Looking for some opinions on load development for my new build. I just got my new rifle and custom dies for a rifle I'm going to try. It's a one off cal so there is no load for it in any of the data sites or books. It's basically a .375 Ruger case necked down to .358 which is very close to a .358 norma mag just a hair bigger. I'd like to try H1000 powder and 225 Accubonds. The next closest that I Could find is .358 STA but that's a bigger case although they do have data for H1000. What I've been reading for the last while is to fill the case to the bottom of the neck and weigh the powder. Then try 70% of that number and try it. I did that and the case to the bottom of the neck holds 88.1grs. Multiplied that by .3 and subtracted from 88.1 and that gives me 61.6grs. The data for the 358 norma is comparable to the min loads and that case is a hair smaller in all dimensions. The brass will need to fire form a bit in the shoulders so I'll have to get the real results on the Chrony after the second load but just wondering what guys that know think of starting with that load.
Wildcat load development.
- Thread starter gunner72
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"I" personally would start load development within the .375 Ruger's "safe" case capacity.
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The 358STA is only about 3 grains more capacity then the 375 Ruger (around 102 versus 99grs of water). You should be fine using that data reduced 5%. I shot H4831 with 250's in my 358STA 20 years ago. Now days there are many more powder in that burn range that will net more velocity.
RockyMtnMT
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1st trigger pull is always exciting!
MagnumManiac
Well-Known Member
I went through the same thing with my build, a 338-416 Rigby Improved 35° shoulder.
Load data is next to none.
I found an old piece of info from an old Nosler manual that gave a formulae for working out safe loads using case capacity % and the birthrate of the powder...which is not constant anyway.
Long story short, it went well and I was loading good hard data through the pressure trace without any hic-cups pretty quick.
Capacity is a full 10-15gr more than the parent case depending on what powder type you use.
I found RE33 to be the 'bees knees' and RETUMBO a close second.
A few powders have proven to be finicky, RE17 behaves badly, as does RE25 with bullets lighter than 215gr.
Most powders behave well with bullets of 300gr or more.
Good luck with your new endeavour...that first trigger pull is a dandy.
Cheers.
Load data is next to none.
I found an old piece of info from an old Nosler manual that gave a formulae for working out safe loads using case capacity % and the birthrate of the powder...which is not constant anyway.
Long story short, it went well and I was loading good hard data through the pressure trace without any hic-cups pretty quick.
Capacity is a full 10-15gr more than the parent case depending on what powder type you use.
I found RE33 to be the 'bees knees' and RETUMBO a close second.
A few powders have proven to be finicky, RE17 behaves badly, as does RE25 with bullets lighter than 215gr.
Most powders behave well with bullets of 300gr or more.
Good luck with your new endeavour...that first trigger pull is a dandy.
Cheers.
Gotcha. Thx
nicholasjohn
Well-Known Member
I'll bet that if you call Hodgdon and talk with a tech rep you could get some useful information. I did that years ago when I was working with a wildcat cartridge, and they were helpful. Nowadays, the lawyers will certainly hobble them to some degree, but you will probably get some good insight from them.
Another angle would be to pick up a book called WILDCAT CARTRIDGES from Wolfe Publishing Company. It's a massive volume, about three inches thick, and it's got a collection of magazine articles about dozens upon dozens of non-standard cartridges in it. You would probably recognize the names of most of the authors whose articles are bound into this volume.
They also discuss problems that they have run into while developing their loads, and many list a lot of loading data for various bullet weights. I'll bet that somebody has already done what you're doing here, or something that is of the same or similar case capacity. If you want, I'll cruise through the book and see what I can find. Let me know.
I have all ways thought that necking the 375 Ruger down to .358 would be a grate cartridge. I have been thinking of building a 358 STA for some time, I have all so thought of other cases as well as they would be very similar, such as the RUM, Ruger and Nosler. Nosler has a 35 Nosler approved by saami but they have not made any rifles, ammo, or brass for it, I wish they would. The reason I keep leaning to the 358 STA is I can get brass with the right head stamp from Quality Cartridge and there is good load date to be found for it. That's just me of coarse, all in all I think your .358 of the Ruger case will be a grate rifle and do a grate job. This year I pick up a .400 Whelen and got in touch with a couple guys on the 24hourcampfire forum that have used it a fare amount and they have helped me out a lot. I think you will do fine, just take your time and watch for pressure sighs. I look forward to hear your results.
Remember, this is not a recommendation, this is my opinion and I know nothing.
I can understand the desire to be cautious but I don't think 61.6 grs of H1000 is a good starting point. I don't think you will find H1000 to be your powder of choice, I think a better choice would be H4350. For a starting load, I would use the same method of filling the case and then using 80% of that for starters.
I think this is the recommendation you would get from Hodgdon.
