some things my momma never taught me

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  • Last Post 20 February 2019
loophole posted this 18 February 2019

I started casting round balls for my flintlock about 1975, and  bullets for my Ruger 357 handgun soon afterward.  Over the years I have made bullets for a dozen or more rifle and pistol  cartridges.  I have designed bullets and had custom molds made.  I considered most of my cast bullet loads successful and ever had a couple of rifles which regularly gave minute of angle accuracy with my cb loads.  In other words, I thought I knew about cast bullets and handloading.  However, I recently discovered that even after reading books and websites I never learned several important things. 

There must be many cast bullet shooters who, like me, have absolutely no technical or scientific background.  I never even took  a course in mechanical drawing.  Those of you who understand such things often assume non-technical readers can talk your language, but often we only half understand you.  It is possible to make rather accurate loads for modern rifles without knowing much more than the basics, but antique rifles pose other problems.

For example, my experience is that most modern guns have a grove dia set by SAAMI specs and the advice from the Lyman Cast Bullet Handbook to "slug your barrel" isn't usually needed.  Most .30 cal rifles have a groove dia of .308".  Cast bullet shooters found years ago that bullets .001"-.003" over grove dia  usually work well.  When we slug a modern .30 cal  barrel we know what the slug should measure, and we often look at the scale on the mic and see what we expected to see.  Variations in groove dia are within the .001"-.003" acceptable range, so even inaccurate  measurements are within tolerance. 

I recently bought a 1893 Marlin levergun in cal 32-40.  Handloads with .321" dia cast bullets and factory ammo showed keyholes at 50 yds.  I dusted off the dial caliper and measured a slug--.330" I measured.  Before spending money on a custom mold and sizer die I used a micrometer to measure another slug.  .326"  This discrepancy led me to a couple of days trying to learn some of the things machinists and other technically trained people know, but which I'll bet many other handloaders do not. 

I'm not going to teach a course, but I hope this is useful to some of you.

1.  The internet.  Many of you are too old to be really proficient with the net.  I used the computer to check on a few internet gun forums and to order stuff from Midway.  I have discovered that there are dozens of websites and videos a cast bullet shooter may want to see, including all sorts of amiture gunsmithing  instructions.  Just Google a topic or question and there probably is something useful.  Including:

2. Caliper or micrometer.  There are many machinists forums and sites, and a brief query obvipusproduced an explanation of why the mic is usually more accurate and repeatable, as well as instructions on how to use both of them.  Incorrect use is bound to produce inaccurate measurements, and of course, I have been using them wrong for years.

3.  Precision hole dia. Bullet sizer dies are made by Lyman, Lee, and Saeco in common sizes, but what do you do if no one makes one the size you need?  I want one .326" and the obvious way to do this is to get a .325" die from Lyman (about $30 from midway)and enlarge the hole.  A drill bit is not going to work, but if you go to the McMaster-Carr website you will find hundreds of reamers, hones, burrs, and other tools to produce holes that are polished and precise.  Instructions on when and how to use them. I have not done this yet but I have ordered taps, dies, and other machinist tools from them.  Reasonably priced, fast service, and much wider selection than Browells..

4.  NOE Molds.  The owner is a shooter who makes custom molds to your specs.  He also sells a bullet sizing die much like the Lee lube-sizer (about $20) but with interchangeable inserts for a wide range of bullet dia.  I just ordered one for the .326" dia for about $70, but if I want other sizes I can get them for less than $10 each.  Since neither Lee or Lyman makes a .326 sizer die, this looks like a good deal.  Inside neck expanders for the Lee flaring tool for $6.50 each.  

This is too long, and many of you know all of it, but I hope its is useful for others who cannot take a gunsmithing course. If David wants to delete it, that's ok by me.

Steve k   

 

 

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x101airborne posted this 18 February 2019

"Several important things...."

Such as?

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RicinYakima posted this 18 February 2019

Very astute observation, loophole! I am very guilty of writing for people with a technical background. My Dad wanted me to be a tool and die maker and sent me to a pre-apprentice three month course in Cincinnati, OH, at that time the machine tool making center of the world. However, I opted to go to Miami University and studied chemistry. If I ever write anything you want further explanation on, don't hesitate to ask. Ric

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R. Dupraz posted this 18 February 2019

Having lived on this earth for 74 years, one month and seven days, I have learned to trust nothing when it comes to this business of throat, bore and chamber specs, and cast bullets in rifles, modern or not. For starters, I always do a throat slug and then measure that first. The only reason that I would be interested in the bore is to determine if the nose of the intended bore rider bullet will fit into the bore or not. While I do have some measuring tools we are not accurate enough to measure those faint grooves in a lead slug with any degree of accuracy anyway. The nose fit can be dealt with later if need be.

And, I can say that relying on the premise that the SAAMI data will always reflect the chamber and throat specs of any given rifle can lead to making the wrong assumption sometimes.

 

Addendum

I will also add that It isn't always necessary or helpful to size cast bullets .001" or more over throat diameter to get accuracy from a cast bullet in a rifle bore. And that throat sized and undersize cast bullets can shoot well.

I have a 1898 7.62x51 Mauser in which the throat measures .310" and .310" cast shoot best. I also have a custom 6mmx223 barrel where the throat is dead nuts on at .243" And it likes cast bullets sized to .2427" best. Mostly, I think it all depends on what that particular barrel wants. 

 

 

R. 

Hence, the throat slug is king.    

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x101airborne posted this 18 February 2019

I see what the op did by starting a post, then adding to it. I apologize for jumping in before the other paragraphs were added.

 

 

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RicinYakima posted this 18 February 2019

Me too.

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Ken Campbell Iowa posted this 19 February 2019

tips for measuring things ... check the measuring device against a quality mj bullet near your goal before you start on your castings ... that sierra 30 cal brass deer slayer better measure real close to 0.308 every time  before you start on your 311284 castings.  besides, playing with mj keeps us casters humble ... 

yep, calipers especially can betray you pretty quick .. especially the ones your loan to your ( former ) best friend ...

ken

 

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x101airborne posted this 19 February 2019

While we are talking about measuring devices, can anyone recommend a good digital measure stick for the masses?

I have a spin caliper but I am sure I don't know how to use it correctly (and it came from Harbor Freight). 

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2coldhere posted this 19 February 2019

I always thought that a 0-1" mic was zeroed on its own anvil.  I sure wouldn't trust a .308 bullet to set a gage with as I've measured many of them though the years and they aren't all .308.  Has anyone here worked in a gage lab?

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max503 posted this 19 February 2019

Get a gauge block or some other certified standard and practice measuring it with whatever measuring device you use.

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Ken Campbell Iowa posted this 20 February 2019

2coldhere ... sorry, i wasn't clear ...  my thought was that even though a measuring device ... especially calipers ... can indeed zero on their 0 mark ... they can still be off in the range of the piece you are measuring ... thus if a hornady bullet measures 0.3083 when the caliper is new, that same bullet better measure 0.308 2, 3, 4 ... just before you measure your 0.304 or 0.313 casting.

we use a lot of mitutoyo stuff, but dangit the chinese stuff is getting pretty good ... especially if you check it all the time.

funny thing, i gave my son a plastic Lyman caliper to learn on about 1990 ... it is still working just fine today ...

ken

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