.32 Remington bore slugging, boolit sizing question

[texassako]

I slugged the barrel of my Remington Model 8 in .32 Remington, and ran into issues I have not dealt with before. It is a 7 groove barrel with narrower lands(~.05") than I am used to seeing; so I spun the slug in a caliper and also used shim stock around the slug coming up with .3195". I can't get into the lands portion of the slug with my tools to measure that part. I have heard before that Remington made these with tighter than you would expect bores. What should I size boolits to considering the tight bore and tiny lands? .320 or .321? I use Lee push through dies to size custom fit by myself from a standard offering.

[Harter66]

I worked in a model 14 in 32 Remington. Like yours its tight but is a 6 groove at 3205. I shoot a 325-175 plain based boolit in it run through a 323 Lee push through sizer. I lube w/a modified Darrs lube and IMR4350 . I actually am able to run that faster than a jaxeted cousin.

My Boolits are true sized to 323 and feed freely.

[runfiverun]

cheat a little and measure inside a fired case.
this will give you a body diameter maximum to work from.
the nose area is the part you are gonna have to sweat depending on the design you go with.
i'd use the bottom of my caliper to see what my land height is then subtract for the nose diameter/bore ride part of the boolit.

[texassako]

cheat a little and measure inside a fired case.
this will give you a body diameter maximum to work from.
the nose area is the part you are gonna have to sweat depending on the design you go with.
i'd use the bottom of my caliper to see what my land height is then subtract for the nose diameter/bore ride part of the boolit.

I never thought about measuring the inside of a fired case. I have not decided on a mold design yet as measuring for the nose was giving me problems. The bottom of the caliper is a bit to thick to fit where the lands left an imprint, but I guess I could file it a little since it is not a high dollar one. Thanks for the tips. A pic to show why it is a bit dificult, it would be pretty tough to get a bullet to skid in that bore:

61200

[texassako]

I quess when in doubt, pull out the book. Remington did make these cartridges with smaller bores in mind than one would expect today, designed to be .312"/.319" 7 groove with 1:14 twist. .30 Rem was supposed to be .300/.307 7 groove with 1:12 twist, .25 Rem was .250/.257 6 groove with 1:10 twist, and .35 Rem was .349/.356 7 groove with 1:16 twist.

[Char-Gar]

If you are going to continue with cast bullets you need to find something better than a set of calipers to do your measuring. Even the best set is not as good as a low end micrometer. I have a set of $150 Starett calipers and I do not trust them for the work you are undertaking. Invest in a good micrometer and a set of pin gages or expanding hole gages. You will be like a dog chasing his tail until you do. Precision mesuring instruments cost money, but will last a lifetime if not abused. Sitting in the original box on this desk if a Starett T436FL one inch micrometer than measures .0001. I bought is new in 1968 and it still looks and works like it was new. I bought a set of Starett expanding hole gages the same year and they too are still as good as new.

To your concern at hand: Way to much is made over the "slug the bore" mantra. The critical dimension is the throat/free bore as long as it is larger than the groove diameter which is almost always the case. If you can seat a round (with a cast bullet) without shaving lead in the throat you are good to go. The largest diameter you can use like this, will most often be the most accurate. Measuring the inside of a fired case can be very helpful, but you are getting the size of the chamber neck minus the thickness of the brass. That measurment is not 100% indicative how what the diameter of the throat will be. That measurment will tell you how big a cast bullet you can chamber in your rifle without binding in the chamber neck. You do need the outside diamter of the neck of the loaded round to fit with ease into the chamber and allow a little room from the case to exand on firing and turn loose of the bullet. It doesn't take much .001 should do the trick.

[runfiverun]

charles is correct in the measuring.
what i gave was a quick dirty way to determine what will fit.
the shape you have there looks like it would work pretty well with some lube grooves and a gas check.
you'll want the nose smaller of course so those lands aren't cut but will just make light marks.

making a impact of the throat area would give you better dimensions and what should be how long and taper angles and such.
but i'm sure you just want to get something that shoots.
and some easy measurements should give you an idea of what will do the job.

the neck filled with groove filler plus a little.
a crimp groove.
a drive band to fill some throat.
a stout nose that scuffs the lands.
that should be all you need for good accuracy at nominal cast velocity's

[texassako]

If you are going to continue with cast bullets you need to find something better than a set of calipers to do your measuring. Even the best set is not as good as a low end micrometer. I have a set of $150 Starett calipers and I do not trust them for the work you are undertaking. Invest in a good micrometer and a set of pin gages or expanding hole gages. You will be like a dog chasing his tail until you do. Precision mesuring instruments cost money, but will last a lifetime if not abused. Sitting in the original box on this desk if a Starett T436FL one inch micrometer than measures .0001. I bought is new in 1968 and it still looks and works like it was new. I bought a set of Starett expanding hole gages the same year and they too are still as good as new.

To your concern at hand: Way to much is made over the "slug the bore" mantra. The critical dimension is the throat/free bore as long as it is larger than the groove diameter which is almost always the case. If you can seat a round (with a cast bullet) without shaving lead in the throat you are good to go. The largest diameter you can use like this, will most often be the most accurate. Measuring the inside of a fired case can be very helpful, but you are getting the size of the chamber neck minus the thickness of the brass. That measurment is not 100% indicative how what the diameter of the throat will be. That measurment will tell you how big a cast bullet you can chamber in your rifle without binding in the chamber neck. You do need the outside diamter of the neck of the loaded round to fit with ease into the chamber and allow a little room from the case to exand on firing and turn loose of the bullet. It doesn't take much .001 should do the trick.

I have a couple pounds of cerrosafe since I have a habit of buying odd and obscure calibers. Would the best procedure be to cast the chamber and use a good micrometer to get the measurements, or use the gauges? The Model 8 is a long recoil semiauto, would the same tight fit work? It currently functons fine with neck sizing only for jacketed reloads. I know I need better measuring tools and I still have lots to learn; so please bear with me.