Semi-auto vs revolver vs derringer--all else equal

[NIGHTLORD40K]

Just a slight bit of gas escapes the back of the chamber:
View attachment 1196291

Thats kinda scary. Sneaking past the case no doubt. Wonder if they were shooting brass or steel cased?

 

[jdc1244]

Fascinating article. On the topic of freebore, I assume it has to be relatively close tolerance, not like the .410 shot shell chamber in a Bond Arms derringer shooting a .45LC where the presumed freebore might be a bit to loose to produce the freebore efffect and instead destabilizes the bullet so that the little bit of rifling at the end of the barrel does not produce the nice effect but the bullet tends to tumble, or so I have read somewhere is the problem of .45 LC out a Bond .45/.410 barrel.

I believe the free bore effect concerns only revolvers that can chamber pistol cartridges, where the effect manifests due to the shorter-cased pistol ammo – such as .45 Auto shot in a Smith m25.

Consequently, there’s little or no loss of velocity with pistol cartridges in revolvers.

My m25 is also perfectly accurate with .45 Auto.