Quoted:
Barrels "throated" for beyond-magazine-length-seated 80gr bullets have a throat length even longer than the "military" or "5.56" chamber. They have to be specially made, as no gun comes from the factory this way. Thus the warning with the ammo. This is unique ammo specially loaded for a specific purpose (1000 yard match shooting) to be shot out of a specifically-configured rifle.
-Troy
View Quote
I beg to differ on that. The military chamber is the NATO chamber and it is by far longer in the throat area than any of the match aftermarket chambers on the market. As I stated before, to seat an 80 grain Sierra to touch the lands in a NATO chamber the OAL will be right at 2.550". And at that there is not a whole lot of bullet remaining in the case. With the Wylde it is right at 2.465" OAL. With the CLE and Bushmaster DCM chamber it is right at 2.435" OAL. It will vary a bit as to bullet OAL etc. I have yet to see or find a chamber reamer that will have a longer throat then the NATO chamber.
Also, most shoot the 80's at 600 yards and some even shorter if there is a slow fire stage. 1000 yards is okay for the 80's but most do not load for supersonic flight. The JLK 90's are more for 1000 anyway, and of course this takes a tighter twist than most use, a 1 in 6.5" for a 20" barrel.
The reason for the warning is to avoid someone trying to chamber and fire them in a shorter chamber than what the bullets are seated to. Of course you could then just measure your chamber and re-seat the bullets to make sure you have enough jump.