Finished a new build and started shooting. Brass is getting scratched up, just on the bottom outside edge of the rim. Stiller Predator action, in 6.5x47. I think its the extractor. My cellphone is too crappy (Blackberry) to get a good photo of it, will get some tomorrow at work. Also, there is quite a bit of copper buildup on the concave surface of the extractor. This could be related? I'm thinking the extractor is a hair too long. Thoughts? Is this something a 'smith could fix, or would it have to go back to Stiller?
Scratched brass
- Thread starter Alpheus
- Start date
The type of bolt action would be part of it, i.e. "controlled feeding" as in a Mauser action where the rim comes under (behind) the extractor claw on feeding, or the later style of bolt actions where the bolt followed the cartridge on feeding and the extractor snapped around the rim on closing the action.
There MAY be very small burrs on the extractor, but this (second type) will always leave marks over the rim of the case.
There MAY be very small burrs on the extractor, but this (second type) will always leave marks over the rim of the case.
- Location
- Ottawa origanally Muskoka
Could be scratching the bottom of the cases when the base of the cartridge is being lifted out of the mag and up inline with the chamber. The culprit may be fresh machining marks on the bolt face.
Just a thought. As previously stated a picture would help
Just a thought. As previously stated a picture would help
My mistake, it's not copper on the concave surface of the extractor, it is brass from the case. No way it is copper from the bullet.
It is a single shot, so no magazine. I'll try to find a decent camera tonight, work has been busy.
It is a single shot, so no magazine. I'll try to find a decent camera tonight, work has been busy.
- Location
- Banana Republik of Kebekistan
Are you sure you are not headspacing?
Seen it once. The case expansion was such the extractor had to work harder at extracting the case and caused some brass shavings and build up similar to what you describe.
Seen it once. The case expansion was such the extractor had to work harder at extracting the case and caused some brass shavings and build up similar to what you describe.
- Location
- Banana Republik of Kebekistan
Indeed. From your question I am guessing it is a non issue here.
Is the length of the scratches matching the dimension of the extractor? Is the bolt face perfectly smooth? Remove the bolt from the rifle and fit an unloaded case to the bolt face. Observe how the case is held in place, how the extractor interfaces with the rim.
If a fit/out of tolerance issue, I would write to Stiller and seek their advice.
Is the length of the scratches matching the dimension of the extractor? Is the bolt face perfectly smooth? Remove the bolt from the rifle and fit an unloaded case to the bolt face. Observe how the case is held in place, how the extractor interfaces with the rim.
If a fit/out of tolerance issue, I would write to Stiller and seek their advice.
The scratch is about 80 degrees, which matches with the 90 deg bolt throw. If I chamber a virgin piece of brass, it does come out with a similar but fainter scratch. Definitely looks like a fit issue. Also could explain the brass buildup on the top of the extractor, it is too long.
I'll contact the distributor and see what he can do.
I'll contact the distributor and see what he can do.
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Time for an update. I've been corresponding with the folks at Stiller, and after some gentle probing with half a pair of tweezers, it appears as if the bottom surface of the slot in the extractor is actually slightly below the boltface! Perhaps the brass is flowing when the round is fired, and the slight protrusion is being scraped off when the bolt is opened...?
As it happens, I also have a second identical predator action, so I might get my smith to swap the extractors and see if that helps.
As it happens, I also have a second identical predator action, so I might get my smith to swap the extractors and see if that helps.
