How large a diameter?

J

jski

New member
I'm reloading for my .30 Carbine Blackhawk. Of course its diameter is .308. Now, I've been told many times and repeatedly that I should use at least a .309 diameter when using cast bullets. I've also been told many times and repeatedly that I should be able to easily insert the bullet into the forcing cone at the breach of the barrel. The problem is that .309 bullets do not easily fit into the forcing cone, lest I use a hammer.

So which of the 2 pieces of advice should I go with?
 
Oh, Oh, probably disregard the following since I see now you seem to be loading for a handgun rather than a rifle and the following may not apply.


Definitely go with the .309 cast bullet and don't be concerned with the forcing cone side of it. It should only be necessary that a loaded round chambers easily but not necessarily that it does so by a "plunk" test. But you probably don't want to be chambering a live round in the loading room anyway (but try a dummy round if you'd like to confirm that the .309 round chambers properly). Size and trim the case first before completing the dummy and live rounds. For sized cases, a good size to length is around 1.286. Check your manuals for their dimensions. If you are using fired cases, the lengths will probably exceed 1.290 by several thousands after sizing.


Should have recognized from the beginning that the term "forcing cone" does not usually apply to a rifle and that a Blackhawk is a revolver.
 
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I do not know but a man asked me to remove the bullets from the barrel of his S&W State Trooper. He had 6 jacketed bullets stacked in the barrel and all he needed was the bullets removed and he could go back to shooting.

In his effort he expanded the forcing cone .011", I still have the barrel and he is back to shooting.

F. Guffey
 
I'd go with .309 unless the bullets won't chamber.

When you say the bullets won't fit into the forcing cone did you mean the cylinder throats? The ideal fit for a bullet is a tight fit in the cylinder throats. Too small will probably cause leading and too large cause problems with being able to chamber the rounds.
 
If a bullet fits into the forcing cone, then it is too small.

You should measure the throats of the cylinder. You can get close with a dial caliper.

If the throats do not measure consistent between each other, do not expect stellar accuracy.

If they do measure consistent between cylinders, then select a bullet diameter that is a snug fit in the cylinder throats and completely disregard any bullet fit in the forcing cone advice.
 
Reddog81
I wouldn't think the OP is referring to the cylinder throats, but rather to the approach to the lands in the barrel in which case he would be correct. He can confirm if that is what was meant. His reference to having to use a hammer would suggest the forcing cone.
 
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Have .30 Carbine handgun data(pretty much the same as long gun data anyway) in a Lyman pistol and revolver manual. No mention of using a .309" cast bullet. I'd have to check to be absolutely sure though. Not at home.
One thou isn't going to make a lot of difference to anything though.
 
In a revolver the lead bullet has to fit in the cylinder throat. The forcing cone on a revolver is like the leade area of the rifle chamber. As long as the .309 bullet will slide into the front of the cylinder (barrel end) it should be fine.
 
With the headspacing at the case mouth and the tightening of the cylinder throats, I was forced to push the .309 bullet deep into the case ... maybe too deep ... to get it to seat properly in the chamber. It would certainly constitute a compression load.

I used the 50 .309 diameter bullets I had and called Montana Bullet Works and changed my order to .308.
 
What load are you using? With H110 or 4227 powder, a compressed load would be normal. What is the AOL you end up with and how do you anticipate that a .308 bullet will be an advantage over the .309? I think I recently checked Montana Bullet Works for carbine bullets and the only ones I could find had a crimp groove that isn't usual for carbine loading. However did your .309s have a crimp groove?
 
I was using 14.5 gr of H110. The actual bullet is 115 gr hard cast, gas checked:
DSC3241-2-308_RCBS_115GR._RN-GC-270x340.jpg


Taper crimped.
 
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I would assume that your revolver rounds headspace on the case mouths, same as for the rufle. Since those bullets do have a crimp groove, carbine lead bullets normally don't, it would probably be best to avoid crimping in the groove. With bullets not having grooves, the standard procedure is to apply just enough taper crimp to remove any flare from the case mouths. Perhaps try seating bullets just above or below the groove, apply a mild taper, and see how the overall length turns out. Montana Bullet Works is great for cast bullets, have purchased thousands from them, but turned down the 115 gr due to the grooves. Instead recently purchased Hunters Supply brand from Midway. The 14.5 H110 is a good load.

Since the MBW bullets are lubed and gas checked, my guess is that they are intended for rifles other than carbines.
 
My intent was/is to leave the groove just outside the case. This was not possible with the .309 bullets. When I tried this the bullets/cartridges wouldn't seat properly... they protruded well above the cylinder.

Are there any issues using this bullets? Of course, I mean the .308 diameter bullets.
 
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I would suspect the 0.308" diameter bullets will be too small for good accuracy and will probably leave some lead in the barrel, gas check or not. The gas check will aid in that department.
 
My guess is that the .308s will be the same length, just .001 less in diameter, so the groove will be in the same location as on the .309s. Probably will encounter the same seating problem. Often lead bullets for the carbine do not have gas checks, usually only one lube groove, and no crimping groove. Strange that MBW does not have a standard carbine bullet. The .308 diameter should be fine. I have some .307 jacketed pull down military carbine bullets.
 
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Dufus, I would have needed a hammer to push that .309 bullet thru the cylinder. That can't be the better size v. the .308 !
 
I stand corrected. I missed the part that stated you had trouble with the 0.309" in the cylinder throats.

Go make some noise and happy shootin'.

Some times the throats are smaller than the bore, in which case it would be prudent to enlarge the throats to a thousandth or so larger than the bore.

I had to do that to two of my chamber throats on one of my SBH to get them as close as possible.
 
A slight force fit with a cast lead projectile isn't a bad thing. .309 should be fine. Probably preferred to reduce leading and increase accuracy. If the caliber calls for a certain diameter with a jacketed projectile, a lead or cast projectile .001 over that size is fine as long as the gun is in spec. Slug your barrel. You really should do that anyway before ordering bullets.
 
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