30-30 to 6mmBRM

[roysclockgun]

A few years back, I bought an E. Brown Inc. rifle in 6mm Bench Rest Magnum. The wildcat case is 30-30 Win. I have to neck down with 7mmWaters, then with the 6mmBRM die to get cases. These must be fire formed. Good news, pressures are low, so the formed cases last a long time.
Recently I got two boxes of 30-30 cartridges for free. I have never owned a 30-30 chambered firearm, so I thought of pulling the bullets and necking them down to 6mm, but leaving the propellent charge alone. The 6mm bullet only weighs 100gr., while the Remington 30-30 bullet is 170gr.
Anyone see any problem with my swapping out the bullet and leaving the propellent load as it is?
Steve Ashe

 

[Guest]

I'd be awful careful about that, as you have no real knowledge of what the powder actually is in those loads. I'm sure it's something akin to BL-C(2)/Win748/IMR4895/Acc2520, but that's kind of a broad range and might not be useful. If it's just 40rds, you're only talking about maybe a $3-4 worth of powder to fireform these brass if you dump what's in there.

 

[onesonek]

Dump the powder, you have no idea of whats what otherwise. I'm nearly positive what is in that 30-30 170 gr. load is going to be different than needed than wanted or needed for the 6mm 100 gr. load, in that much change in caliber of roughly the same capacity. If you knew the powder for sure, and change the charge weight accordingly, you may get by, but why risk it for so little savings. And yep, that 6mm will be better with something of at least 4350 or slower class of what Dub mentioned posisble in there behind the .30/170's. It aint worth the risk to body or gun for a couple bucks.
They are pretty darn nice efficient chamberings, every one of the branding. I do have the 7 myself, and gave the 6 some serious thought as well, just because I like rimmed rounds in certain rigs and situations.

 

[Oldtrader3]

Steve, cartridge pressures are to a great extent based on the case capacity to bore ratio. What this means is that as you reduce the bore this ratio gets increases and gets high pretty fast as does the pressure of the load with the faster burning powder of the .30-30. Throw the old powder out and start from scratch with a loading manual or with Powley's Computer to find the correct load for this case/bore combination.

 

[roysclockgun]

I will heed all of that counsel.
Thank you,
Steve Ashe