Muzzle thread out of spec, how to resolve?

After measuring with a 28 thread pitch gauge, it definitely appears as if the starting thread is out of spec.
The first image shows contact at the start of the thread:
1000014954.jpg

Second picture shows improvement further away from the start of the thread:
1000014950.jpg

Any thoughts on whether a die would correct the start of this thread? Almost looks like deburring the inside of the first thread would allow things to clear.
 
It almost just looks like a bur at the very end of the barrel. The light between the threads and the gauge looks even the whole way until the very end..then it seems the gauge is being held up by the very first/last thread

I'd try a small triangle file to clean up the last/first V

It's like the chamfer tool had a broken insert and just pushed the thread over opposed to cutting is back
 
Seeing as it is only an adapter, and not the barrel itself, running a die over the threads is worth trying. Might clean things up, no great loss if it doesn't work.
 
Evanguy said:
It would be nice to have a real die that is adjustable, a fixed one may be hard to start if the first thread is the issue

A triangle file is 60* so is the thread. so that could help get it cleaned up to help the die get started
Click to expand...
The die I ordered is the adjustable kind, so i can start with a larger diameter and work that first thread until the flash hider clears
 
Evanguy said:
I'd try a small triangle file to clean up the last/first V
Click to expand...

Evanguy said:
A triangle file is 60* so is the thread.
Click to expand...

boxhitch said:
A needle file would clean up that bent thread toot sweet
looks like it was dropped on its nose
Click to expand...
The above posts are correct.

For whatever reason the initial thread got pushed over a wee bit. That happens when cutting threads. It's not the end of the world. A little work with a small triangular file will solve all problems. There is no need to run a die down that ... at this time.

Use the file and I bet everything fits together fine. If not then consider running a die down the thread.
 
relayer1989 said:
After measuring with a 28 thread pitch gauge, it definitely appears as if the starting thread is out of spec.
The first image shows contact at the start of the thread:
View attachment 880347

Second picture shows improvement further away from the start of the thread:
View attachment 880346

Any thoughts on whether a die would correct the start of this thread? Almost looks like deburring the inside of the first thread would allow things to clear.
Click to expand...
The pitch looks perfect, but it looks like your gauge is resting on a large burr on that first thread. Needle file and some patience should square you away.
 
Here is the solution I came too after finding more burrs along the threads:
  • Used a small triangular needle file to chase the entire thread, giving more attention to the start.
    • Muzzle device would go on after this, but it was scratchy
  • Applied Flitz polish to the threads and used an old flash hider to work the threads putting pressure forward and back and twisting back in forth along the threads.
    • I don't know if the Flitz was necessary
After this the new muzzle device goes on relatively smooth.

Thanks all for the help!
 
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