"light' 358429 and Unique in 357

[makicjf]

I was tinkering yesterday with 357 158 grain jacketed data from sierra and found what appears to be a humdinger of a load with Unique Winchester standard small pistol primer, for the 358429 loaded out to 1.650. It is actually dropping at 158-159 grains from this alloy. The range for the 158 grain jacketed at an oal of 1.585 ran from 7.0 ish up through 8.3 of unique. I started at 7.0 which was erratic. 7.5 was a bit better and gave me 1108-1165. Having zero pressure signs I got very steady and accurate with 8.0 grains of unique right from 1215-1225 and a steady 1420 from the 20 inch '92. This would be a great utility field load from 357 brass from this alloy.... I've not loaded anymore, yet. Given the extra case capacity viz a vis the jacketed bullet and a cast bullet weighing the same as jacketed, should I be concerned about undue wear on the GP 100 using Unique to get highmiddlin' velocity? I have 7 lbs and would love to use this load extensively.
Jason

[Outpost75]

I think that your load probably exceeds SAAMI maximum product average for the .357

I don't know which Sierra manual you are using, but in their older manuals none of the loads are pressure tested.

Current Alliant data off of their web site shows:

http://www.alliantpowder.com/reloade...id=38&bdid=100
http://www.alliantpowder.com/reloade...tid=30&bdid=83

Speaking from my own experience, in the 1980s I shook apart a S&W 19 with a steady diet of 158-grain cast bullets and 8 grains of Unique. After it was factory rebuilt and had all the oversized parts in it and was factory reblued I promptly sold it and bought a Ruger, which I am still using.

In a rifle you are probably OK, but in the M19 heavy loads with Unique caused significant forcing cone erosion and actually "dished" the rear end of the barrel exposed to the blast. Your GP100 is MUCH a more sturdy gun than the S&W 19 was back in the day, but I would still be concerned with forcing cone erosion issues using hot loads of Unique powder.

I would stay within Aliant's published loads.

[makicjf]

That's what I was thinking, but hoping it was ok. I'll back down and use 2400 or h110 for big stuff. Just got 8 lbs of h110---1225-1250 should be easy with that!
Thanks.
Jason