Thursday, June 6, 2024

Converting 7.62x51 brass to 6.5 Creedmoor

I shoot a lot of 5.56x45mm and 7.62x51mm ammunition. The 5.56 is mainly used in Service Rifle Competition (although I compete less than I used to), and the 7.62 for hunting because it’s still very economical to handload and will reliably kill any large game in North America.

Years ago I put together a Swedish M41 sniper rifle clone for NRA Vintage Sniper matches, and got into the “6.5 bore” that way. A lot of my friends in the service rifle boards were extolling the virtues of the 6.5 Creedmoor as an excellent deer/antelope/competition cartridge, and I decided that if the price was right I’d get one

However, due to contentious American politics combined with the COVID pandemic, both ammunition and reloading components have been “scarce.” For my birthday two years ago I bought a 100 round bag of Starline brand 6.5 CM brass, which eventually was used building a hunting load for an Army buddy because he couldn’t find commercial hunting ammunition for less than 4 dollars per round going into that year’s deer season. I put together a basic load with a 139gr PPU brand soft point, IMR 4064, and Winchester primers, and that ended up printing five shots under an inch from his hunting rifle. He was tickled pink, and passed my “reloading recipe” on to his brother so they can replicate it in the future.

Unfortunately, that left me with no 6.5 CM brass (a truly first world problem if there ever was one), since I started getting into the caliber at a bad time. I did have bags and bags of spent 7.62x51 brass waiting to be processed, though, I figured I would give converting some into 6.5 CM a try.

I crushed and ruined a lot of cases. Despite being very similar in dimensions, this isn’t as simple as turning .30-06 into 8x57 or .30-06 into .25-06. You always pay for an education — sometimes with tuition fees, sometimes with time, and sometimes with ruined supplies — but the education and skills you get from that payment are worth it. What eventually worked with the highest conversion percentage, is this process:
  1. Clean the cases
  2. De-prime the cases
  3. Anneal the necks with a small propane torch
  4. Remove the expander ball from the resizing die
  5. Lubricate the cases
  6. Slowly size down the cases in a single stage press (this is where you’ll crush shoulders if you don’t have enough lube, or have too much lube, or go too fast)
  7. Add the expander ball back into the resizing die
  8. Lubricate the inside of the case necks
  9. Run the cases back through the resizing die enough to set the neck size to 6.5 mm (do not fully run them up since the necks are way too long at this point, you just need to open them back up enough to use the trim tool in the next step)
  10. Trim the resized cases (I use the Lee system combined with a handheld drill, works just fine)
  11. Deburr the case necks (inside and out) with a chamfer tool
  12. Tumble to remove the lube
  13. Anneal the case necks
Note: depending upon your rifle chamber, you may need a neck turning tool to decrease the outside diameter of the newly sized brass necks for safe operation at this point. I found out this brass worked fine in the LR-10 6.5 CM upper, but the necks were just a smidge too thick for the Ruger American Predator to chamber easily. Trust me that you don’t want any interference between your case necks and the chamber, as that mechanical squeeze massively increases chamber pressure. If your loads were close to top end, you’ll experience blown primers immediately.

In the end, I have 48 6.5 CM cases with the headstamp “FC 11” indicating their military surplus origins. It would have been an even 50 except I crushed a few cases learning the ins, outs, and feels of making a process that works with my tools. I also have nearly a hundred more with LC headstamps of various years which is enough to develop a decent hunting load.

The benefits of this conversion is that generally American military surplus 7.62x51 brass is consistently high quality and built to last being cycled through automatic firearms. The downside is that you often get reduced case volume because the brass is on the thick side, but that only matters to people who are looking to maximize velocity. With a 6.5 CM, or 7.62x51 for that matter, velocity is much less interesting than accuracy. If you can accurately put the bullet where you want, you can put meat on the table and score high in matches.

Now, do I recommend you go out and buy a 500 lb lot of 7.62x51 brass and do the conversion on your single stage press at home? No. In fact, unless you already have the 7.62 brass and a lot of time to do the conversion, I wouldn’t recommend conversion at all. Supplies are coming back in stock and I purchased 150 spent casings of “range brass” that netted me 104 Hornady brand 6.5 CM brass and 20 Federal brand which ended up on a buddy’s desk (hand loaders stick together!). 

I do however recommend that you run through the process enough times so that if you have to do it in the future, you can, while knowing how your dies work. The worst thing that could happen is breaking your tools without a way to replace them, in an economic disruption, while trying to learn a tricky conversion. Maybe the next “contentious political season” will cause another market disruption, and I’ll spend my weekends converting brass because I that’s the only way to have brass to shoot.

Tools Used
Press: RCBS Jr. Press (built in 1967 and still working, but nearly any press will do)
Dies: Hornady 6.5 CM dies, Lee universal decapping die
Lube: Hornady One Shot
Trimmer: Lee case length gauge and lock stud system, Ryobi brand cordless drill to spin them
Chamfer Tool: Lyman VLD chamfer tool
Case Tumbler: Lyman brand
Neck Turning Tool: K&M brand

Note: you may need to do a final sizing with a “Small Base Resizing Die” if your chamber is on the small side and the original 7.62x51mm brass was fired through a machine gun with a generous chamber; I found that about one in five converted brass had difficulty chambering in the Ruger American Predator. 

I use RCBS Small Base dies when this is necessary for my 5.56x45 service loads, and so I picked up a set for the 6.5 CM. They make chambering a cartridge from the magazine a breeze, and if you reload for a “gas gun” you’ll eventually need a small base die set to avoid chambering issues on the firing line. I don’t anticipate needing to use the SB dies for any of the loads shot solely in the Ruger since the cartridges aren’t being extracted under pressure, and so the Hornady dies will do the bulk of work for that rifle.

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