u/Past_Entry_5452

I recently picked up a WLVRN chassis and am waiting on my Form 1 to clear. Once it does, I need to choose between 5.56 and 300 BO for the conversion kit.

I am leaning towards 5.56 because:

• I already have ammo, mags, and a suppressor for 5.56
• .223 is super cheap since I plan for this to primarily be a fun/comp gun
• if for whatever reason I need to use this for home defense, 5.56 seems better for my living situation (apartment) ballistically speaking
• better recoil? basing this on projectile weight

However, the 300 BO conversion kit is whispering to me:

• better suppression capabilities from a short barrel
• ammo isn't much more expensive than 68gr BTHP 5.56 that I usually get
• more likely to stop a threat with one shot (but I worry about over penetration/lack of tumbling)

I know that the FBI ballistics lab found that 64gr out of an 11.5" 5.56 barrel was the best for their use cases, which I use as a proxy for home defense. But does 300 BO really come out as the superior cartridge for home defense in a dense urban housing situation?

If the gas port is right at the end of the barrel (as in a dissipator-style rifle), does that disrupt the rotation of the bullet since there isn't much rifling left to correct its spin?

I was considering building an 11.5" pistol and stumbled upon Faxon's mid-length 11.5" gunner barrel. A brief read through reddit and forum posts about it claimed that its accuracy was poor compared to carbine-length barrels. My immediate suspicion was that the large gas port being at the extreme end of the barrel drastically disrupted the spin of the projectile which would destabilize its path upon exit. A barrel with more dwell time after the gas port would allow the projection to continue to spin and restabilize thanks to the rifling, or at least that's my theory.

Can anyone confirm that this is in fact the case? or does anyone have similar anecdotes with 16" rifle-length barrels?