Looking for .316

[DHB]

I quit casting probably 30 years ago. I now NEED a strange thing. I need a .316 bullet preferably at 165 grains. I picked up a Cadet Martini that has a Marlin 32-20 barrel on it. That would be no problem but the barrel is chambered in 32-40. 32-40 is different bore size than 32-20. So I need some .316 bullets. A jacketed 312 will fall through, a cast .314 will push through with very little resistance. So I am looking for commercial .316
Please help.
DHB

[Bigslug]

You're probably looking for something bigger than .316". A tight push through is going to be your BORE diameter; GROOVE diameter will be larger. For comparison, .308 Winchester is usually .300 bore / .308 groove. .303 British - usually .301 to .303 and .312 to .315 - sometimes larger.

Guessing you MIGHT be running a .323/8mm barrel (which would be lucky), but you're going to need to slug it to be sure.

[Bigslug]

You're probably looking for something bigger than .316". A tight push through is going to be your BORE diameter; GROOVE diameter will be larger. For comparison, .308 Winchester is usually .300 bore / .308 groove. .303 British - usually .301 to .305 and .312 to .315 - sometimes larger.

Guessing you MIGHT be running a .323/8mm barrel (which would be lucky), but you're going to need to slug it to be sure.

[pworley1]

The lyman 321317 should work.

[Bad Ass Wallace]

If you have a Marlin 32/20 barrel then the bore should be 0.312" and the correct diameter required 0.314" despite the 32/40 chambering. Replace the expander in the die set with one of 0.310". I think the 32/20 Marlin twist may not stabilise a boolit over 130gns.

If you still want a 165gn 0.316" boolit, I can recomment this one from Cast Bullet Engineering.

https://www.castbulletengineering.com.au/products/rifle-moulds/31-cal-and-32-20/product/799-316-175gc

[Fitz]

NOE also has a good selection of moulds in .316

[challenger_i]

When working with a Cadet that had been "converted" to 32-20, I used the RCBS 8mm Nambu cast bullet (.321" as cast). I ordered a sizing die from Lee that sized the 321" pill to .318". Made a tack driver of the Cadet.
Using a .321" 8mm mold and a sizing die for your bore/groove dimensions may be an option for your application.

[MostlyLeverGuns]

If your barrel truly is/was a 32-40, bullet diameter should be .320-.323 depending on chamber set up. The real question - is the barrel really a .32-20 diameter which is .312 +/- or is it a .32, which is probably .320/.321? Many .310 Martini Cadets were re-chambered from .310 Cadet to .32-40 or .32 Winchester Special as the original barrel is .323 +/-. Some might have been re-chambered to 32-20, but then a .323 bullet would be needed for any kind of accuracy.

[405grain]

You're not going to know for sure what you need until after you slug the bore. Find out exactly what the land/groove diameters are and it will remove all the guess work.

[DHB]

THANKS FOR ALL THE IMPUT!
Don't forget guys the barrel is from an early Marlin. The bore slugs at a grove diameter of .312 The barrel is chambered in 32-40. I did a chamber cast too. A .312 jacketed bullet falls all the way through the bore by it's own weight. A .314 pushes through with a 1/4 inch dowel. I have already ordered a .316 bullet sizer. I have some of Bear Creek Supply's wonderful 310 Cadet bullets that I use in a Martini that was chambered to 32-20. They work wonderfully in THAT Martini. This is a Marlin barrel I'm talking about here. When the sizer arrives I will use the BCS bullets in the sizer and try them out. I was just looking for another bullet source. I really, really don't want to start casting again.
Thanks
DHB

[megasupermagnum]

That makes no sense. If your groove diameter is .312", a .312" bullet can not fall through, not by a long shot. Are you mixing up bore and groove diameters? If your bore is .312", your groove should be ballpark .321" or .322". Since you say you did a chamber cast, what does your throat measure?

[Bigslug]

That makes no sense. If your groove diameter is .312", a .312" bullet can not fall through, not by a long shot. Are you mixing up bore and groove diameters? If your bore is .312", your groove should be ballpark .321" or .322". Since you say you did a chamber cast, what does your throat measure?

Yeah. What he said.

I also have a .32-20 (ish) rechambered BSA Martini. The groove diameter of that rifle is .3185" and I've shot both a .320" sized and a .321" tumble lube bullet. I forget what pin gauge was needed for a slip-fit through the bore, but conventional British cartridge nomenclature would suggest it was close to .310".

Short version - if you can push a .314" bullet through your barrel's smaller BORE diameter without a mallet, .316" is going to be significantly too small to correctly fit the larger GROOVE diameter.

You need to slug the barrel with an oversized, pure lead article pounded through with a close-fitting steel rod strategically wrapped in several places with masking tape. Use a shorter chunk of the same rod to get it started. If you have a soft lead 158 grain .38 revolver bullet pulled from a factory load, that would work perfectly. That will give you your groove diameter, and your functioning bullets will want to be sized .001" to .002" over that.

Guessing that you're going to end up needing a bullet that's between .321" and .324".

[Bad Ass Wallace]

guessing that you're going to end up needing a bullet that's between .321" and .324"


I picked up a Cadet Martini that has a Marlin 32-20 barrel on it

I say again, you must be mistaken about the origin of that barrel?

[MostlyLeverGuns]

The 32-20 and 32-40 are significantly different cartridges with large difference in BOTH bore size and case size. The 'standard' bore/groove measurement of the 32-20 is .308/.312 plus/minus while the 32-40 bore/groove diameter is .316/.320 plus/minus. A 32-40 barrel needs a bullet .320 to .323 in most cases, the 32-20 usually works best with .312 to .314 bullets. No offence meant, but something sounds wrong in your description or measurements.

[DHB]

Running a slug through the barrel and measuring the parts that stick out (groves) it measures .312. Why a jacketed .312 falls through I don't know. I don't know what happened to the slug to check. Maybe it is an odd number of lands & groves. The slug measured .312, but a jacketed just falls through. The 1st jacketed I tried was a Speer, the 2nd was a Hornady 85gr and it also just fell through by its own weight. The throat measures .314-.315.

[DHB]

The barrel is octagon and is stamped "Marlin Firearms Co New Haven USA" + patent dates and in another spot "Special Smokeless Steel" so it is definitely a Marlin barrel. There is also a "grove" similar to the barrel on a lever action or pump rifle to allow the magazine tube to fit into the action below the barrel.

[megasupermagnum]

Running a slug through the barrel and measuring the parts that stick out (groves) it measures .312. Why a jacketed .312 falls through I don't know. I don't know what happened to the slug to check. Maybe it is an odd number of lands & groves. The slug measured .312, but a jacketed just falls through. The 1st jacketed I tried was a Speer, the 2nd was a Hornady 85gr and it also just fell through by its own weight. The throat measures .314-.315.

I'm still thinking you messed up somewhere, but if what you say is correct, a .316" bullet still isn't what you want. A .314" or .315" is what you want. That's inline with a lot of 32-20's. It still doesn't explain the .312" bullet falling through. A 32-20 bore should be ballpark .304"-.305", and thus even a .308" 30 caliber bullet could not fall through one.

[Bad Ass Wallace]

There is also a "grove" similar to the barrel on a lever action or pump rifle to allow the magazine tube to fit into the action below the barrel.

Well there is the problem, there is no groove to fit the magazine tube on genuine Marlin barrels?

[MostlyLeverGuns]

I have several Marlin factory barrels, 1893,336, 444 and many Marlin rifles, there is a 'relief' on the bottom of the barrel near the receiver for the magazine tube. It is hidden by the fore end but the 1893, 36, 336, and 444 have it, pretty sure the modern 1895 45-70 has it too but you must pull the fore end to see it, do not know about the 1894 or others. Just checked a few Marlin barrels, it is a shallow relief cut that extends 5.5" to 8" up the barrel from the threads.

[DHB]

I said grove, relief is a better word. I used the word grove because the "relief" is slightly rounded as it extends up the barrel. It does extent up the barrel 5-7,8 inches.

[ulav8r]

Oh, you meant groove. If a .312 bullet falls through and a .314 can be pushed through easily, then your bore diameter is about .313 +/- and the groove diameter should be about .321. Look for a bullet diameter of .323, then size down to .001 under measured throat diameter.

[Wilderness]

The barrel is octagon and is stamped "Marlin Firearms Co New Haven USA" + patent dates and in another spot "Special Smokeless Steel" so it is definitely a Marlin barrel.

There's your answer - "Special Smokeless Steel" will be .32-40. The other version was "for Black Powder Only". This distinction was made for .32-40 and .38-55 barrels for the M1893. Never heard of it on M1894 (.32-20 etc).

My Marlin .32-40 (Black Powder barrel, about 1916) will just engage a .314" bullet, and shoots well with .321" and 323".

Edit: In the days of paper catalogs, Numrich were specialling off Marlin 1893 barrels in .32-40 and .38-55. Evidently they sold the "Special Smokeless Steel" ones first, then the black powder ones. The one I got was black powder. I'd be punting that your barrel is one of the Numrich specials. Turning it into a martini barrel would require cutting off all the threaded portion (square threads) and rethreading (V threads), then rechambering. The original caliber marking on the top of the barrel will have disappeared under the new threads.

[Larry Gibson]

Your barrel apparently has an odd number of lands and grooves. Cut a strip from a soda can 1/2" wide by 2 - 3" long. Measure the thickness, should be close to .004(?). Wrap it around the slug you drove through the bore and pinch it tight. Measure the outside diameter of that and subtract twice the thickness of the pop can strip. That will give a more accurate measurement.

Also, are you saying you have a Marlin barrel that was originally a 32-40 but has been set back, installed on the Martini action and then chambered in 32-20?