225 Winchester. The amount of freebore would be much closer to the latter group of cartridges than to the former.
Judging by what I know about my rifle's length to the rifling, I would say that the freebore in my rifle's barrel is likely longer than a SAAMI chamber would be.
If I accept the idea that a "normal" SAAMI chamber would have between .025 and .050 of freebore, that would mean that my chamber has been cut with between .075 and .140 of excessive freebore.
Since my rifle has shown no symptoms of excessive headspace, I am inclined to believe that the leade angle on the chambering reamer was out of spec. I know my gunsmith rents his reamers (like many smiths do), so I wonder if the problem with leade angle would have something to do with an earlier repair/resharpening of the reamer.
To anyone who actually knows something about machining, am I in the ballpark on this?