Anybody use a V-Angle micrometer for slugging a barrel?

[Down South]

I was thinking about buying one of these so that I could slug my S&W barrels. Does anyone have any experience with one. It looks like it would work for the odd number of lands and grooves in the Smiths.

http://i158.photobucket.com/albums/t95/iamdudley_2007/Guns/3389.jpg

[Hip's Ax]

My Arisaka's and Schmidt Rubin rifles have a odd number of lands and grooves. On The SR there are 3 lands and grooves and Parashooter from the SR website told me how to use a slug, a micrometer (a normal one) and gage pins to work out the groove diameter. I was worried about the accuracy of the method so I sprung for a v anvil mic off of EPay and got the exact same results.

Yes , they work well for odd numbers of lands/grooves.

[WILCO]

I've used one for measuring tooling. Very handy to have.

[miestro_jerry]

+1 for the tool, I agree with WILCO


Jerry

[9.3X62AL]

I use a V-block that 45 Nut provided with a conventional micrometer, and am very happy with the results obtained.

[Down South]

I use a V-block that 45 Nut provided with a conventional micrometer, and am very happy with the results obtained.

Now that you mention that, I remember reading something about it a while back. Dang, I ordered the micrometer today.

[Nueces]

Howdy, all. Been off the site for a month, so have just seen this thread (and several hundred others, too).

Years ago, I made a small v-block with an included angle of 108 degrees for measurement of 5-land barrel slugs. Saw a blurb in an old Gun Digest or Handloaders Digest. Worked pretty well, but fiddly to hold all together when miking with a standard mike.

V-angle mikes make this sort of thing easier, but it's not true, as is often said, that any v-anvil mike is good for measuring any odd flute tool or slug. A 60 degree v-anvil, or 3-flute model, will measure 5 flutes, or a S&W barrel slug, only if the lands of the tool or slug are wide enough to lay tangent to the sides of the vee during measurement. This does not happen with the narrow lands of an end mill and is unlikely with a barrel slug. Draw it out on paper, or computer, to see what I mean.

The proper mike for 5-groove barrels is the 5 land model, with the wider 108 degree vee. Less often seen, but I got a good price on a new Starrett on ebay. Mitutoyo also makes a fine one. Once you've seen 'em both, it's easy to pick out the wider vee by sight.

Down South, you'll likely want to exchange that 3-flute model for a 5-flute for your purposes. Hope you can do that. (I'm assuming the photo accompanying your first post is the one you ordered.)

Mark

[jhalcott]

When I was working in the steel mill I had access to any tool in the machine shop. One of the tool makers asked what I wanted to measure with the Angle mic. BULLETS! He said bring them in as there are DIFFERENT mics for different numbers of flutes. I had several .30 cal guns I was loading for and there WAS a small difference with odd numbers of grooves.

[Down South]

Well, that's about my luck. Do all of the research and still get the wrong piece of equipment. I actually ordered the mic for work. Thought it might come in handy to measure round things around here plus I could borrow it from time to time. I've just got the mic in a couple days ago and haven't used it yet. I wonder how much difference the measurements would be compared to the five flute mic? It would be a pain in the butt to exchange since I third party all of my requisitions.

[Pepe Ray]

The problem is found in the width of the grooves and/or the speed of the twist.
If the face surface of the mic will bear on the face surface of the slug, your home free. Otherwise there will be a rocking movement and the mic face will straddle the edges of the grooves, placing the mic face closer to the anvil than you want.
Oh!! It would be sooo much easier to show graphically. Sorry. AND, yes the proper angle for a 5 groove is 108*. S
See 45Nut for a solution.
Pepe Ray

[Cap'n Morgan]

It's not a perfect solution, but:

One way to measure uneven rifled boolits is to make a "saddle" which fit over the stationary anvil on the micrometer. The saddle should have the profile of a semi-circle with a diameter about 0.001 larger than the largest bullet you want to measure, and a "depth" about a third of the bullet diameter. (imagine a 1" ring 3/8" thick and with a .30 hole in the middle) For the best result the hole should be bored on a lathe. The ring is then cut in half and a blind hole is drilled for the micrometer anvil. If you are real nimble fingered you can do without the anvil hole, and just place the bullet in the saddle and measure across both.

The caliber should be "calibrated" against a jacketet bullet of known diameter before measuring.

You would need a saddel for each caliber, although some overlap is acceptable. The error when measuring a five land/groove imprinted .308 bullet (groove width = land width = .10) in a .312 saddle is only .0001" ...and that's in the worst case scenario measuring over a groove. For a three groove rifling the error would still be only .0003".

English isn't my native tongue. Did I make any sense in this post at all? :confused:

[Down South]

English isn't my native tongue. Did I make any sense in this post at all?
You made perfect sense. That's a dang good idea.

[Pepe Ray]

I give up.

[Cap'n Morgan]

I give up.


I knew I should've added a picture. :-D

http://img387.imageshack.us/img387/1134/saddleqo8.jpg (http://imageshack.us)

[Pepe Ray]

And you need a guage for each caliber, right?

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