SI Defense 300 Fireball and 300 BLK ammo
 

I did some measurements on the chambers today and to me it seems like this barrel is good to go with factory BLK ammo. I was worried about OAL as for BLK it is 2.26" and for Whisper it is 2.10". Another was case neck, 0.338" vs 0.330".

300 Fireball SI Defense measurements vs 300 BLK Delta Company Arms:

case max length : 1.41" vs 1.368" (this is a spec length)
case neck to rifling : 0.20" vs 0.18"
neck diameter: 0.340" vs 0.338"

YMMV and beware that these aren't scientific measurements but even visually you can see there should not be a reason why this barrel would not shoot 300 BLK ammo. Shoulder seems to slightly larger in the SI Defense barrel. If someone finds a flaw in my thinking, PLEASE do tell.

Theres a shop up the road that had some of the BLK ammo and I might go up there and grab a box or to so I can have the brass.

I wish somebody could make some "300 WTF" headstamped cases...... :grin:

JD/SSK sell 300 Whisper stamped brass....about $48 bucks per hundred.

Sorry, I get it now.....it took a minute to sink in what you were getting at. :)

Ron, do you have info on the ogive or overall length on Remington factory loads? No matter what it is, looks like my Fireball barrel will handle them though.

Any barrel will chamber them. But having a shorter throat means that full power ammo may go over SAAMI pressure limits with ammo that is otherwise within SAAMI pressure limits.

Shorter on the Whisper/Fireball or BLK? My 16" SI Defense barrel (stamped 300 Fireball) seems to have a longer throat than the 10.5" Delta Arms 300 BLK.

Well, generally 300 BLK is longer, but since 300 Fireball is a Wildcat, there is no standard for it, and anyone can do anything.