Chief Armorer for Elite Shooting Sports in Manassas VA
Chief Armorer for Corp Arms (FFL 07-08/SOT 02)
It's not bad, never said it was. I'm simply responding to the inference that whenever someone uses this device and removes metal their conclusion is the chamber wasn't originally reamed to NATO specs. I'm saying you can't tell simply from removing metal, since Ned's reamer is ground to specs larger than NATO's. It's conceivable you could run this reamer into a Colt 5.56 chamber and ream away some metal. Would it then be accurate to claim that Colt's chambers aren't 5.56?
To look at it another way, depending upon which freebore length you call spec for NATO (.050, .056), Ned's reamer is nearly as long above this value (.0750)as a .223 SAAMI is below this value (.0250).
Here are the spec's Ned posted at another site:
Without looking how much metal was ground off, it's not really accurate to assume the presence of metal indicates a .223 SAAMI chamber rather than a labeled NATO chamber.My reamer dimensions:
Neck diameter, .255 (Pg 293 of the Black Rifle says .255-.257)
Freebore diameter, .227 (TBR says .2265/.2285)
Freebore length, .075. NATO is .050, .223 is .025.
Leade angle, 1 1/4 degrees (same as Wylde). NATO is 2 1/2, .223 SAAMI is 3 degrees 10 minutes
Gotcha. I see what you're saying. Ned probably spec'd the reamer that way to ensure that it simply worked. Making it in the middle of the spec would probably not fix some really fubaredwhoknowswhat chambered ARs. I imagine that chambers vary widely from one manufacturer to another and some aren't really .223 or 5.56 and some are somewhere in between.
I wonder when the neck and throat are reamed to the larger end of the 5.56mm NATO spec do they then have a slower rate of throat erosion or a faster rate or if the rate of erosion is even proportional to the tightness of the neck and throat.
Chief Armorer for Elite Shooting Sports in Manassas VA
Chief Armorer for Corp Arms (FFL 07-08/SOT 02)
It looks like it would be a bad idea to use the reamer on a gun that wasn't having any problems as it would remove the chrome lining in some areas.
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