Since jacketed bullets have been covered well ( I voted for the Speer .308 -170 grain), here is a specific recommendation for cast bullet mold design for the 30-30, from Arsenal molds. They are "Ranch Dog" design. "Ranch Dog" is the handle of a contributer from castboolits.com, who designed it specifically to work in Marlin rifles. The key design elements: maximum meplat for energy transfer, and max bullet diameter for good throat fit/ groove diameter gas seal. Available in "standard" lube grooves, and micro/tumble lube band design.

Arsenal Molds have an added benefit, that at no additional charge, you can specify the bullet diameter for best throat fit of your rifle-for best accuracy. Excellent quality, and high value. Also available in gas check /no gas check options or combo molds ( nice option for low cost shooting). Highly recommended. If you don't have a lube/sizer ( and lube sizer dies ... $$$), you can due VERY well with the tumble lube design.

http://arsenalmolds.com/products?product_id=107&limit=100

http://arsenalmolds.com/products?product_id=84&limit=100
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You can get a push through sizer ( with diameter bushing choices ) from Night Owl Enterprises (NOE molds), and either pan lube, then size, or use as a gas check seater ( less $ than expensive set up with lubesizer and dies). NOE also makes excellent molds, carries the Ranch Dog design in standard and micro-band, but they are often out of stock.

https://noebulletmolds.com/site/product-category/bullet-casting-reloading/sizing-tools/

For best accuracy, get a good measurement of your chamber's throat (do an internet search for "pound cast" method), and get a bullet diameter just a smidge smaller ( so it enters/ fits), like 1/2 thousanths".
With the high cost and limited stock of jacketed bullets, a simple cast bullet system may make sense. A big meplat mold design of proper diameter with a plain base bullet combo ( with also gas check version) with a micro-band ( no expensive equipment) could be a way to overcome bullet supply issues, while being an accurate, deer-focused hunting design.

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