44 SPL with 2400 & 44-250-K; Keith’s loads
In the previous thread [http://castboolits.gunloads.com/show...d-report/page3, post #53] I posted this;
“Yesterday I loaded up the 44 SPL test rounds. I loaded 10 shots each of 16.0, 16.5, 17.0 and 17.5 gr Alliant 2400 in both WRA cases and new Starline 44 SPL cases. The bullet was the RCBS 44-250-K cast of COWW + 2 % tin. They were sized .430 and lubed with BAC. OAL is; 1.565".
Surprisingly the WRA cases were only 0.5. gr less weight than the Starline cases. The WRAs also had a much larger ES of weight than did the Starline cases.
The WRAs were primed with some old Remington 2 1/2 LP primers as those may have been used by Keith. The Starline cases were primed with WLP primers as they are readily available today.
I also loaded 10 shots each of both WRA/2 1/2 cases and Starline/WLP cases and 16.0 gr of 27 year old Hercules 2400 for a comparison to the same loads with Alliant 2400. However, 10 shots of 17.5 gr Alliant 2400 were also loaded in WRA cases with WLP primers for a direct comparison of case to case pressures.”
The test was conducted early this morning. There were no surprises as the pressures and velocities were as expected. Previously in the thread I had posted the psi of a previous test (2/25/2019) conducted last year using the RCBS 44-250-K bullet in Starline 44 SPL cases with Winchester WLP primers using 16.0 gr Hercules 2400. The psi was 19,300 with a velocity of 1198 fps out of the same test Contender barrel. Test temperature then was 45 degrees.
The test this morning was conducted on the same range from the same bench, but the temperature was 85 – 95 degrees during the test. All test equipment and components were shaded however with nothing other than the screens in direct sun light. With that it was expected the 40+ degree difference would give an increase in psi and velocity. It did but not as much as I expected.
Test conditions;
Ten shot test strings of each charge
Target at 50 yards
Start screen at 10’ but the M43 corrects the velocity to the muzzle
Temperature; 85-95 degrees
Humidity; 7%
Barometric pressure; 29.76
Altitude; 908’ ASL
Test firearm;
Contender with 8.4” barrel
Sights; Bushnell 1.5X
Pressure and velocity measured via Oehler M43
Test results WITH Alliant 2400;
A2400……Case……..Primer……Velocity…..SD…..ES……..PSI(M 43)……SD……..ES
Charge
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16.0………WRA………2 ˝ …………1225……..21…….69………20,800…….1,400….4,200
……………….SL………..WLP…………1288……..19…….64………23,400…….1, 300….4,000
16.5……… WRA………2 ˝ …………1275……..11…….29………22,500……..700……2,000
……………….SL………..WLP……….…1325………9………32………25,000……..90 0……2,900
17.0……… WRA………2 ˝ …………1346……..13…….43………26,400…….1,300….3,900
……………….SL………..WLP……….…1367………8………25………26,300………700 …...1,800
17.5……….WRA………2 ˝ …………1378……..14…….41………27,600…….1,800….4,200
……………….SL………..WLP………..…1400……..19…….58………29,800……. 1,500….4,500
Test results with Hercules 2400;
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16.0…….. WRA………2 ˝ …………1275……..19…….54………21,300…….1,200….3,700
……………….SL………..WLP……….…1264……..21…….62………20,600…….1 ,000….3,200
As we can see the Hercules 2400 performed very similar to Alliant 2400.
As to accuracy the 16.0 and 16.5 gr groups all were 2 – 2.5”. Even with the excellent internals recorded accuracy with the 17.0 and 17.5 gr groups ran 4 – 6”. As similar 1350 – 1500 fps velocity loads in magnum cases hold accuracy I’m suspecting the bullets are obturating at the psi level of those charges in the unsupported part of the chamber in front of the 44 SPL cases in the 44 magnum chamber.
I seem to recall(?) Elmer claimed 1200 fps with the 17.5 gr load out of 6 – 6 ˝” barreled Colt FT SAs. So I chronographed (10 shots) of 17.5 gr in the WRA cases with 2 ˝ Remington primers. The muzzle velocity was 1177 fps [20 fps SD, 58 fps ES]. With my old eyes and shaky hands I managed to put 8 of them into 2.9” at 50 yards with the other two making it right at a 4” group……’bout the best I can do with the iron sights. Maybe old Elmer wasn’t too far off……..