I think my boolits shrunk!

[Yodogsandman]

I'm using a NEI 358 282GC mold for my 35 Whelen. I got light engraving on the bore riding nose section with my first batch of boolits using AC COWW+2% Sn. Now, the second batch doesn't touch at all. I don't have a boolit left from the first batch to double check. I guess, it's possible I could have grabbed a couple ingots of pure lead by mistake and got that mixed in by mistake. The buckets are next to each other under the casting table. I mark my COWW ingots with a chisel but, I don't remember looking before putting the ingots in the pot. Would that cause the size difference?

[RickinTN]

Maybe along the same lines......My garage has become toasty here the last several weeks and this is where I store my bullets. It seems the bullets I casts last fall and winter have all begun to grow in the last several weeks, no matter the alloy, although all of my bullets contain some degree of sb and sn. They are only growing .0002" to .0004", but I'm certain they are growing. Maybe your second batch hasn't matured as much as the last batch?
Rick

[Freightman]

they grow for a period then stabilize and shrink back

[runfiverun]

yeah, the pure lead would make them smaller.

[Yodogsandman]

To clarify and explain a bit, I cast the first batch in February and checked the fit to my bore then. Before waiting any at all. I got the mold second hand and had to try the boolit fit right away, of course. I set my overall length just off from where contact was made at 3.125". I had very slight resistance to the bolt closing. I waited three weeks to start shooting them. The second batch, I cast at the end of May, before I ran out. I only have a ten pound pot and you can only get a little more than 200, 301gr boolits from a pot. I hadn't realized that while shooting this second batch there wasn't any resistance to the bolt. I also HT'd 2/3 of the second batch to try for more velocity. With the first batch, 42.0gr IMR4064 gave the best group. With the second batch (HT'd), 48.0gr was best.

So, I was playing with the overall length with some empty cases last night and discovered the smaller noses. I wanted to tweak the O.A.L. for better groups. To start, I wanted to seat a boolit out as far as my magazine would allow and then jam it in as far as I could, then back off from there. The nose didn't touch the lands anymore. I tried an unsized boolit (.361")and that marked the first driving band at the begining of the leade at about 3.340" O.A.L. (max recommended). I tried a HT'd one sized to .359" and I could just barely see the mark. My magazine box is 3.420" inside length so, I tried O.A.L. out to 3.375" and they fed fine from the magazine, with light resistance. I have a .360" sizer on the way, backordered.

Thanks for your help, I feel better knowing what might have happened!