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AJC1
Member
So I have some 200 grain gas checked cast I was looking for load data on and it surprised me the non-existent change in load data by weight.... like weird.
7.7 Japanese
- Thread starter AJC1
- Start date
Interesting… I saw that in another cartridge I was researching awhile back. Cast data. (I’m looking into adding that to my already out of hand hobby)
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AJC1
Member
It's a way for me to control supply and lessen the amount of times I have to test. Once I have data for a bullet I cast, no one can't take that. Unlike bullets that people love and get discontinued. It's basically the next level of having enough primers and enough powder.... some fall down the whole and start collecting moulds
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AJC1
Member
You might want to check after the 30s where 303 is. I just found it, and it answered the headspace datum question...mine is page 351...
Mark_Mark
Member
- Joined
- Jan 9, 2021
- Messages
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I been slacking! my 7.7 case is still in the Rock Chucker, it won’t move from there till I load it!
BJung
Member
Has everyone slugged their barrels? The bullet diameter should be .001" over bore diameter.
BJung
Member
Has anyone shot cast bullets yet? I have test loads made for a future range trip. I have Dacron now for light loads using 2400.
BJung
Member
Since I posted last, I looked the at burn rate chart for AA4350 and it is next to R17. R17 is the factory equivalent to the powder used in GP11 loads fired in the 7.5 Swiss. Would the case capacity of the GP11 be the same as the 7.7x58?? I got excited. No, the GP11 case capacity is 65.1gr water and the 7.7x58 case capacity is 60gr water. I couldn't find load data for AA4350 but did so for the 7.5 Swiss along with IMR4350. Loads for this cartridge is 1gr more for AA4350. I will take my IMR load data and work in the middle and up.
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AJC1
Member
I've shot a few my dad loaded, no idea his data. I have .313 200grains that he bought. I plan on loading and testing that 28-30 grains of imr4227. I'm kinda surprised there is no 4198 data. I thought that was the cast bullet powder. After the 200s are gone, I'll use 165 or 175 cast. I just got my two step mandrel from noe....
Armorer 101
Member
I have owned several type 99s and 99 conversions, a word of caution, depending on when manufactured, they can vary greatly in quality plus adherence to any specifications.
Suggest that relying upon a manual to size or trim brass is a problem as the manual may be printed so anything created per the manual will fit in the bolt face and any chamber regardless of how small.. This usually means accuracy is traded off for function. If the entire world uses a trim to length at .010 less than max brass length, and that manual says .024 what do you think happens in front of the chamber on too short cut brass due to hot gasses, like it not only burns the throat, but also the chamber.
Reload for your rifle as a one off custom. Slug the barrel, examine a fired, as is, factory piece of brass, then trim, if necessary, or do a chamber cast and cut the new brass to length per your chamber cast, then neck size only.
Hope this helps someone. By the way, you can use 06 start loads, then work up for the 7.7 I have found this works pretty well for powders not shown for the 7.7 and the 7.7 type 99 actions of early manufacture are very strong.
Suggest that relying upon a manual to size or trim brass is a problem as the manual may be printed so anything created per the manual will fit in the bolt face and any chamber regardless of how small.. This usually means accuracy is traded off for function. If the entire world uses a trim to length at .010 less than max brass length, and that manual says .024 what do you think happens in front of the chamber on too short cut brass due to hot gasses, like it not only burns the throat, but also the chamber.
Reload for your rifle as a one off custom. Slug the barrel, examine a fired, as is, factory piece of brass, then trim, if necessary, or do a chamber cast and cut the new brass to length per your chamber cast, then neck size only.
Hope this helps someone. By the way, you can use 06 start loads, then work up for the 7.7 I have found this works pretty well for powders not shown for the 7.7 and the 7.7 type 99 actions of early manufacture are very strong.
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AJC1
Member
I have an early war capture that's in good shape. The base of the case/rear of the chamber is big and bulges. I figure I would use 30-06 federal brass and toss them after about 3 shots. Is a race between me and the primer pockets failing.
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AJC1
Member
So now I have a pretty decent pile of .313 165 grain gas checked and lubed boolits ready to go, load data seems to be sparse. I could try the 28-30 grains of imr4227, but I am just getting a 45c load that is coming together.... I got 5 lbs of imr4198 the holly grail of cast boolit powders. There has to be a load out there somewhere....
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AJC1
Member
Spent a few hours converting another pile of fed 30-06 to 7.7. So my refined process is to set up the lathe with a collet and a stop and use a modified parting tool to make the case 2.290. The soft cases still don't part great but thats why I leave them a little long. Step 2 is flame anneal. Step 3 is size. Step 4 is trim to final length. This group is trimmed to 2.280. One book lists 2.283 as max so I'll roll with that this time. Chamfer debur and done. Processed 85 more so I can take everything out of service except my made cases till I get the stuff to make false shoulders and fire form.
BJung
Member
AJC1. Are you using a Lee mold to cast your 200gr bullets? If so, the diameter is .308. Will you beagle the mold, meaning expand the mold diameter with maybe valve grinding compound?
BJung
Member
I size first and trim. Why do you trim first?
BJung
Member
Do you have any AA9 or 2400 for a 16gr gallery load. I have some Dacron I can mail you to test with.
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AJC1
Member
The 200 grain bullets were from my dad and I beleave bought on the market. My noe mould is dropping .316 with Lyman #2 so they are plenty big.
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AJC1
Member
Geo posted a imr 4198 load from the ideal manual I found whilliat reviewing this thread. 26 a gets 1900 fps which should do nicely...
