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93: A good example of metal displacement to be sure. SOME does appear to have been pushed back along the bands and I would think such displacement could stress lands more than with a softskinned jacketed bullet {?} but that seems to be the reason such bullets are purposefully made slightly undersize. But the lion's share looks to have smeared back into the groove behind each band as noted above. And your barrel seems to have allowed the lateral expansion.

Of course, a thick-STEEL-jacketed bullet is going to cause stress, too, and thus the need for some sort of comparative test as Daryl called for in the first place. And Barnes says in the posted material that they have performed such a test using pressure as the standard by which to compare the two. Maybe pressure is not the only thing that should be examined and compared, but can we make sense of a statement that pressure has nothing to do with OSR? Such a statement would seem to be ridiculous.

The bronze French Balle D bullet is one example of a "hard" {or is it?} bullet used in massive quantities. Another example is various military AP rounds and some standard military steel core bullets with excessively thin lead envelopes under the steel or gilding metal jacket. Some such bullets have been noted as being hard on barrels but the damage is normally noted as increased rifling wear.

Could it be that the typical military barrel is just thick enough that it supports the rifling so as not to allow and expansion of the brrael beyond its springback capability and the doubles with osr have tubes so thin they lack this support?

Sounds plausible, but this nevertheless doesn't explain the existence {if it exists} of osr showing up on the whole length of the barrel unless bullets are not engraved, and the lands are merely "getting out of their way" the whole length of the bullets trip down the bore.

Can anyone show a pic of a recovered bullet that is NOT engraved?

This has been a fun mental exercise, sort of like twisting a Rubic's Cube.

Except nobody seems to have been able to line up the colors yet.

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"Can anyone show a pic of a recovered bullet that is NOT engraved?"

I don't have any photos of the spent North Forks I've shot on photobucket. But the North Forks are a true driving band bullet and the body of the bullet is NOT engraved. Only the bands engage the rifling, the body does not. The photo of the Barnes displays the problem, the body of the bullet IS engraved, unlike that of a true driving band bullet, North Fork or GS Customs for example.

Also, regarding the driving bands on the North Fork or GS Custom, the spacing is such that there is more width between the bands than the width of the bands. So all of the material displaced when the bands engrave fits between the bands.

Perhaps someone can post a photo of an expended North Fork or GS Custom?

JPK

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