Seating depth becoming more variable after annealing?

[Rmeju]

Just annealed my first (ever) full batch of brass, 50 pcs. I watched every piece to make sure the flame didn't change and that the brass didn't get so hot it glowed.

But whereas my pre-annealed brass would always seat within +/- .001", now that variation is more like +/- .003" now. I was wondering if this is normal (or a "normal" consequence of improperly annealed brass). Bullets are the last of my old a-max's, if that matters.

I can't imagine why even a bad annealing job would cause this issue, but it's the only thing I can think of that changed, so I thought I'd ask.

 

[rcmodel]

Couple of thoughts.

Annealing burnt out any residual carbon or case lube so friction is higher.

Softer shoulders may be giving a little during seating.

I'd suggest you:
Chamfer the necks.
Lightly case lube the necks with powdered graphite, Mica, or a bore brush rolled on a case lube pad.

At any rate, I think it is probably due to squeaky clean dry case necks after the fire.

rc

 

[Blue68f100]

How did you determine your temp for annealing? Templac or just by color?

Are you using one of the annealing machines that rotates the brass during the heating process?

Are you annealing before sizing or after?

How are you measuring your length? You normally get 0.005" variation due just from bullet variation. If you measure from the ogive your measurement is more exact.

I had to re-adjust my sizing dies due to less spring back when I started rotating the annealing process into my brass prep. I was moving the shoulder back more than I liked.

Like RC said with softer clean brass it may have yielded more due to seating force increased.

 

[Rmeju]

Thanks for the replies guys. To answer a couple of questions:

I am using a home built machine which does rotate the brass. I determined appropriate temp by sacrificing a few pieces of brass to set my machine up in such a way that the machine would kick the brass out of the flame just a little bit before the color of the flame changed from blue to orange.

I annealed after sizing. My thinking was that the final neck tension would be more uniform that way.

I am measuring from the ogive. I also measured a couple bare bullets, prior to loading, just to see if that variation was causing the problem, but it wasn't.

I have not checked yet to see whether the seating operation is pushing the shoulders back, but that should be easy to check.

I will try to put a little lube to see if that fixes the issue. Maybe just dry tumbling with a little polish would provide sufficient "lube?"

 

[spitballer]

I never did have much luck annealing brass. I could always get the necks to soften once by twirling them in a flame 'til they turned a light blue and then dunking them in water. Thing is, I could only get it to work once. Every time thereafter the necks just just got harder. Twirling pewter-colored necks in a flame just long enough to bring back the original golden glow of the brass seems to toughen them, though: maybe this is a form of heat-treating. I finally put an end to work-hardened brass by ordering an undersize neck: my last batch went for 20 reloads with NO flame-softening.

 

[Blue68f100]

Using the Templaq 750F on the inside of the necks told me I did not have to heat them till the flame started changing color. I'm using the Giraud Annealing machine. Their instructions are pretty good and accurate on how to setup. 1/2" flame, brass 3/4" away, 6.5 sec with 2 rotations of the brass and done. I'm annealing prior to sizing. I figure a little cold work would not hurt. Makes it easier to size and trim. The brass does not turn the darker color but you don't need to take the brass back to full anneal. Heat transfer is down the shoulder 1/4" into the sides with this setup.

 

[taliv]

same thing happened to me. i solved it with more neck tension, which i didn't really want to do. let me know if you find a better solution

 

[Rmeju]

I think I solved the problem. I think the problem was caused by the fact that I sized first and annealed second.

Based on some earlier comments (thanks rc and blue!), I checked the shoulders on my loaded rounds and found out that they were no longer set back by the .002" I had set them to after sizing. Instead, they were back at 0, or a little over. Same with the brass that hadn't been loaded yet. When I annealed, I think the stress relief altered the geometry of the brass, including both the shoulder (because they were no longer set back) and the neck (because they were unusually hard to seat).

I threw a few of the unloaded brass back through the sizer. They are now set back properly again, and the bullets are seating like butter... and I'm back to within +/-.001" now, maybe even a little better.

Thank you all for your comments! I'll try a few more tomorrow to confirm, but I think I've got it.