Advice please: 308 brass question

[DiscoSteve]

This brass has been fired 5x, never annealed. After firing, the case headspace measures 1.633-1.635". A 1.633 fired case will chamber, but with some increase in bolt effort to close it. The bolt will close easily on a 1.631. So, I bumped the shoulder back to a nominal 1.630 to prevent any problems with chambering when hunting. Anyway, I noticed I got some "ejector" marks from just chambering a loaded round, and then removing it. Maybe I was interpreting this in the past as an ejector mark and thinking it was pressure? Does this false ejector mark mean I need to bump the shoulder back farther? Or it is something with the ejector?

Here is my brass from shooting today. 151 AH, TAC, CCI 200, COAL 2.835. Left to right in increasing powder charge. Shot about 1 MOA which is a miracle in this rifle doing a ladder.
47.0 -> 2821 fps
47.5 -> 2861
48.0 -> 2888
48.5 -> 2907
49.0 -> 2923

You can see the "ejector" mark on the unfired case. It was 47.5 gr of TAC, and coincidentally it was the only clean case neck after firing. I use a scotch brite pad to clean the necks as well as the bottom of the case to "erase" any prior ejector marks, etc. Thanks for the tip butterbean.

 

[JustJay]

The only time I have ever experienced an ejector mark on an unfired case was a preexisting one. *When the mark was as tall as the shoulder bump

 

[DiscoSteve]

Thanks Jay. I'm not quite sure what to make of it. I'd be curious to see if anyone else has any thoughts? Maybe it has something to do with the ejector and/or spring?

 

[riceman]

Discosteve,
Does the scotchbrite scuffing over entire base disappear except area of your extractor? If it is sounds like your bolt is smoothing out base of case except area of extractor?
Have you tried bumping back farther, to see if this changes?
Just thoughts

 

[DiscoSteve]

Thanks Riceman,
I attached pics of my bolt face. It seems to have quite a bit of brass coloration suggesting that I think the brass might be a bit too long? And yes, there is occasionally a "swipe" where the scotchbrite patina is wiped off the case head in addition to an ejector mark even when chambering and then ejecting a round without firing. I'll have to bump the shoulder back a few more thousandths and see if that goes away. That would be bumping the shoulder .005-6 compared to a fired round.

I appreciate everyone's input. I've learned a great deal from everyone here on the forum, which has accelerated my understanding of reloading over the past few years. It's amazing the things I didn't even think about paying attention to when I hunted with factory ammo!

Steve

 

[DiscoSteve]

This case measures 1.632, fired cases measure 1.633-1.635. I chambered it, and ejected it, and you can see the ejector mark. There was a bit more than normal force to close the bolt, but not by much. Prior to this, I took apart my bolt and cleaned/lubed the ejector (thanks gltaylor).

So should I size my brass to 1.630? That's 5 thou shoulder bump.

 

[joe16]

I would think that you should size your brass to wear it falls into the chamber completely (clicks at the bottom)and closes on a easy bolt closure. It might take you five or six pieces of brass to get it figured out, but that's what I size my hunting loads back to. I don't stick myself to the .002s bump back rule. It's more of a general rule of thumb for me. If you are stepping on your loads pretty hard, you might have to bump back five or six to get it to fall into the chamber easily.
Jm2cw

Speed kills and this place is awesome!!

 

[riceman]

You will need a bit more because of your still too high on your previous extractor mark(expansion into the extractor)
Not all cases may need this, due to lighter and hotter loads.

 

[DiscoSteve]

Gracias amigos. I'm going to try to get settled on a load for the 151 AH, and (hopefully) quit having to mess around with it

I appreciate everyone's willingness to help out.

 

[littlebighorn]

I seem to get more extractor marks with Nosler Brass than any other I have used. Just sayin.