44 SPL pressure test of 2400 and 44-250-K

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
---------------------------------------------------------------------------------------
16.0………WRA………2 ½ …………1225……..21…….69………20,800…….1,400….4,200
……………….SL………..WLP…………1288……..19…….64………23,400…….1, 300….4,000

16.5……… WRA………2 ½ …………1275……..11…….29………22,500……..700……2,000
……………….SL………..WLP……….…1325………9………32………25,000……..90 0……2,900

17.0……… WRA………2 ½ …………1346……..13…….43………26,400…….1,300….3,900
……………….SL………..WLP……….…1367………8………25………26,300………700 …...1,800

17.5……….WRA………2 ½ …………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;
---------- ------------------------------------------------------------------------------

16.0…….. WRA………2 ½ …………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 ½” barreled Colt FT SAs. So I chronographed (10 shots) of 17.5 gr in the WRA cases with 2 ½ 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……..

Oh. I thought that read “.44 SPL pleasure test...” at first.


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Thanks, Larry Gibson, more valuable data on some well known loads. Since my 44 specials are both 5 shot midsize guns(GP100 and 696), you have confirmed these loads are more than I want to put thru them. And, even better, a quantifiable value to make the decision. I suspect the 17 gr loads might have been quite a bit of “pleasure”! Would be a handful in a 696 for sure!

Very interesting. I have had good results in the past using 16 grains of #2400 in .44 Magnum brass with good accuracy and acceptable ballistic uniformity.

Attachment 263986

Thanks for the tests Larry. Good information there. Do you think chamber pressure would be different from a revolver?

When I bought my Flat Top Blackhawk some 7 years ago, I tried the Keith load too:

https://i.imgur.com/uSkuOb9l.jpg

I was really surprised at the accuracy and the pictured group wasn't a fluke, as I shot a few others. The bullet in that load was a 429421.

For the game I hunt, I now load the RCBS 44-250 KT and velocities are slightly lower than same loads with the 429421 because of the difference in the amount of bullet in the case. I don't see any need in loading over 1,000 fps unless someday I get an untamed follicle and decide to pursue elk with a revolver instead of a rifle.

Thanks again for your work.

35W

Thank you for post Larry , this information is going to be very helpful for many of us.

Larry , I personally want to thank you for that info / test using different loads and showing only slight difference between Alliant / Hercules powders . It shows only " lot to lot " variation , as you have stated numerous times in the past . Regards Paul

35 Whelen

"Do you think chamber pressure would be different from a revolver?"

It is "assumed", most often, the pressure would be slightly less in a revolver chamber than in a test barrel given the same ammunition. The thought is the long cylinder throat [essentially free-bore] and the barrel cylinder gap would reduce the psi. However, after observing the measured time/pressure curves and the "rise" to peak pressure of many pistol loads indicates peak pressure in handgun cartridges would most often occur before the bullet is fully into the barrel. That is even with the slow burning powders such as 2400. That's why, when pressures are excessive, the bulging and/or bursting occurs in the cylinder.

Many years ago before I began pressure testing I read an article where an Oehler M43 was used to measure the psi of a 357 magnum with the strain gauge affixed over a chamber on a revolver cylinder. As I recall (?) t was found the measured psi was very close to that obtained in a solid test barrel with the same ammunition. I've wanted to do the same test but since the bluing is removed to affix the gauge I haven't done it. Thought maybe a stainless might work as well or a revolver that was going to be refinished? Just haven't found a "donor" revolver for that yet as there must also be sufficient space between the cylinder and top strap for the gauge to freely fit.

Well it is great to see the difference in the Starline cases I don't think I will work up past 16 grains with them in my flat top Ruger .
Thanks again.
For another great post.

I have long opined that since the Flattop 45 is known to be safe with 45ACP+P pressures of 23kpsi, that the Flattop 44 would be safe with loads up to 25kpsi because of it's slightly thicker cylinder walls.

The load with 17.0gr 2400 slightly eclipses that figure, but not by much, (and since my 25k pressure rating was purely speculative, no real testing or proven data to substantiate such claim), I would say that I would consider 17.0gr 2400 a safe but maximum charge in SL brass, with the same boolit at the same COA.

Just out of curiosity I would be interested in the same tests, using H110, the other "go to" slow burn powder. Of course charge weights would be different.

Thank you VERY much Larry for your time and expertise and for posting your results!

Thanx Larry. It seems you managed to prove that some of our basic ideas have some validity. I'm surprised there wasn't more difference in some of the pressures and velocity values. H2400 and A2400 are really close in burning rates and modern cases and primers do seem to cause slightly higher pressures, but not as much as I might have assumed. Speculation is well and good but real data is very welcome. Thanx again for the labor and expense for the test........

Good work!

Thank you!

Three44s

Good data Larry ... if I was even remotely nearby, I'd bring some VvN110 over to see what that should test out to under the 250-K as well. I had my hopes up that someone closer would offer. Nonetheless, Hats off for the 2400 work.

I'd like to see the results on the VV 110 myself.......

I checked the LGS's for a lb of VV 110 but found none. Not surprising given the current situation......:cry:

Thanks, Larry!

Thanks for all the work, Larry. Do you happen to know the case capacity of the WRA cases? I've been looking for some to measure the water capacity in grains for my load notes. Seems they are pretty scarce nowadays.

Do you want some WRA cases?

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