After sizing down the 7.62s with 5 gradual diameter decreasing bushings, and neck turning, the cases were run threw the FL sizing die. These sat over night and in the morning the trim to length began. As the cases came out of the FL die the night before they fit the turning mandrel. Come morning a fare number would not accept the mandrel. These were run through the FL die again to expand and they went onto the mandrel just fine. It would lead one to think that there was a shrinkage problem? This is the first time in 53years of loading and wildcating that I've seen this condition. The learning process never ceases!
Lest you wonder why this is being done; the intent is to compare the capacity and test these cases with identical loadings to the Norma cases. So far we know that the Norma cases yield great results.
55gr., bulk, psp Win.23.8 gr. acc2015 , fc 7.62x39 FC cases, ""WLRM"", oal= 2.030" Fire Formed. 2952 to 3015 fps. ,Mild, Clean, 10 shot 3/4" group at 50 yds. including first two shots. Cases fire formed beautifully.
Best group of the day was shot by my cousin. 52gr. fb-hp, berger 27.7gr. IMR 4895, Norma case, WSR, oal=2.040". 5 shots 1/2" group at 100 yds.
This sow's ear is really looking good.
The case oal prior to fire form was 2.040" after fire form it was between 2.016 and 2.020".Everything has just seemed to go right on this project roger

quote:

This sow's ear is really looking good.

Bartsche. My oft quoted trueism is added to this old saying and it is that while you may not be able to make a silk purse out of a sows ear, you CAN make a pretty damm good pigskin wallet.

Interesting finding on the resized brass after it sat for the night. I wonder if you did a case neck thichness comparison on those that fit the mandrel and those that did not. Have you found any percievable reason for this anomally yet. Annealing at any stage in the necking process? I wonder if an annealing before the final pass through the FL die may have side stepped this condition. I have an increasing interest in the 6.5 Grendell and thought to form from the parent case as well if and when the project goes ahead.

Von Gruff.

bitchy case to make isn't it. somewhere or another i accumulated a 6mm ppc form die. that took almost all the work out of it. it formed 762 to 6 in one shot and one pass thru the 22 ppc die and voila

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Originally posted by butchloc:
bitchy case to make isn't it. somewhere or another i accumulated a 6mm ppc form die. that took almost all the work out of it. it formed 762 to 6 in one shot and one pass thru the 22 ppc die and voila

Don't have a 6mm PPC die and if I try to form in one press through the 22-PPC die I get the big accordion.
Even using the bushings we get a little mushrooming. This, however, may be beneficial as when it is fire formed there is a little extra brass available preventing length shrinkage.
FYI; FC formed brass from 7.62x39 weighs 122.8 grns. Norma = 111.4grns. fc case + water weight =154grns., Norma case + water weight = 145grns.
ergo; fc capacity = 2.01cc, Norma= 2.14cc.;more than 10% difference.
With this, plus the difference in primers, caution might be in order. roger