Caliper mystery

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bluetick
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Caliper mystery

Post by bluetick »

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

Post by Ranch Dog »

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

Post by Macd »

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.
bluetick
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Re: Caliper mystery

Post by bluetick »

.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

Post by mikld »

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.)?
bluetick
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Re: Caliper mystery

Post by bluetick »

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

Post by Ranch Dog »

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

Post by mikld »

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

Post by Macd »

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

Post by mr surveyor »

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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