Erik Cortina Tuner

[Growler]

Montana I am having a difficult time visualizing the force that compresses the muzzle. The threads pull back in the direction the muzzle, but are stopped by the thread-barrel-shoulder with proper undercut. I don't doubt it, especially if it can be measured with with gage pins. Could you explain it?

I have nothing to offer on the tuner, but maybe I can help with the visualization of what causes bore compression and the forces involved.

Threaded fasteners bear the majority of the joint stress on the outer 1 1/2 to 2 thread rows. In our case these are the rows closest to the crown. This leads to a bulk tension in the barrel’s muzzle section—between shoulder and those last thread rows. The muzzle device threads apply an angled force perpendicular to the barrel threads, facing the bore centerline. This is the force that can locally distort the bore as mentioned.

if your font is other than mono-spaced, the following may not look right:

—> VV <— muzzle device in bulk compression

<— WW —> barrel threads in tension

— - — - — - — - — bore CL