Using a bore scope to find trim length?

[Kadams1563]

I have been thinking about using a bore scope to dial on my trim length to fit my chamber.

Is anyone doing this and how has it changed the carbon rings etc?

My thought process is keep firing and loading brass until it’s getting close to bolt not closing and then look to see what length to trim right at the chamber area if that makes sense.

Or just keep trimming at book length? Lol

 

[Oryx]

I use mine to validate my trim length and keep mine pretty tight to the chamber dimensions but not all the way. The case needs to expand a little bit. If your load and brass conditions don't allow your neck to seal, you will still get carbon bypassing ....

Length alone isn't the only concern.. Brass to chamber fit, bullet relationship to throat, powder burn rates, etc will impact sealing and bypass

 

[Near miss]

I did check mine on my semi, just to know how much leeway I have. Realized I will never have to trim for that chamber, for safety reasons at least.

The general consensus (whether true or false) is that optimized trim length reduces fouling.

Making the brass neck longer might not help in accuracy if there is uneven pressure/friction force on the bullet.

I am not sure on chamberings, but if I remember right, my 223 brass got shorter upon shooting and then longer after resizing.
All in all it grew length over uses, but quite slowly.

As always, do your own research

 

[Huskydriver]

I do this.... I only trim when the brass is getting near the end of the chamber.

 

[Haney]

Great way to realize people trim for nothing all the time . I use Sinclair plugs to know exactly what I have , borescope is great for a visual but no way to get exact measurements .

 

[Schütze]

Great way to realize people trim for nothing all the time . I use Sinclair plugs to know exactly what I have , borescope is great for a visual but no way to get exact measurements .

How close to this measurement taken do you let your case necks grow before you trim?

 

[Just Chuck]

Good ideas on bore scope....I'll give it a try. I have used mine to inspect in side cases to look for case thinning and other defects.

 

[Haney]

How close to this measurement taken do you let your case necks grow before you trim?

I keep them back about .010" , if they ever grow that far . A lot of factory chambers (Remington) are very generous and trimming is only needed if you want them all at a uniform length .