Getting ES spreads under control in a straight walled cartridge. (357max)


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R.W.Dale
December 9, 2012, 04:53 PM
Im experiencing some difficulty getting the numbers tamed on my new encore project a 357 Max 24" rifle.

I've tried two powders aa1680 and 110/296 using cci 41 and 400 primers respectively. Bullets are 180g hornady ssp.

With both powders some charges are pushing 100fps variations high to low and needless to say accuracy suffers accordingly.

The 1680 loads are seated quite long with appx 1/2 a calibre worth of bullet in the case. H110/296 loads are seated in the crimp groove.

As different as these two loads are they seem to suffer from the same affliction.

Any help is much appreciated in advance.




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DWFan
December 9, 2012, 07:34 PM
Try H4227 and load to the original pressure levels Elgin Gates intended with a CCI #450 primer.

rbernie
December 9, 2012, 07:35 PM
I'd try CCI 450s, and make sure that neck tension is adequate prior to the final crimp.

R.W.Dale
December 9, 2012, 07:35 PM
Try H4227 and load to the original pressure levels Elgin Gates intended.

Saami is 40k psi it does seem as though accuracy improves as pressures are raised.

My action is good for 65k psi + btw




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R.W.Dale
December 9, 2012, 08:11 PM
I'd try CCI 450s, and make sure that neck tension is adequate prior to the final crimp.

Aside from cup thickness cci claims the #41 = a 450

I'll get a neck tension measument but it feels pretty strong. I'm only flaring the case mouth enough for the bullet to sit straight prior to seating




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Hondo 60
December 9, 2012, 09:32 PM
Your powders are middle of the road as far as burn rate.
Maybe try a little slower powder?

Also, you didn't say what your charge is.
If you're on the upper end, then a slower powder seems to be in order.
If you have a bit of room yet, try just a little bit higher charge.

Most powders just seem to work better in the mid - higher end charge levels.

My 2, of course YMMV

rbernie
December 10, 2012, 08:15 AM
Aside from cup thickness cci claims the #41 = a 450
I did not know that.

What is the case fill? If the case fill is less than, say, 80% or so then I might suspect that you're getting variations caused by powder position. Otherwise, you're either going to have to figure out how to get more consistent burn (more case neck tension, more crimp, hotter/less hot primers) or alternatively move to a different set of powders. I would try faster before I tried slower (due to the expansion ratio at play here and the relatively small powder capacity of the cartridge).

Boxhead
December 10, 2012, 10:05 AM
I second the 4227/450 suggestion with .004"-.005" of bullet tension and a good snug crimp.

R.W.Dale
December 10, 2012, 01:22 PM
with .004"-.005" of bullet tension and a good snug crimp.

You guys may be onto something.

While neck tension felt strong on my inside mic and calipers I only show .0015" coming out of my Lee carbide die.

I swapped to an rcbs size die (non carbide slightly scratched) and that figure goes up to .005" of neck tension.

Yes I've accumulated a a few 357/38 die sets over the years

ETA I loaded 10 more rounds of the 296 load going from 22g to the Max of 22.6 grains at appx 90% load desnity. This time I used a different size die and skipped expanding the case mouths. The ammunition is ugly with a clear bulge around the bulletin shank but it does have lots of neck tension.

Ill try to get to the range in the next day it so and see if the results improve.






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