Caliper for Slugging a Barrel

[zuke]

I have a 0-1" ball nose Mitutoyo mike I like to use for slugging. Get's right into the groove's.

[ROGER4314]

I'm retired after a lifetime of working around machine shops and manufacturing plants. Granted, if I was running a machine and my job depended on producing good parts, Starrett, B&S and other classics would be my choice. Now, I use Harbor Freight measuring equipment, have also used Enco and a few others. They will all work well until you drop them or allow foreign materials to get into the works. You can kill a B&S caliper as easily as a HF tool by careless handling. That's what I do. Do as you wish.

I do NOT slug barrels! I won't sit and pound on my barrels......sorry. I use Cerrosafe chamber casting alloy. If you want to spend $20 on a 1/2 pound ingot, Midway has it. If you contact Rotometals, they have the same thing currently on sale for $12.99/pound!

Put a paper plug in the barrel and pour the melted Cerrosafe into it. The alloy melts at between 150-190 degrees Fahrenheit. For the first 30 minutes, the alloy shrinks, making it easy to remove. At the one hour mark, the alloy is true to size. Later, it continues to grow until it sets at .0025" oversize.

That's the way I do it. You may do as you wish.

Flash

[georgerkahn]

I agree with ROGER4314 100% -- I have two Cerrosafe ingots I've re-used many, many times -- so unless you lose or perhaps contaminate the stuff (???) -- it lasts! The only thing I wish to add to ROGER4314's post -- as hopefully a very friendly amendment -- is to CLEAN your barrel first, and then clean it again! I once slugged a S&W Victory .38 S&W, finding it to be surprisingly small -- this for a revolver which did in fact go through the (WWII) war! I then cleaned the barrel, jokingly thinking while enough lead and copper was removed to form a boolit for it, and then remeasured. Too many years back for me to recall how many thousandths larger the barrel diameter now was -- but I was impressed enough to never forget that "lesson".
BEST!
geo

[wacki]

For the micrometer folk, do you use the flat piston or pointed anvils?

[EDG]

No matter what quality of caliper you buy it will not have the capability of reading to the nearest .0001.
They simply cannot resolve parts of a thousandth. A vernier micrometer with read to .0001.
A fat thimble micrometer (some Swiss made mikes) will direct read on the thimble to .0005 and the verneir only needs to deal with the other 1/2 thousandth.
Any good micrometer, including those with no vernier, will allow you to estimate to the nearest .0002. You cannot do that with any caliper.

Whether I use my Starrett micrometer or my Mituyomo (sp?) caliper, both of which are checked against a range of test blocks/pins, they both show the same measurement on the same test item. I don't buy the inaccurate caliper argument if you are using quality, calibrated instruments.

[dromia]

I use Mitutoyo calipers and micrometers and am very happy with them. A friend whose business is in the measuring industry checks them no and again for me and they have been spot on from purchase.

[dikman]

I wanted to check the diameter of my revolver chamber, so I poured in some casting resin. Once it was set I knocked it out with a dowel via the nipple hole. I guess you could do a rifle barrel too, just put a piece of fine wire in, attached to a plug or something to seal the barrel and pour in the resin. Once it's set pull the wire to get the plug out - at least, that's the theory.....