Working Up New Load ???

[oldsnow]

I am one of those old guys that is always looking for something new. I live in Delaware a flat little state that is becoming overdeveloped with summer homes. There is talk that next year we are going to be able to hunt deer with a rifle that is, 38 calibers to 50 calibers with a cartridge case length of no less than 1.25 inches or a maximum case length of 1.82 inches. So I got an MGM 16.250", 357 maximum 1x16 twist barrel for an Encore that I don't use anymore. I think this 357 Max. will give me all I need to kill deer out to 200yds.

I have done a good bit of reloading over the years, but always with book loads. I reload now for a 357 Max. Contender handgun and a Savage smokeless ML 10. I plan to start shooting the Max reloads that I am shooting out of my Contender handgun, in my rifle which is 180gr. Hornady SSP over 27 grs. Accurate1680 and a Fed. 205M primer.

My question is when I am working up this new load for this 357 Max. rifle. is 1/2 grain increments too much of a jump, when looking for pressure signs. Thanks Harry

 

[BigBore44]

I’m not sure how the 357 Max will perform in your Savage ML-10. Should be an interesting ignition process.

What is the difference in starting load and max for that combination? If it’s 5 grains min/max difference, I’d say your fine. If it’s 1.5 grans difference, I’d say better take it to 1/4 grain intervals.

 

[oldsnow]

BigBore44 I am building a new 357 Max on an Encore frame not out of a Savage smokeless muzzleloader.

 

[BigBore44]

BigBore44 I am building a new 357 Max on an Encore frame not out of a Savage smokeless muzzleloader.

Yeah it was a joke. It was just how you worded that part of the post. So did you find your min/max for that load?

 

[Varminterror]

Half a grain is fine for 1680, at least for the first couple of steps. The Alliant data shows 2.8grn spread from start to max charge, 25.5 -->28.3 for A1680 in the .357Max (T/C). Personally, I'd make a dummy round for the new barrel, make sure your old rounds have sufficient jump, and try a few of your 27.0grn loads - it's far enough from max it won't be an issue. If it makes pancakes out of your primers, then I'd say there's something wrong with your new barrel - but it'd save you a dozen or so rounds to skip 25.5 and 26.0. If you want to push up above 27.0, fine, you have room. If 27.0 groups well, then Mazal Tov, you can interchange the two... If your chambers aren't similar enough and you need to seat the new one shorter, I'd start at 25.5 and work up. If I were starting from scratch, I'd go 1/2 grain until 28.0 unless primers, opening, or extraction told me to stop along the way. Admittedly, knowing myself, I'd likely skip to 26.5 as my starting load anyway, since I know the 1680 loads for 357max are proven, and I know I wouldn't ever load a round at its starting load level in the Max... so I'd start at 26.5 and work up. Not so different than you starting with your known 27.0 load...