Does anyone have any suggestions for a good cast bullet or mold to get for the 7.7. I was thinking in the 140-155 grain range to keep the pressure and wear down. Also had intentions of powder coating the bullets so if a mold works well with that it would be very helpful. A lot of the 303 British mold I see are heavier. As a final question, do any of the older lyman cast bullet manuals have 7.7 listed. I would try and find that edition if it has good information.
Bullet casting and loads for 7.7 Japanese
- Thread starter AJC
- Start date
I have some regular Lyman manuals from 67ish (42nd edit??) and 78ish (45th edit.) that have cast bullet data for the 7.7 Jap as well as mould numbers, although most likely are discontinued. None of the newer powders are listed, just IMR'S and some Hodgen. Hercules rifle powders listed are discontinued, but have the pistol powders that are still available.
I can scan them into .jpg format and email them via a PM, I think. Don't know for sure.
I could take a picture of them and post it here, but haven't done that before so have no clue as to "how to".
Did a little reading in manual, those bores apparently vary from .311" to .316" and emphasize measuring bore to ensure getting a mould which would cast a bullet large enough. It would be cool to have one in .312-.313" bore, use 32 cal bullets from 100-115 gr readily available cast, plain or coated. There may be some of the commercial casters which already heavier standard weight cast bullets for the 7.7 & 303, an alternative route instead of casting your own, depends on how much you will shoot it and for what purpose.
Don
I can scan them into .jpg format and email them via a PM, I think. Don't know for sure.
I could take a picture of them and post it here, but haven't done that before so have no clue as to "how to".
Did a little reading in manual, those bores apparently vary from .311" to .316" and emphasize measuring bore to ensure getting a mould which would cast a bullet large enough. It would be cool to have one in .312-.313" bore, use 32 cal bullets from 100-115 gr readily available cast, plain or coated. There may be some of the commercial casters which already heavier standard weight cast bullets for the 7.7 & 303, an alternative route instead of casting your own, depends on how much you will shoot it and for what purpose.
Don
I’d go for a 200+/- grain like a 314299. It is available from many custom moulds. Loaded to 2000 fps or so, it should serve you well.
http://castboolits.gunloads.com/showthread.php?160551-CB-Load-for-7-7-Jap
Photos from Lyman 45.
Diameter should be larger then groove diameter by at least .001" Use a Lyman M die to open case mouth for bullet seating.
Photos from Lyman 45.
Diameter should be larger then groove diameter by at least .001" Use a Lyman M die to open case mouth for bullet seating.
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DirtySteve
Gold $$ Contributor
Why use a cast bullet? Any way use a gas checked bullet and keep the velocity down around 1500 fps..
Read note in photo. The groove diameter, if .317" will no shoot well with jacketed diameters.
Cast lead can be made large in diameter. But the loaded rounds neck diameter must let the rounds chamber correctly.
The condition of the barrel, if in bad shape, may not shoot well with lead or jacketed.
I like the idea of being able to slug the bore and then size the bullet for correct fit. Also searching for bullets dont give a large amount of results. The 312 hornaday bullets look good but casting appeals to me as I inherited the equipment minus the one mold I would buy for this gun.
It shoots decent with the few factory hornaday rounds I have put through it. The barrel was inspected with a bore scope and was in decent shape with no rust or pitting.Read note in photo. The groove diameter, if .317" will no shoot well with jacketed diameters.
Cast lead can be made large in diameter. But the loaded rounds neck diameter must let the rounds chamber correctly.
The condition of the barrel, if in bad shape, may not shoot well with lead or jacketed.
That 155 with unique or 2400 is exactly what I am looking for. Now if I can locate that mold I'd be in business
DirtySteve
Gold $$ Contributor
Read note in photo. The groove diameter, if .317" will no shoot well with jacketed diameters.
Cast lead can be made large in diameter. But the loaded rounds neck diameter must let the rounds chamber correctly.
The condition of the barrel, if in bad shape, may not shoot well with lead or jacketed.
Sorry, I should have read that. Makes sense as they went to the 7.7 mid war. War time manufacturing can be poorly done especially when you are loosing the war. By the way I just got done cleaning a 6.5 Jap rifle that was a war trophy. (The owner of the rifle actually has the letter from the Department of the Navy for it). I think it still had cosmoline or some such product in the barrel. It was a beast to get clean. But wow it is clean now and a fast twist. Now to find load data...
The 311466 155 gr may not provide a diameter thats usefull. The 311 is as cast diameter with Lyman #2 alloy. This alloy has a good amount of antimony. The more Antimony in an alloy, the larger the as cast diameter. Make bullets harder also.
Wheel weights will be smaller in diameter.
Best to slug your barrel first, if you have not done it already.
Wheel weights will be smaller in diameter.
Best to slug your barrel first, if you have not done it already.
Finding an oversized mold would be ideal as sizing is a lot easier and cheaper than swedging to a larger size. Might even be worth a custom mold to avoid the alternatives.
I dont know exactly how much you can grow a bullet with powder coat and stay reasonably accurate.
About .002 I believe.
That's the same number I just herd on fortunecookie45lc video. Seems like the ticket.
One thing when selecting cast bullet weights. While it is best to have the bulletin start out at .001 over groove diameter, you can get good results with bullets a thou or two under groove diameter. The British knew the groove diameter tolerances were all over the place, so the designed the bullets to “setup” upon firing. This “setup” is the same mechanism as the expansion when you smash a rivet.
In order for this to work bullet design and hardness as well as powder selection are key variables. In artillery circles they call this phenomenon “setback” and is usually designed OUT of the round as the shell can actually deform enough to affect the exterior ballistics resulting in a short round. So sometimes a slightly longer bullet made from a softer alloy can give better results with unlettered diameters.
In order for this to work bullet design and hardness as well as powder selection are key variables. In artillery circles they call this phenomenon “setback” and is usually designed OUT of the round as the shell can actually deform enough to affect the exterior ballistics resulting in a short round. So sometimes a slightly longer bullet made from a softer alloy can give better results with unlettered diameters.
Are you talking about controling bullet opteration with an appropriate hardness (bhn) or something else?
Hardness and length. The key feature is mass ahead of the base. So to increase obturation you increase bullet mass (more mass ahead of the base) and decrease its strength. The only way to decrease the strength is to soften the alloy. One side effect of softening the alloy is increasing the mass (more lead). This is very often a razor thin line. You can soften the alloy too much which gives leading.
Since the instant acceleration is a function of the internal pressure, this can also be used. So up the powder charge and bullets obturate. Decrease the charge and you get leading.
best thing to do is to find a happy medium. But if bullet choices are open, a heavier bullet is easier to get shooting well.
Since the instant acceleration is a function of the internal pressure, this can also be used. So up the powder charge and bullets obturate. Decrease the charge and you get leading.
best thing to do is to find a happy medium. But if bullet choices are open, a heavier bullet is easier to get shooting well.
Soft lead bullets skid and slump when fired. Not great for accuracy.
Fast pistol powders produce high pressure quickly. Not good for lead, in rifles.
In 30-06 & 30-30, i found IMR 4895 to work well with a gas checked bullet.
A filler like kapok , between powder and bullet base is not needed. Other fillers may be dangerous, if they remain in the barrel.
My pistol bullets are sized to the standards, .358, .430 & .452" for 45 acp and work well.
Rifles diameters should be 1 to 2 thousandths larger then groove diameter. Imo.
Fast pistol powders produce high pressure quickly. Not good for lead, in rifles.
In 30-06 & 30-30, i found IMR 4895 to work well with a gas checked bullet.
A filler like kapok , between powder and bullet base is not needed. Other fillers may be dangerous, if they remain in the barrel.
My pistol bullets are sized to the standards, .358, .430 & .452" for 45 acp and work well.
Rifles diameters should be 1 to 2 thousandths larger then groove diameter. Imo.
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If your bore truly is 0.317" you are going to have to go to Accurate Molds and have Tom cut you what you need. You will also have to use 8mm gas checks for that big of a bullet. Or get a 316299 from Al @ NOE Molds. Then powdercoat them a couple times to get them to the diameter you need. Accutate is my choice when it comes to custom molds.
It's not 317, that's just the high range spec in the uploaded manual pages. I have yet to slug it, but it was early/prewar production so I dont expect slop.
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