.0001 under sized neck thickness ?

M

matchman

Guest
I had maby 6 out of 100 for what ever the reason that mic this slight amount under size. Chuck them in with the with the rest or segregate ?
Can .0001 influence group accuracy ?
Thanks
Adam
 
matchman

have you got the zero's right if so its cool to go with them unless you can shoot a .0xxx agg.jim
 
"One ten thousandth"

Adam: I'm sure there are those who will disagree, but, measurements of one ten thousandths ( or even 2,3,&4) are of little concern to me. I can vary the measurement that much when using a Starrett dial indicator or a Mitutoyo ball micrometer just by how much pressure I put on the adjusting wheel of the dial indicator or the adjustment of the ball mic. My limits are one half of a thousandth, .0005", and even then is "rounded" up or down to the nearest three decimal. Just do not understand how it's possible to measure to that degree of accuracy ( and consistancy) with the hand tools we use. Seems like those measurements are more suited to a labratory enviornment.
 
Last edited by a moderator:
sorry shuster,,,but the ability to measure to 0.0001 is common with std machinist hand tools.

not every project or part is spec'd to 0.0000. some are only 0.00, common is 0.000, and to have some or all of a spec to be 0.0000 is not uncommon.

now if that is what the gentleman meant is another story.....


mike in co
 
matchman said:
Can .0001 influence group accuracy? Thanks Adam
Click to expand...

I would venture to say that the WIND, GUN HANDLING, and POWDER TUNING has much more of an influence! ;)
 
Last edited by a moderator:
This brings to mind the old saying "You measure it with micrometer but mark it with a grease pencil and cut it with an axe" :confused:
 
.0001 at the kitchen table with a tool that look's like my old grade school pencil sharpener. You should be able to get closer than that.
 
I knew I would get some entertaining answers ! Pencil sharpener ...still chuckling... I was almost afraid to ask !
Yes I was asking a tenth of a thousandth .
I was surprised no one equated anything to the tides or ?????
Thanks I get the drift.
Adam
 
A few years back I shot with a guy who was not only a very good shot, but a topnotch machinist in the aerospace industry. When people started talking about measuring "tenths" he'd just grin. He commented once that when something had to be measured to 0.0001" it was done in a climate controlled room amongst other things.

If the temperature varies much at all with most metals it can cause enough expansion or contraction to mess things up, not to mention being held in someone's hot, sweaty paws.

I do good with yardsticks though. :D
 
Boyd Allen said:
No
Click to expand...

:D



Add one here......


AND, add one (( :D )) for all the real machinists who KNOW that calling out tenths with hand tools is pure BS. Tenths are fictional, they're right there with "if I do my part the gun will shoot XXXX.XX all day long" .......

yup, and if I had an egg I could have green eggs and ham,

if I had some ham

LOL

Now.... regarding segregation...... It is my opinion that segregating by seating feel on the arbor press can be meaningful. AFTER 3 or 4 firings. You may also find a couple things, #1, those thick and thin necks have magickly juxtaposed themselves about and #2 a neck that measures "thin" may well be one of the stiff-seating ones! ;)

al
 
mike in co;
You are absolutely correct if those tools include a temperature and climate controlled room,a certified set of gage blocks,a certified surface plate(lab grade),a .00005 electronic indicator and a qualified operator. Any thing less is pure and simple guess work. The accurate measurement of .0001 is not so much a measurement as it is a comparision to a known standard;keyword is accurate.

Mike Swartz
 
Measuring

What Mike Swartz said.

Ascertaining an exact size to .0001 is difficuly outside a controled invoroment. But, if you give me two objects, say bullets, and a proper set of Micrometers, I can tell you the difference in the two, possibly within .0001. Well, sometimes "possibly". Any good machinist will tell you that you have to be very realistic about capabilities when dealing with extremely small variations..........jackie
 
and

now we wonder about dialing a barrel in to the .0001?:confused:When I tried it I settled on the best I could get it less than !/2 a thou.Does it shoot?We'll see.
 
Mckinnie

It's two different things. When measuring, there is always the skill of the Craftsmen to be considered.

When indicating, you are dependent upon the mechanicle integrity of the tools, ie, the indicator, and the lathes spindle bearing capabilities. On some cheaper lathes, (or high end machines that have seen better days), the bearings will not run much better than .0003 to .0005, sort of difficult to dial in something within .0001 under those circumstances.

I indictate barrels in to within .0001 on a regular basis. But even that can be a compromise. For instance, if one land habitually reads a couple of tenths higher, you can split the difference between it and one opposite. When dealing with items that are not perfectly straight, or even round for that matter, you have to decide where the compromise will be.

Even all of this becomes a moot point when dealing with some of the anomalies that you encounter in the ID of a barrel. For instance, you can indicate a specific spot as close as your capabilities allow, and move the indiactor stylus 1/4 inch, forward or back. and you suddenly get .0003 difference.

That is why it irks me to have a barrel that has one of those "spots" right up there where the throat is going to be. Every barrel has them, it is the nature of the beast, but I always prefer them to be somewhere else.......jackie
 
You must log in or register to reply here.
Back
Top