The Firing Line Forums - View Single Post - 30 Carbine equals 357 mag from lever gun?

**44 AMP** · May 25, 2016, 09:57 PM

Everything gets a velocity increase from a longer barrel, even loads optimized for handgun barrel lengths. How much of an increase varies.

The problem with a semi carbine in .357 Sig or 10mm is there is no purpose built carbine for them, and adaptation of existing designs is ...cumbersome.

I expect you could do it with an AR, the drawback being a lot of excess..space and material.

Blow back is possible, but would have to be too heavy to be popular, if even practical. So, locked breech is the way to go, but its still going to be heavier, more complex, and more expensive than alternatives (like lever guns)

Also I would be quite surprised if the .357 Sig matches the .357 Magnum outside of the 125gr load in any barrel length.

May 25, 2016, 09:57 PM	#26
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 28,860	Everything gets a velocity increase from a longer barrel, even loads optimized for handgun barrel lengths. How much of an increase varies. The problem with a semi carbine in .357 Sig or 10mm is there is no purpose built carbine for them, and adaptation of existing designs is ...cumbersome. I expect you could do it with an AR, the drawback being a lot of excess..space and material. Blow back is possible, but would have to be too heavy to be popular, if even practical. So, locked breech is the way to go, but its still going to be heavier, more complex, and more expensive than alternatives (like lever guns) Also I would be quite surprised if the .357 Sig matches the .357 Magnum outside of the 125gr load in any barrel length. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.