30 Cal RUSSIAN -VS- 308 (Differences Explained)

Have you ever compared cartridges like 7.62x39mm and 308 Winchester and thought to yourself: What is up with 0.308″ -vs- 0.312″ ??? I definitely have! In this article I’ll look at the differences between these two caliber conventions (30 cal Russian versus 308) and talk about interoperability between the two for reloading.


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30 Call Differences and Similarities (Russian -vs- 308)

As outlined in the video, it’s helpful to look at two things when comparing these calibers!

Bore Dimensions, Bullet Dimensions

Above you see the diagram I drew for the video, and in the diagram we have some key differences, and some similarities as well!

Here’s a breakdown of the data in the diagram above:

And bullet diameter is a bit more simple:

  • 308 is typically exactly 0.308″
  • 30 Cal russian ranges from 0.311″ – 0.312″ (can vary more than that)

Reloading Interoperability Between 30 Cal Russian and 308 Cartridges

Above: Loading 7.62x39mm on the Hornady Lock-N-Load AP 5-station progressive reloading press

Different cartridges will require different components (such as which powder is used, specific to the cartridge loaded, and the weight of bullet used). But one question that gets asked a lot is: “Can I use 308 bullets for [Russian 30 cal cartridge]” (and vice-versa).

The guidelines are pretty simple: (keep in mind disclaimer near the top of this article)

  • It is generally safe to load 30 Caliber Russian cartridges using 0.308″ diameter bullets. Some degradation of velocity may occur.
  • It is generally NOT SAFE to load cartridges that use a 0.308″ bullet with bullets larger in diameter- such as 0.311″ and 0.312″ bullets.

If you do load for 0.308″ groove-diameter barrels with oversize bullet (such as 0.311″ and 0.312″) you risk unsafe high pressures, and possible damage to your rifle and/or yourself. Don’t risk it!

Above: Reloading components for 7.62x39mm: Berry’s 123 grain spire point bullets, Hodgdon CFE-BLK, and Capital Cartridge once-fired cases.


The good news from the guidance laid out in this article is: 0.308″ bullets are safe to use in both 0.308 cartridges and in 30 cal Russian cartridges. These 0.308″ bullets are readily available, and you’re likely to find exactly what you need for your loading application. You *may* experience degraded accuracy when loading 0.308″ bullets for 30 caliber Russian rifles, but in come cases, accuracy can be exceptional for this scenario.

Special thanks to Fred Zeglin from 4D Reamer Rentals for his help putting together this story! If you want to support him, there are a couple ways to do so here:

Visit 4D Reamer Rentals

If you are looking to rent chambering reamers or other gunsmithing tools, look no further than Fred Zeglin’s 4D Reamer Rentals!

From 4D Reamer Rentals:

We have over 1500 chamber reamer rentals in stock and ready to ship. We also rent headspace gauges and many other gunsmithing tools. Our tools are well maintained and inspected before and after each rental to assure you receive the highest quality gunsmithing tools. Our staff has over 35 years of professional gunsmithing experience, setting us apart from the competition.

Gunsmithing Books from Fred Zeglin

If you are looking to learn more about gunsmithing, and want to learn from one of the best, you’ll want to check out the books and other resources from Fred Zeglin.

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