Throat erosion - what is regarded as "normal" ?

[ecomeat]

All good input, thank you.
It's good to have that sort of feedback. As Denis is discovering, the luxury of having a bore scope opens up a whole new world of "Is It....Isn't it... I thought..."
Part of my measurement inconsistencies has undoubtedly been due to the fact that I only discovered KG1, the carbon remover, about 6 months ago. So until then, I undoubtedly had hard Carbon masquerading as a contact point.

Whilst I fully agree with Keith that having a bore scope doesn't make anyone an expert at anything, buying a Hawkeye is still one of the best investments that any shooter could ever make. It will show you things about your cleaning regime that you could never have imagined !

[aaronraad]

In terms of throat wear this is how I see things going

http://www.antipodeanindustrial.com.au/wp-content/uploads/2014/04/aaron078.pdf

My ImageShack 30 trial has expire so this is the best I could do. Edited the sketch from Lilja (http://www.riflebarrels.com/articles/bullets_ballastics/throat_angles.htm)

Note also that if the HAZ or CAZ (see http://www.riflebarrels.com/articles/barrel_life3.pdf) is a even in thickness then a shallow 1 deg taper will have a dramatic change in seating depth (x1) compared 2 deg taper (x2) if you suddenly remove a carbon layer for example. I tired to show this below stage 4 in the pdf.

[Malcolm Hill]

KHGS
I totally agree that carbon is by far the worst thing to have accumulating in the barrel. The longer you leave between cleanings the more builds up and the harder it gets to a point where it is very difficult to remove. It becomes a bit like having your own diamond manufacturing machine. When a barrel has a build-up of the hard glazed ceramic like carbon on the lands it is near impossible to remove and sometimes it will have embedded itself into the steel. Internet searches have failed to bring up any chemical or substance that will dissolve hard carbon so it is a matter of using abrasives to try and wear through it. It is always a lot easier to remove it before it starts to harden through heat and pressure. For that reason all my barrels start the day squeaky clean and never fire more than about fifty shots at most before they are returned to that condition. As far as copper is concerned it is easily removed by solvents and I still think Sweets does the best job of them all.
Regards Malcolm.