No 4 Mk1*

[twotoescharlie]

I have a longbranch, 5 groove rifleing. I have slugged it but am kinda stumped as how to measure it. Can any of you old fellers(young 'uns too) tell me the process for measuring a slug with odd lands and grooves? got a micrometer and a dial caliper, but I ain't got no slide rule. Thanks

TTC

[Bob S]

The simplest way I know, without a special micrometer, or a set of special V-blocks and dial indicator, is to wrap the slug tightly with a fairly thin shim stock of brass or steel, and carfully mike the resulting "patched" bullet. Then subtract twice the thickness of the shim stock that you used. I generally use .003 or .005 steel that is available from Brownell's. Anything thinner than that is too flimsy to get an accurate reading with the mike over the groove; anything much thicker than that does not wrap tight enough. You need to use a light touch on the mike.

Resp'y,
Bob S.

[trooperdan]

Bob, now that is a neat, simply trick that I've never thought of! Thanks a bunch!

[twotoescharlie]

I have several old feeler guages going downto .001 , will try this tomorrow.


TTC

[Buckshot]

.................Here's a second way, and it requires a caliper (dial or vernier). As close to the muzzle as possible, and using the knife edge of the jaws measure the barrel OD. Now measure the groove to the outside bbl OD. Take this last figure, double it and subtract it from the barrel original barrel OD figure.

You can do the same for the lands to get a bore diameter. Check the groove to outside measurements at each groove to assure yourself the bore is coincident with the barrel OD.

...............Buckshot

[Bad Ass Wallace]

My method is similar; wrap in shim brass, nick the overlap with a scalple and measure the length and divide by 3.142 = diameter.

[Ricochet]

I've been badly fooled by measuring old milsurps' bores at the muzzle. Belled by cleaning rod wear.

[cropcirclewalker]

I say this alot.

One can cut like a one inch strip of aluminum out of a beer can with a pair of scissors. :drinks:

Shim stock?

We don't need no steenkin' shim stock.

I guess a soda can would work as well but where to find a soda can? Might as well go buy some shim stock. [smilie=1:

Mike a regular boolit. One that is all round and which you know the size. Like as it you just shoved it through a .309 sizer.

Mike it. Record measurement. Likely to be .309.

Wrap the beer can stock around it.

Mike it again. record measurement.

Subtract previously recorded measurment from known boolit measurement, probably .309

That gives you the cumulative amount to subtract from the same piece of beer can which you wrap around the slug.

Make sure that the aluminum strip is long enough to "bridge" enough of the rifling and yet maintain its curvature.

Get it?

Got it?

Good.

[twotoescharlie]

thanks to everyone.


TTC

[curator]

There is a retired professional engineer who offers his expert measuring service free of charge. His name is O.H. McKagen, 9229 Arlington Blvd. Apt 551, Fairfax, VA 22031. He has v-block mictometers and other specialized measuring tools. Make a good slug, wrap it carefully and mail it to him with a stamped self-addressed envelope for his reply. He can even measure Maritini henry, and 3-groove Springfield slugs. He's an interesting fellow, and an occasional contributer to the Cast Bullet Association's journal.