Using a recovered cast boolit to measure bore?

[PNW_Steve]

Hey Everyone,

I have been intending to slug barrels on the guns I am going to cast for. I just have not gotten a round tuit yet.

I did recover a cast, powder coated boolit that I fired from my 9mm carbine and did some measuring. I was a bit surprised to find that the "groves" portion measured .3535 compared to the un-fired bullets measuring .3558-.3560

The recovered bullet was intact except for the rifling marks, a few dings a powder residue on the base. The powder coating held up admirably. Very little silver showing on the recovered bullet.

Is this a valid indication of my bore size? Am I spot on size wise with .3559 (avg) in a .3535 bore?

Thanks.

S.

[Winger Ed.]

I wouldn't trust it more than about 95%.
The ballistic labs usually use a deep water tank to fire into for their tests to avoid as much distortion and 'squish' as possible.

A 'low-ish' speed cast boolit is probably accurate enough to measure if it went into something pretty soft.
But in your case, a jacketed bullet would be more true for your measurement since it won't distort on the same impact as easily.

The real deal is to slug the bore.
You get a proper measurement without the violence of stopping a boolit.

[turtlezx]

shoot 1 into your pool or a friends slugging made easy

[gpidaho]

shoot 1 into your pool or a friends slugging made easy

That's how Dick Lee did it!

[PNW_Steve]

shoot 1 into your pool or a friends slugging made easy

That is a great idea! The guy who shot my planer has a pool...... Perhaps a mag dump is in order......

Kidding except for the part about my planer..... Son of a gun showed me his new, empty, 9mm and it was so empty that I now have a .356 hole in one of my cabinets and in my planer. The planer still works but I am concerned as I didn't find an exit hole or the bullet.

Back to the question: In fact I don't know anyone with a pool. They are not very common here. The bullet I recovered is in very good shape. Sitting it next to a new bullet for comparison, the recovered bullet is in quite good shape. I am trying to post a pic but my cell service, from VERIZON, sucks. I will keep trying

[charlie b]

What's wrong with doing a pound cast?

[Winger Ed.]

You might try the official redneck method of bore slugging:

Load a round down as low & slow as ya dare and still have it come out the barrel.
Shoot it into a 5 gallon bucket of water with a big towel on the bottom.

But be safe--- do it over the ground, not in the kitchen.

[PNW_Steve]

What's wrong with doing a pound cast?

AFIK there is nothing wrong with it. I have not tried it.

[PNW_Steve]

Well it doesn't look like I am going to get pictures uploaded. The progress bar goes to 209k then stops. After a bit it errors out.

The recovered bullet is in very good shape. I can see clearly where the rifling was. If I couldn't see that, I would't believe that the bullet had been fired.

[44Blam]

Hey Everyone,

I have been intending to slug barrels on the guns I am going to cast for. I just have not gotten a round tuit yet.

I did recover a cast, powder coated boolit that I fired from my 9mm carbine and did some measuring. I was a bit surprised to find that the "groves" portion measured .3535 compared to the un-fired bullets measuring .3558-.3560

The recovered bullet was intact except for the rifling marks, a few dings a powder residue on the base. The powder coating held up admirably. Very little silver showing on the recovered bullet.

Is this a valid indication of my bore size? Am I spot on size wise with .3559 (avg) in a .3535 bore?

Thanks.

S.

Now you can do it!

[Dusty Bannister]

What some folks might be trying to tell you is that just eyeballing a bullet and saying it is good enough, isn't.

[PNW_Steve]

What some folks might be trying to tell you is that just eyeballing a bullet and saying it is good enough, isn't.

I don't recall ever saying "eyeballing". I think "measuring" was the word I used. It was followed by some numbers. Those came from my micrometer.

[megasupermagnum]

A fired bullet is a kinda-sorta close measurment. By that I mean, probably within .001" or .002". All of my recovered bullets show some deformation, but the good ones are usually decently close to actual groove diameter as determined by slugging and measuring with a micrometer. Based on what I see, you sizing to .356" should be working just fine.

[JonB_in_Glencoe]

SNIP>>>

Is this a valid indication of my bore size?

I don't think so. Besides whatever happened to the boolit after it left the barrel (you don't say), there is spring-back, depending on alloy. Soft lead doesn't spring back.

I like to size all my 9mm boolits to .357 for several different guns that I have, as guns in 9mm can vary, but are rarely larger than .357

[JSnover]

Do a proper bore slug and compare that with your recovered boolit. That'll answer at least two of the questions on this thread.

[robg]

made a mistake ,set my scale for wrong weight had one round stick half out of barrel .should have photoed it .pushed it out and measured it.

[dverna]

I don't think so. Besides whatever happened to the boolit after it left the barrel (you don't say), there is spring-back, depending on alloy. Soft lead doesn't spring back.

I like to size all my 9mm boolits to .357 for several different guns that I have, as guns in 9mm can vary, but are rarely larger than .357

Really sound advice. I have a number of 9mm's and no way I want a different bullet size for each one...what a nightmare that would be. KISS. Feel the same way about my other pistol caliber loads...one size must fit all guns.

[mdi]

I don't think I'd use the dimensions from a fired bullet, especially a higher pressure 9mm. A lot of things happen to a bullet when it is fired; about 35,000 psi smacks it in the butt, it is forced into a tube smaller than it's original diameter, it is spun at over 3,000 revolutions per second, and it hits something at 1,000 feet per second. Slugging a barrel is so much easier (if you are casting your own bullets you have no excuse for not slugging the gun.). I use a method I learned here years ago, cast some lead in a fired case, use an impact puller to remove the slug and you have a tapered, proper diameter slug...