Caliper mystery

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Caliper mystery

Postby bluetick » 30 Jan 2019 22

I seated twenty 44 spls (at the cannelure) and they all measured 1.450. The minimum COL is 1.495. Then I crimped them and re-measured. Now they’re all measuring about 1.490. What’s going on? Anyhoo, I wonder if .005 under would create unsafe pressure. I’m also wondering if my calipers are off, or I’m forcing the thumbwheel without realizing it. Any thiughts?
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Re: Caliper mystery

Postby Ranch Dog » 31 Jan 2019 07

bluetick wrote:Now they’re all measuring about 1.490.

The way I read it is that they grew longer so that will reduce the pressure.
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Re: Caliper mystery

Postby Macd » 31 Jan 2019 11

If you give bullet weight and make, powder and amount I will run a Quickload check. The growth could just be the case mouth pushing the bullet forward to get into the cannelure (Assuming roll crimp). Pressure change in the .44 calibre with a slight decrease in C.0.L. should be insignificant unless you are compressing a powder like L'l Gun. If you want to check the accuracy of your calipers or your technique use a set of clean flat feeler gauges. To check if it is consistent along its scale you can use some bond paper. Measure a sheet, fold it over and measure again and repeat several times. The measurement should increase in line with the number of folds at least within the error tolerance of your calipers.
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Re: Caliper mystery

Postby bluetick » 31 Jan 2019 14

.44 spl, 200 grain hornady jacketed, and 6.7 grains of Unique to send it back on its way. Minimum COL is 1.495.
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Re: Caliper mystery

Postby mikld » 31 Jan 2019 14

Am I right; you seated bullets, measured OAL, then crimped and remeasured, the OAL grew .040"? Since my first revolver reload (1969), I have just seated to the crimp groove/cannalure and disregarded book OAL. I've reloaded a bunch of 44 Specials but none grew with crimping, some shrunk a few thousandths, but none grew. What set up are you using (press, dies, etc.)?
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Re: Caliper mystery

Postby bluetick » 31 Jan 2019 15

Lee single stage press; lee dies. Separate crimping.
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Re: Caliper mystery

Postby Ranch Dog » 02 Feb 2019 06

Still not clear, so did they increase in length when completed?
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Re: Caliper mystery

Postby mikld » 02 Feb 2019 14

C'mon back bluetick. Nobody's gonna laugh at you for misreading yer calipers. BTDT on many occasions... ;)
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Re: Caliper mystery

Postby Macd » 02 Feb 2019 15

bluetick wrote:.44 spl, 200 grain Hornady jacketed, and 6.7 grains of Unique to send it back on its way. Minimum COL is 1.495.


QL Predictions
I used Hornady XTP as it was the only one I could find for the .44 spl at 200 grains.
Pmax SAAMI = 15,500 PSI

1.490 = 13,206 PSI
1.495 = 13,095 PSI

At 1.450 QL predicts 14,196 PSI or 92% of SAAMI max. My own preference is to keep handgun loads below 90% as it is easier on the gun and usually on my arthritis.

I couldn't find a similar load to the one you describe in any of my manuals nor on the Alliant site. 6.7 grains of Unique is below minimum for a COL of 1.490 in all the references.
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Re: Caliper mystery

Postby mr surveyor » 02 Feb 2019 16

I would ask that bluetick verify his numbers stated in the original post. Something about those numbers just don't seem to click with my brain.

just trying to follow


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