I was just wondering what throat erosion looked like to the naked eye as I have an m96 6.5x55 that I think looks like it has throat erosion yet a gunsmith I know looked at it and said it was in reasonable nick. My gundealer who sold it also said it had a pretty good bore yet the lands look worn down at the start of the rifling just ahead of the chamber, it looks in terrible nick to me however I am in-experienced and have mostly new rifles.?

Regards PC

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PC,

Imagine you had a little sand blaster and the outlet was the same diameter as the case neck.

Now you stick this blaster down the chamber with the outlet stuck in the neck of the chamber and then turned it on.

You let it run for a second or so and then pull it out and have a look up into the barrel through the chamber end.

If you kept repeating this process, you would see what the barrel would like as more and more shots were fired through it.

Initially, the sharpness of the rifling would be lost. At the very early stages this is so small it might not be apparent. But if look down the barrel from the muzzle end, you would then notice the difference in the rifling as compared to looking through the chamber end.

As things progressed the rifling would be worn down further and also extend further up the barrel. You would also notice the bottom of the grooves starting to get a rough appearance.

As it progressed some more the first part of the rifling would be completely gone.

In general terms, by the time all this becomes quite obvious, the barrel still has plenty of life left.

In calibers with big cases for the bore like 7mm Rem, 264 etc.you might first notice erosion in at little as a few hundred shots and even less.

I have a mate's 25/300 Win here at the moment and it has probably only fired a 100 shots and you can already see the edge of the rifling at the start is dull or rounded.

That is the best description I can give.

Mike

You won't see it well by eye without a borescope. Make a cerrosafe cast and you will see the erosion and see just how it progresses. I do this on my .50BMG match barrel so I can tell when its time for a new one.. It looks like sandblasting starting at the end of the neck and moving foreward into what was once your sharp lands.-Rob