Cause for concern?

[rsvp2rip]

Just started casting for my Marlin 336w 30-30 (Rem mfr). Used 3-1 lino/COWW. 14.5 BHN. Lubed with White Label BAC. Sized .310" Lee 170gr. Finish weight is 176gr. This is as large as I can go as they drop about .3095" and they leave the .311 sizer at .310". My bore is
310" so I'm hoping it's big enough for the micrgroove rifling. My question is when I made a dummy cartridge I got light rifling engraving on the bullet almost all the way back to the case mouth, .115" off the case. It was fairly easy to chamber and didn't pull the bullet out of the case when ejected. Should I be concerned about this or just forge ahead? I'm planning on using IMR 3031 to get Max velocity around 1800 or better if possible.

[Bird]

I would try what you have first.
On your next casting session, lay out all of your bullets in order from the first bullets you cast to the last bullets you cast. Do this for maybe 20 pours. Start at your first pours and move up the line until you eliminate the wrinkled or substandard bullets, then start taking measurements from that point and to the last bullets you cast. As the mold warms up you should see a change in bullet diameters, this will give you an idea how to cast the largest diameters with your alloy.
I never saw much of a diameter improvement with your 3-1 mix. Diameters improved considerably with mixes of 1-1, or 1.5 lino to 0.5 coww.
I can get 1 thou difference in diameter, using RCBS iron mold, depending on mold temp, with plain coww. More temp= more shrinkage.
IMR 3031 should prove a good powder.
If you are getting engraving of the bullet already, you may be good to go as is.

[rsvp2rip]

I didn't really see a difference in diameter from first to last. I'm using a labratory hotplate set to 500 degrees to preheat the mould and casting pretty slowly. It was about 38 degrees in the garage so the mould wasn't getting to hot.

[Bird]

I didn't really see a difference in diameter from first to last. I'm using a labratory hotplate set to 500 degrees to preheat the mould and casting pretty slowly. It was about 38 degrees in the garage so the mould wasn't getting to hot.

Drop the temperature of the hot plate down to 100 or dont use it.

[Echo]

I never saw much of a diameter improvement with your 3-1 mix. Diameters improved considerably with mixes of 1-1, or 1.5 lino to 0.5 coww.
I can get 1 thou difference in diameter, using RCBS iron mold, depending on mold temp, with plain coww. More temp= more shrinkage.
IMR 3031 should prove a good powder.
If you are getting engraving of the bullet already, you may be good to go as is.

Hmmm - 3-1 = 1.5-.5... Just sayin'...

[Bird]

Hmmm - 3-1 = 1.5-.5... Just sayin'...

You are correct, I read it front to back.....I think I am becoming lysdexic.
First mistake, and we are only into the 13th day of the year. The OP did say 3-1 lino/coww, but a bhn of 14.5 seems a bit on the soft side for that mix. I would expect a bhn of around 17 to 18. I think that is what threw me.

[rsvp2rip]

I forgot to say I added .25lbs Canfield’s watersafe solder (4% copper, 1.5%silver, balance tin) to bring the tin up a little. I used a lead alloy calculator spreadsheet and it said 14.5 BNH should be expected. I’m not water dropping as I’m trying to get some kind of expansion on game while being hard enough to get accurate out of the Microgroove rifling, or are the two mutually exclusive?

[ABJ]

The BHN on the calculator are close, not actual. That mix will harden up about 30 plus days after casting. As far as the engraving goes, you are dead nuts on. Good support on the nose and able to unload without bullet pull. As far a size goes, like the other guys said you will just have to try and see. My marlins like .310/.311 but will shoot .309 without leading, just not as accurate.
Tony

[Wayne Smith]

Yup, shoot them as is, you are about perfect for size. DON'T start at max, of course.

[rsvp2rip]

Right on. Thanks guys.

[rsvp2rip]

Just reread my original post. I had the ratio backwards. 3 parts WW to one part Lino is what it should have been. Sorry for the confusion.

[popper]

they drop about .3095" and they leave the .311 sizer at .310". Something wrong there. Just putting on GC with the sizer? Rifling in my pre 336 is 1/4" from mouth.

[rsvp2rip]

I’m giving them a little pressure at the bottom of the stroke. Maybe the lube is giving them a .0005” extra on the mic?

[pls1911]

While 1800 fps isn't "too fast" for the alloy you're casting, don't hesitate to stop at any velocity above 1600 fps giving best accuracy in your gun.
Your hard bullets will penetrate into next week, and ballistically there's not much difference out to 100 yards.
The nice trait of the 30/30 is that it's easy to load, easy on the shooter and easy on your shootin' iron.
With proper placement, it will drop about anything you're likely to hunt with it in the lower 48.