Larger Threads At End of Barrel?

[SomeOtherGuy]

I would love to see some chrono info for two barrels, same ammo, same day, etc with the only variable being the thread sizing at the muzzle end. Some groups too. Preferably the testing would have been done without any muzzle device installed.
Probably too much to ask for.

It might be easier and cheaper to find an engineer willing to do 3d modeling of the forces on the muzzle end when the bullet passes based on the differing thread types. A while back someone posted an interesting strain model for the gas block area comparing set screw, pinned and clamped types of gas block.

On the other hand, I see no downside to the larger diameter threads, so if a barrel you want is available with them just try it out. If the barrel you want only comes in 1/2x28, there's your answer.

[Clint]

3D model FEA shows approximately 50% higher stress at the thread root due to bore pressure when comparing the smaller threads to the larger threads.

[sinister]

The Texas State Highpower Rifle and Texas State Junior Highpower Rifle Teams have been shooting barrels turned from Shilen blanks by Nez Rongero this way for a few years now.

Keith Stevens won last year's President's Rifle Match at Camp Perry with a Rongero-turned Shilen with the 5/8s muzzle thread. Nez has these barrels nitrided before turning them into rifles.

[Clint]

This would be an interesting topic.

What are the general effects?

We could look into some differences between having that portion of the barrel in a extension tensile force, or more of a compressive force, and what we would register to for possible MD's. etc..

[tom12.7]

The possible differences in radiuses acting as a fulcrum axis for deflection for some possible MD's for some barrel profiles. This is kind've a thread drift for the OP, so you can email me Clint if you like. It's mostly the concept of continuous curve for use Vs a curve that has deviation(s) to that curve that more resembles different arcs combined.