.30 Carbine Bullet Diameter?

[jski]

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?

 

[FROGO207]

For lead bullets one thousands over the size of jacketed is the rule of thumb. In mine .309 shoot well after I reamed the throats in both of my 30 Carbine Blackhawks. You should slug your bore and throats first. Determine that the throat is .001 larger than bore and you have no restriction in the bore where the barrel screws into the frame. Otherwise you will have poor accuracy and leading. With jacketed bullets you dont have to be nearly as fussy.

FWIW I have had to ream at least one of the cylinders of all my revolvers to get them to shoot lead bullets well no matter the brand. But none have cost me more than 1K either.

 

[reddog81]

Sounds like both should work. I've had best luck with bullets that need a slight push to get through. Bullets that are .001 oversized seem to work just fine also. Bullets that just fall through are too skinny while bullets that need substantial force are too wide.

When using lead bullets too small in diameter is a recipe for poor accuracy. Jacketed bullets seems to be less affected.

Another important factor is that all the throats are the same size. Additionally, If the groove diameter is larger than the throats than you're kind of in a dilemma unless you're willing to get the throats opened up.

There are a number of considerations. Sometimes it's just best to load em up and see if there's any noticeable difference in accuracy.

 

[jski]

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.

 

[jski]

For lead bullets one thousands over the size of jacketed is the rule of thumb. In mine .309 shoot well after I reamed the throats in both of my 30 Carbine Blackhawks. You should slug your bore and throats first. Determine that the throat is .001 larger than bore and you have no restriction in the bore where the barrel screws into the frame. Otherwise you will have poor accuracy and leading. With jacketed bullets you dont have to be nearly as fussy.

FWIW I have had to ream at least one of the cylinders of all my revolvers to get them to shoot lead bullets well no matter the brand. But none have cost me more than 1K either.

Reaming the chamber throats? When the cartridge headspaces on the case mouth? Isn’t that risky? Couldn’t you reduce that ledge used for headspacing to a dangerously narrow ledge?

 

[FROGO207]

One had a cylinder that was .307 and the other had two that were about .3075. One had a slight restriction where the barrel screwed in. I used valve grinding compound on the bullets to smooth the chamber out by shooting. It took about 85 rounds to do that. I also had to polish all the chambers or the full power FMJ/jacketed loads would stick in both revolvers. Still have to clean the cylinders after 3-4 times through or the ammo will not fully seat in the chambers. FWIW I do not have this problem with any of the 357/9MM convertibles. Just had to enlarge a number of the throats on those.

 

[GooseGestapo]

With a .311” bullet, my .30Carbine BH will require ammo loaded with USGI BRASS to be pushed into the chambers. Loaded with .308” jacketed, they just drop into the cylinder.

I’ve currently loaded some .308-.309” cast and they just drop in. Next range trip I’ll see how they shoot. .311” in commercial brass shoots better than jacketed FMJ.

93gr Lee RN cast from 6-cav mold and powder coated with Harbor Freight PC shoot marvelously. I just bought a MidwayUSA Inland carbine. It shoots FAR better than my Saginaw SG.
Will see how cast performs.

 

[jski]

Are Berry’s bullets considered good slugging material? They’re soft lead with a thin copper plating. All my other 30 Carbine bullets are hard cast which makes them completely inappropriate.

 

[FROGO207]

Never have tried them so don't know. I use a pure lead bullet, round ball, or an old fishing sinker. If it is just the size put it on a hard surface and hit it on the point/top to mushroom it out a bit to make sure it fills the bore completly.

 

[edwardware]

For cast bullets, the throat must not undersize for the bore.

After that, it's good if the throat isn't loose (bullet doesn't fall through).

And third, it's best if the bullet can be pushed, not pounded, through.

It's sounds like yours fit perfectly.