What's causing this problem?


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slowr1der
August 9, 2010, 08:21 PM
So I reloaded some more .243 Winchester loads with once fired cases today. I used 95 Grain Hornady SST loads. I noticed this once before. Anyway, on some rounds when seating the bullet the handle is a little hard to pull. It seems to be shaving a slight bit of copper off of the copper jacket on these. I pulled a bullet to see where it was shaving it from as I could see shavings. Turns out it's right around the very edge on the bottom of the bullet. You can see where the shavings were from, but not feel it. Seems almost like the case mouths are too tight after being re-sized and it's just shaving a little off of the bullet jacket when it has to push it into the case mouth. Any idea's on whats going on? When I noticed this before I didn't see an accuracy difference in that batch. In general is this okay? Or is it going to cause accuracy or safety issues?

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kragluver
August 9, 2010, 08:38 PM
It can cause accuracy issues but not "hunting" levels of accuracy. Did you chamfer the case mouths prior to seating the bullets? If so, try a bit more chamfer. This helps the bullet start into the case mouth.

paperpuncher49
August 9, 2010, 08:40 PM
Not a safety issue and probably not an accuracy issue, unless you are a bench rest competitor. It is possibly case mouths are as you say "too tight" after sizing, but that is not a bad thing as long as the case doesn't collapse when seating a bullet. It means the mouth tension should be high, essentially doing the same thing as a crimp but without crimping. I wouldn't worry at all.

slowr1der
August 9, 2010, 09:03 PM
I did chamfer the case mouths. My procedure goes like this. I tumble the cases to get them clean. Then I lube them and re-size them with a full length resizing die. Once I have done that I trim the cases, and then chamfer and deburr them. I then tumble again to get the lube off. Then I prime them, charge them, and then seat the bullet.

NCsmitty
August 9, 2010, 09:50 PM
Normally you do not need to trim the cases at each loading, only when the cases exceed the book trim length.

Check your expander ball in the FL die for size. It should measure around .002" under size compared to the bullet diameter. Any less could aggravate your problem, and the expander ball should be replaced.



NCsmitty

TonyT
August 10, 2010, 09:26 AM
I believe you are not belling the case mouth enough. I use the Lyman M die for neck expansion after sizing. Also make sure the bullet sits on the belled case before seting.

Heavies
August 10, 2010, 11:05 AM
Maybe the extra tumbling is deforming the case mouths enough to cause a few of them to be a little tight. I usually wipe excess lube off on my final inspection of the built round.

It can cause accuracy issues but not "hunting" levels of accuracy.

Plus one on that. I have noticed even slight differences in seating force will make a difference in group size, and also SD and ES numbers. IMHO neck tension plays a big factor in accuracy.

Win1892
August 11, 2010, 10:50 PM
Are you chamfering the inside?

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