Optimum 357 Sig Reloading [Archive] - Glock Talk


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02-20-2011, 13:05
For those of you interested in reloading the 357 Sig in quantity, the best setup I could come up with is the Hornady progressive press with both the Hornady Shell Feeder and Hornady Bullet Feeder -- the new 9mm/380 Bullet Feeder Die works fine. I use the Dillon Carbide dies for Resize, Bullet Seating, and Taper Crimping.

Adjust the Sizing Die until it just bottoms out firmly on the Shellplate, adjust the Powder Die to expand the case mouth to 0.385 outside, and adjust the Crimp Die to just touch the shoulder of a fully resized but NOT neck expanded case. Set the overall length to 1.130 and you are good to go. My favorite load is 8.3gr of Shilouette with the Xtreme 124gr Flat Point Plated Bullet, but work up from 7.9gr, as 8.3 is the listed max. There is very little primer flattening compared to factory loads, so pressure is likely mild. Case life is excellent. I screen cases for overall length more than 0.005 below max before resizing, as 0.005 is the typical length growth when resized.

If you share Glock-fired cases with other non-Glock 357's, you may need a Redding Push-Thu Carbide 40S&W Base Sizing Die to remove the bulge below where the "full length" sizing die stops, which will hang up in guns with more supported chambers.

02-21-2011, 17:29
What kind of chrono numbers is that giving you by chance?

02-21-2011, 20:38
What kind of chrono numbers is that giving you by chance?

I only chronoed at 7.9gr, and got 1170 average in a 3.5" barrel (M&P Compact) and 1227 average in a 4.25" barrel (M&P). The factory load data shows 1261 with a 125gr JHP in 4" at 7.9gr, and I would interpolate my data to 1208 in 4", so we are about 4% below the factory 125gr JHP data with 124gr plated bullets. They show 1320 at 8.3gr, so I would expect 1265 in 4" with the plated bullets, which is modest, and explains the low pressure evident in the primers. Commercial FMJ ammo runs about 1340 in 4" on the same chrono.