Barnes 123 grain copper

[kevins750]

Loading some rounds for my x39 AR.

Barnes recommends 2.190 oal with a .050" jump to the lands.
How does one go about measuring this on a semi auto rifle?
Is it the same as a bolt? Do I just cut the neck of a case with bullet seated and slowly
Close the bolt and then slowly eject the round?

Also if my OAL ends up shorter than 2.190, I still have the same powder charge?

[Divernhunter]

Might I suggest you just load it so that the top relief groove is just showing. The barnes bullets like a lot of jump. I have cloverleaf groups with a .200" jump. If you look at the factory ammo everything I have seen is loaded to the top relief groove. Also push them fast for best terminal performance.
Super clean the barrel before starting to shoot them. Use a good copper solvent such as sweets7.62 or Barnes CR-10. I use wipe-out first.

[kevins750]

Thanks, your idea was my plan B.
I have Cr-10 all ready to go.
I am guessing I want a crimp, correct?

[Divernhunter]

I do not crimp but if you want to that is fine. Just be sure it is in the groove.