Greydog, Part of my answer was written above in the response to 260Remguy, so please read it there. Your observations are a bit different than his, so I will add to those remarks.
Interesting enough, I just bought an old Steven bolt 30/30 to play with and possibly to rechamber to AI. Took it out the other day to chonograph some 170 Remington factory stuff to get a performance benchmark. 10 rounds averaged 2150FPS out of a 20" barrel. This ammo was sticky to extract and also had raised, and very round primers.
I traced the stickiness to gunk in the chamber. I told the guy I bought it from he should have discounted because of my cleaning fee. He replied he would have had to charge me more if he had cleaned it.
. Anyway the chamber was dirty. I should have clearned it before taking it the range. When it was clean, the stickiness disappeared.
Re the primers, I have seen this before with very low pressure loads is several revolvers (45LC at 700 FPS, 38 special at 700DPS). Now rifles are not revolvers, but in this case both of the cartridges in question head space on the rim. I have also seen this symptom in some low pressure rifle loads, namely very rounded primers backed out out against the breech.
I think, but can not prove this may be what we are seeing in our .30/30; the result of very low pressure loads backing the primers against the bolts of our rifles. These loads are at least 100 FPs slower than they should be. That translates to pressures about 7000 PSI lower than published specs. (Testing has shown that bumping a 30/30 from 2300 fsp to 2400 FPS, with no change in any components expect the gains of powder, adds about 7000 PSI).
The only way for me to prove this is to hand load few more rounds to see if the behavior changes as the velocity rises. I think It will, but proof is proof, not theory. So, please let me adjourn until I can report on that.
Meanwhile, Zeglin did test POs theories and it is a great book.
Thanks for the replies, gents.
