Inquiring minds want to know! I have shot many thousands of them through my rifles...

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Of the Troops & For the Troops

FMJ is generally plinking ammo. The stuff I’ve seen has been Mil Surp 147 gr bullets. I load all yen .3p0 blk and I either load 125 Speer TNT’s or Missouri Bullet Company coated, cast heavies; I think they are 245’s. Both are cheap enough to cover shooting. I’ve got a 25 yard zero with the 125’s that puts me dead on at 200 with my suppressed 8.5” sbr.

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https://facebook.com/M2bKydex/

As I remember and understand it, going back to the beginning, when it was a proprietary round the Jones 300 Whisper had one use.
A very heavy for caliber projectile traveling at subsonic velocities for specialized uses. These were called 300X221 in some uses due to legal issues.
Then folks found that it could utilize light (125 grains or so) bullets to provide for a hunting cartridge in the AR and Contender.
Proprietary cartridges can not obtain SAMMI acceptance so the dimensions were finalized and the Blackout came about.

125 NBTs for speed and hunting along with some 150s, heavy 180 and above for the fun and working loads.

Look on a ballistics program on the performance of a heavy projectile 30 caliber bullet (240 gr) moseying along at 1100 fps or so. Think this is a hint for the original design purpose.
Plink and play with cheap FMJs and then use it for hunting with NBTs or comparable activities.
I could be wrong, but the NBTs may still give you a little too much penetration for social occasions.
Anyone ever test it with 110 gr. RNSPs?