Hogdon sr4756 data no good !!

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Hogdon sr4756 data no good !!

Postby Sagebrush » Fri Nov 25, 2011 11:01 am

Hodgdon data with the 7.7" barrel for revolvers in .38 special might be off a little.
I took my new S&W snub nose 1 1/7" out the other day to test some 148wc target loads and light 110 jhp loads.

Their STARTING LOAD data called for 5.5 grains of SR 4756 913 fps at 12,300 psi.

I set my chrony up at 8 feet and shot just 4 rounds, the average was ................... 467 fps

Sure glad I did not shoot this load in my 6" barrel !!

loads came out as 471.3, 474.6, 457.1 & 452.3.
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Re: Hogdon sr4756 data no good !!

Postby apexhunter » Tue Nov 29, 2011 2:44 pm

Not having the numbers to extrapolate velocity loss in the shorter barrel it could be that the snubby simply doesn't provide enough length to develop more than the 467'/sec with that particular load as you basically got a 7.7% per inch loss in velocity. It would be interesting to see what you get from the 6" bbl in comparison...if it came in around 780'/sec you would be following the
"curve" for that load pretty well. At least your numbers were pretty damned consistent.
"Shoot low boys...they're riding shetland ponies in search of true grit" Lewis Grizzard
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Re: Hogdon sr4756 data no good !!

Postby Sagebrush » Wed Nov 30, 2011 11:55 am

Here is what I got from SR 4756 out of my 6" 686 S&W MAGNUM revolver............
DO NOT use these loads, they are not published data,just my test that do not have pressure readings !!
As you can see this powder has a mind of its own.

Hornady 110 XTP with medium crimp all with Federal 100 primers.

6.2 grs 817 - 961 fps ES 144fps
6.6 grs 875 - 1135 es 260
7.5 grs 970 - 1056 es 86
8.0 grs 1179 - 1471 es 291

This last load is definately a "No,No" in a 38 special.

After testing a snubby S&W I found out that SR 4756 is too slow to work in these short barrels and is
only at its best in 6" barrels and maximum loads in steel frames or K frame guns or more, due to the
velosity jumps. Back to the drawing boards..............

Found out on the net that this powder is also "Position sensitive" and that a 60% case volume with a bullet loaded,will
help stabilise its FPS.............as you can see, my figures ,prove this out. I also used wspm, cci500 & 550 primers
with this powder, but thats another, story.
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