Sizing Question

[texaswoodworker]

Howdy.

I cast bullets for 7.7 Japanese using a .312 mold. It typically casts bullets between .312 and .315 depending on the alloy I use. I'm also wanting to cast bullets for 30 caliber, but haven't invested in a mold for 30 cal yet. I have a .309 sizing die that I use for pistol bullets. Is there any reason why I couldn't just size my 7.7 Japanese bullets to .309? It seems like it would work just fine, and would save me from having to buy another mold right now. (going back to college, so money is tight)

Thanks

[Tatume]

The first thing you should try is 0.312" bullets. If the loaded ammo will chamber it will be safe to fire at reasonable pressures. Load a dummy round and try it.

Second, there is no reason not to size your bullets to 0.309" if that is what is needed. Be sure to lube them first though. Otherwise the lube grooves may be obliterated.

One of the outstanding values in the world of shooting is the Lee C309-170-F:

http://www.midwayusa.com/product/574963/lee-2-cavity-bullet-mold-c309-170-f-30-caliber-309-diameter-170-grain-flat-nose-gas-check

The bullets are very accurate, and the mold only costs $20.

What will you major in when you get back to school?

Take care, Tom

[texaswoodworker]

The first thing you should try is 0.312" bullets. If the loaded ammo will chamber it will be safe to fire at reasonable pressures. Load a dummy round and try it.

Second, there is no reason not to size your bullets to 0.309" if that is what is needed. Be sure to lube them first though. Otherwise the lube grooves may be obliterated.

One of the outstanding values in the world of shooting is the Lee C309-170-F:

http://www.midwayusa.com/product/574963/lee-2-cavity-bullet-mold-c309-170-f-30-caliber-309-diameter-170-grain-flat-nose-gas-check

The bullets are very accurate, and the mold only costs $20.

What will you major in when you get back to school?

Take care, Tom

I'm going back to finish my degree in mechanical engineering. :)

The LEE molds are what I use. The particular one I'm using is the .312-185-1R. I'm just trying to make sure I have all my school stuff settled before I buy more supplies.

I ran a few through the sizer. The lube grooves look good, and the bullets are at 189gr with the gas check. Some of my favorite loads out of my 30-06 are 180gr, those these should hopefully work well too.

Thanks. :)

[ukrifleman]

I don't see why not, I size gas checked Lee 175gn 8x57 Mauser bullets, down from .323 to .314 for use in my Lithgow .303.

I use Liquid Alox lube and a Lee bullet sizing die and it works fine, I just have to re-lube them after sizing down.

ukrifleman.

[williamwaco]

You can go from .312 to .309

I occasionally size .38 special bullets from .361 to .356 for the 9mm. Works fine.

That said,

If they will chamber easily, I would try the .312's first.

I always size my .30 caliber bullets to .311 ( which really mikes around .3113 to .3116 )

[Tatume]

PM sent.

[jonk]

Wow, I can't believe I'm poster #7 and no one has stated the obvious.

This gentleman is obviously new to the hobby and sport of casting, at least for rifle, and everyone's saying "Sure, size down, have at."

No.

I know Lee markets their 185-.312 as suitable for .303, 7.7, etc., but in practice, it's usually too small in diameter. It's rare that I find a fat .30 like these that is truly a .311 bore; you want to cast a bullet that measures 1/1000 to 2/1000 OVER groove diameter. The best way to determine that is to slug your barrel with a soft lead slug, and go from there. With the Jap and its Metford style chromed rifling, that could be hard, and I'd encourage you to instead measure a fired case inside neck diameter, and go with a bullet that is just slightly under that diameter. So if the case measured .315, I'd go with a .314 bullet for instance. That way the bullet will fit the neck and hopefully the throat.

If you fire a bullet too small in diameter, you're sure to encounter leading and poor accuracy.

Sizing to .309 in a gun meant for a .312" bullet (and often requiring an even fatter one) is going to get you nowhere fast.

Now, if you have an abnormally tight Jap 7.7 that slugs at .307-8- and such wouldn't surprise me much, then sizing to .309 would be just fine.

Try the mold as cast first. If you don't have a sizer for .312, just superglue the gas checks to the shank of the bullet, or just kiss them into your .309 die and then remove. If they shoot, then order a .312 sizer.

I still think you will find though, that the bore on that gun measures something like .315, .316, something like that, and you will need to either fudge your existing mold to accomodate that, order a new one, or size down a larger boolit like the Lee .323 model.

[whisler]

His original post states that though he now cast for 7.7 Jap etc., he wants to cast for 30 cal. also (which I took to mean 30-30, 308, 30-06 etc.) and wants to know if he can size down the bullet he uses for 7.7 Jap. Am I missing something?

[emrah]

Doable but beware the lube groove elimination someone mentioned earlier. If they're gone, pressures may spike.

Emrah

[dondiego]

More than likely he will be able to shoot them as cast with no sizing in all of his 30 cal. rifles.

[texaswoodworker]

Wow, I can't believe I'm poster #7 and no one has stated the obvious.

This gentleman is obviously new to the hobby and sport of casting, at least for rifle, and everyone's saying "Sure, size down, have at."

No.

I know Lee markets their 185-.312 as suitable for .303, 7.7, etc., but in practice, it's usually too small in diameter. It's rare that I find a fat .30 like these that is truly a .311 bore; you want to cast a bullet that measures 1/1000 to 2/1000 OVER groove diameter. The best way to determine that is to slug your barrel with a soft lead slug, and go from there. With the Jap and its Metford style chromed rifling, that could be hard, and I'd encourage you to instead measure a fired case inside neck diameter, and go with a bullet that is just slightly under that diameter. So if the case measured .315, I'd go with a .314 bullet for instance. That way the bullet will fit the neck and hopefully the throat.

If you fire a bullet too small in diameter, you're sure to encounter leading and poor accuracy.

Sizing to .309 in a gun meant for a .312" bullet (and often requiring an even fatter one) is going to get you nowhere fast.

Now, if you have an abnormally tight Jap 7.7 that slugs at .307-8- and such wouldn't surprise me much, then sizing to .309 would be just fine.

Try the mold as cast first. If you don't have a sizer for .312, just superglue the gas checks to the shank of the bullet, or just kiss them into your .309 die and then remove. If they shoot, then order a .312 sizer.

I still think you will find though, that the bore on that gun measures something like .315, .316, something like that, and you will need to either fudge your existing mold to accomodate that, order a new one, or size down a larger boolit like the Lee .323 model.

My Arisaka has a .314 bore (if I measured it correctly. As you said, it's not easy to measure the bore of an Arisaka), and the alloy I'm using comes out at .315, so I'm good there. The sizing down is for my 30-06. :)


His original post states that though he now cast for 7.7 Jap etc., he wants to cast for 30 cal. also (which I took to mean 30-30, 308, 30-06 etc.) and wants to know if he can size down the bullet he uses for 7.7 Jap. Am I missing something?

You are correct sir.


Doable but beware the lube groove elimination someone mentioned earlier. If they're gone, pressures may spike.

Emrah

Occasionally, a lube groove may be somewhat distorted, but most come out clean so far. I sized about 20 bullets just to test them in my rifle.


More than likely he will be able to shoot them as cast with no sizing in all of his 30 cal. rifles.

My plan is to try a few different sizes and a few loads for each size to find out exactly what works best in my rifle. I've got a few .309s loaded up. Hopefully I can get out to the range and test them soon.

Thanks for the help everyone. :)

[emrah]

FYI, I size a .318 mold down to .3155 for my Arisaka