Measuring the taper crimp

Has anyone else noticed how stinkin hard it is to measure your taper crimp on your .45? I get out the loop and light and use my calibrated eyeball to just barely measure the very tip of the case and then I get a different but close reading every time with the calipers. I have given this some thought and taken a lot of measurements and I have developed a method of measuring my crimp that my old eyes can do and get repeatable results.
  To make a long story not quite as long I measure the length of the crimp on the case mouth. The crimp is very visible and easy to measure. Repeated measurements of my "Dillon" taper die shows a 10:1 length vs crimp. A crimp line .040" long gives me a crimp of .004". If I have a .472 case and a .040 visible crimp then I get a crimp of .468.
  I have only done this with Dillon dies. Hopefully someone will try this method with other brands and post some feedback.

Len

I just look at them at 50x on the optical comparator....

I lock my caliper to a setting such as 0.470 and then see if the case mouth makes it between or not.  Then I adjust my caliper in or out and lock it again, or adjust my die in or out if that's what I'm looking for.

I know there are a lot of ways to get the measurement. A go-no go gauge like Ed suggests or a 50x optical comparator (Walmart isle 7). But I was trying to come up with something anyone can do easy with the tools on every re-loading bench. It would be just as easy to say (with Dillon) to crimp the case till it shows a .040" mark as to say " crimp to .468" and one of those statements is a lot easier to measure and yields the same results. I know that is re-inventing the wheel but it might make it easier for some.

Len

You can get a caliper with a locking screw at Harbor Freight Tools for $12 to do the operation that Ed Hall described.

....you might be able to find enough coupons on the internet to get it for less.

I find the often stated .470 crimp to be straight wall.  I.E. no taper. 

My crimps are at least .004 less than straight wall (diameter)

With a trained eye, holding the round side and a straight edge on caliper together against a light you can see the taper when it is there.  And I do not hesitate to crimp deep like .465 ala Giles.

Oh! And I have 3 calipers.  The cheep digital never agrees with the better Starrett or Mauser set even when each is set tp a 1" standard and zero checked.  Someday I should compare them all to my mike.  At this time I am satisfied with the visual against the light with an initial setting to be .004 (or more) under straight wall

In a similar action to Jack, I often place two cartridges side by side to evaluate the crimps.

Jack H wrote:I find the often stated .470 crimp to be straight wall.  I.E. no taper. 

My crimps are at least .004 less than straight wall (diameter)

With a trained eye, holding the round side and a straight edge on caliper together against a light you can see the taper when it is there.  And I do not hesitate to crimp deep like .465 ala Giles.

Oh! And I have 3 calipers.  The cheep digital never agrees with the better Starrett or Mauser set even when each is set tp a 1" standard and zero checked.  Someday I should compare them all to my mike.  At this time I am satisfied with the visual against the light with an initial setting to be .004 (or more) under straight wall

I have taken custody of my father's bullseye equipment and I was fascinated to find a paper with instructions, for Star produced equipment, that indicated (as you state) that a crimp of .465" was recommended. My accurized pistols never performed well (tested with a Ransom Rest) with a crimp tighter than Ed Hall's .470", but I've never used Star reloading equipment.

Looks like I will be testing my .469 crimp tomorrow. The latest batch of ACME cast bullets that I opened to load yesterday seem to mic right at .452, they don't feel all that 'secure' although I only had one round that I could pull back out with my fingers after crimping. I always thought that cast ought to be a few thousandths larger than bore diameter ...... Probably just 'seat of the pants' testing but we'll see how it goes. I may be turning that crimp die down a bunch more tomorrow night!

Bruce

Fire Escape

I posted this idea to see if it would help anyone figure how much crimp they are getting. When/if you turn that crimp die  down take a look at the case. When I have the right (about .004") crimp then I have .040" of taper showing on the case. It is really easy to see. Like Jack looks for, you should see a definite crimp when comparing to a straight case.
Len

Walmart, aisle 7?

https://m.mscdirect.com/mobileweb/product_detail?id=89305940&hasRestrictedParts=false. Not quite Walmart but close.

james r chapman wrote:Walmart, aisle 7?

  I guess my point was that it was not a common item. That was my feeble attempt at humor.

Len

I should probably mention that my 0.470" crimp is pertaining to the Nosler and Zero 185gr JHP bullets.  I do not believe in over crimping these bullets.  But, then again, the best anyone got from my loads out of a barrel tester and my barrel, was 0.989" CTC at 50 yards...

Bullseye season must be winding down in the cold parts of the country. Y'all are welcome to come shoot with us in sunny California.

(Bring water - please!)

OldMaster65 wrote:

james r chapman wrote:Walmart, aisle 7?

  I guess my point was that it was not a common item. That was my feeble attempt at humor.

Len

I  thought it humorous and was just carrying it on...

Jim

This was easy to make & use.
Wes

I knew someone would wipe out the boring bar.


very nicely done

Now that is a worthy project.