.30 Carbine Bullet Diameter?

jski · June 29, 2021, 12:35 PM

I reload a lot for my .30 Carbine hogleg (Ruger Blackhawk). I’ve always used a .308” diameter bullets but I thought I’d try a .309” diameter bullet this time. So I ordered a batch of .309” diameter bullets from Montana Bullet Works.

When I got my .309” diameter bullets, I tried pushing them thru the cylinder. They wouldn’t go thru without a chopstick I sometimes use plus some gentle tapping (using a mallet) on the chopstick. The .308” just needed an ever so slight push (no mallet) from the chipstick.

Both when loaded into a cartridge sit equally well in the cylinder. But which is better? Which is preferable?

jski · June 29, 2021, 12:40 PM

Keep in mind that the chamber diameter in the hogleg cylinder has an abrupt change as it goes further in. This is because the .30 Carbine is rimless and hence headspaces on the case mouth.

Geezerbiker · June 29, 2021, 12:45 PM

I'd say the ones that shoot the best groups are the ones to use. An extra .001" won't be a problem on a cast bullet at firing pressures.

Tony

**44 AMP** · June 29, 2021, 12:50 PM

Keep in mind that if the round is properly (fully) seating in the chamber, the bullet is past the ledge the case mouth stops against.

Larger bullets get "squeezed to fit", and you're only talking a very small amount, which MIGHT even be within the tolerance range of your gun.

gwpercle · June 29, 2021, 02:22 PM

In theory .309" should be the "proper " size for a cast lead bullet , .001" over the jacketed bullet size of .308" .
The .309" are a nice snug fit in the throats ... that's good , so everything looks like .309" will be better / preferable ... But ...there's always a but ... the only way to tell is to load up a test batch and do what the ole gator hunter Troy Landry says to do ...Choot Em !
Your gun will tell you what it likes ...and revolvers are like wives ... you gotta keep em happy happy .

I have one 45 acp revolver that isn't happy unless I size cast bullets .451" ...if I size them .452" like my 1911's ... she wont chamber them at all ...so I let her pick what she likes.
Gary

June 29, 2021, 12:35 PM	#1
jski Senior Member Join Date: March 5, 2016 Posts: 374	.30 Carbine Bullet Diameter? I reload a lot for my .30 Carbine hogleg (Ruger Blackhawk). I’ve always used a .308” diameter bullets but I thought I’d try a .309” diameter bullet this time. So I ordered a batch of .309” diameter bullets from Montana Bullet Works. When I got my .309” diameter bullets, I tried pushing them thru the cylinder. They wouldn’t go thru without a chopstick I sometimes use plus some gentle tapping (using a mallet) on the chopstick. The .308” just needed an ever so slight push (no mallet) from the chipstick. Both when loaded into a cartridge sit equally well in the cylinder. But which is better? Which is preferable?

June 29, 2021, 12:50 PM	#4
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 30,479	Keep in mind that if the round is properly (fully) seating in the chamber, the bullet is past the ledge the case mouth stops against. Larger bullets get "squeezed to fit", and you're only talking a very small amount, which MIGHT even be within the tolerance range of your gun. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

June 29, 2021, 12:40 PM	#2
jski Senior Member Join Date: March 5, 2016 Posts: 374	Keep in mind that the chamber diameter in the hogleg cylinder has an abrupt change as it goes further in. This is because the .30 Carbine is rimless and hence headspaces on the case mouth.

June 29, 2021, 12:45 PM	#3
Geezerbiker Senior Member Join Date: March 20, 2011 Location: Willamina, OR Posts: 1,909	I'd say the ones that shoot the best groups are the ones to use. An extra .001" won't be a problem on a cast bullet at firing pressures. Tony

June 29, 2021, 02:22 PM	#5
gwpercle Senior Member Join Date: November 30, 2012 Location: Baton Rouge, Louisiana Posts: 1,915	In theory .309" should be the "proper " size for a cast lead bullet , .001" over the jacketed bullet size of .308" . The .309" are a nice snug fit in the throats ... that's good , so everything looks like .309" will be better / preferable ... But ...there's always a but ... the only way to tell is to load up a test batch and do what the ole gator hunter Troy Landry says to do ...Choot Em ! Your gun will tell you what it likes ...and revolvers are like wives ... you gotta keep em happy happy . I have one 45 acp revolver that isn't happy unless I size cast bullets .451" ...if I size them .452" like my 1911's ... she wont chamber them at all ...so I let her pick what she likes. Gary