Powder position sensitivity?

DW357

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So I've been doing a lot of testing with various powders to get my Coonan 357 mag 1911 to cycle with the 10lb spring (intended for 38 special +p). This has forced me to finally bust out the new chronograph I got back in November to see how these loads are running.

I'm using Xtreme plated 158 gr FP bullets (with cannelure) and I started out using 6 gr of 231 at 1.575" using standard primers (CCI) and magnum primers (CCI). I also used a light crimp (half turn of the Lee FCD after touching the casemouth) I was reading on other forums that some powders (231 being one of them) can be position sensitive in long straight wall cartridges with lots of empty space inside. I also read that using magnum primers might help. So I did a quick comparison using 6 gr of 231 with standard and magnum primers. I made 21 rounds of each (3 mags) so I could shoot off one mag at a target to see how they group and then shoot the remaining 2 mags through the chrono to see what they're running at.

Magnum:
893
949
920
845 - tipped gun forward to move powder away from primer
938
1003
971
1010 - tipped gun backwards to move powder close to primer.
927
934
968
930
931
958

AVG 941
ES 165
42


Standard primers:
949
943
966
978
963
935
845 tipped gun forward to move powder away from primer.
914
918
894
895
904
1038 tipped gun back to get powder close to primer.
848

AVG 927
ES 193
SD 51


So there was definitely a slight increase in velocity using the magnum primers but not by much. Both loads grouped well but I'd say the magnum primer loads had just slightly better groups. It's also apparent that 231 is effected by the position of powder which makes sense with the amount of empty space. I'm assuming that the position sensitivity is most likely the cause for the extreme spread? So this is expected when using 231 in large case volumes?

I read that titegroup and bullseye aren't as position sensitive so I just whipped up 21 rounds each using bullseye and TG which I plan to shoot tomorrow after work.

5.2 gr TG same COL, standard primer
6 gr bullseye same COL, standard primer
158 gr Xtreme plated FP bullet. Light crimp

I'd like to mention that I've worked up loads with both TG and Bullseye starting at 4 gr and checked for pressure signs etc.

I'll post the results tomorrow.
 
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Sorry for the weird font size. Cutting and pasting from the notepad app on my iPhone doesn't work great I've realized.
 
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Alliant's 2400 is not supposed to be as position sensitive. You might find that works well in .357 Magnum and .38 Special +P. No load data for .38 Special, but that shouldn't matter in your Coonan. Perhaps the hard copy Alliant manuals give more ranges of powder charges in specific calibers.
http://www.alliantpowder.com/reloaders/powderlist.aspx?type=1&powderid=9&cartridge=28

2400 is great. I got about 8 pounds of that but I save it for my real hot magnum loads. I'm just trying to make some lighter loads for the lighter spring that Coonan supplied with the gun. Once in a while I'd like to shoot some softer shooting loads so it's easier on the hand and wallet lol. Also if my friends want to shoot it but aren't comfortable with the recoil yet.
 
Unique is notorious for being NOT position sensitive. My fav 357 load is 5.2gr under a 158gr cast bullet. Very economical, pleasant target load.

Yeah I think I read on another forum that Unique isn't position sensitive. Probably because it fills the case better than 231 and other faster burning powders. I do have a few pounds of Power Pistol that I could try - that's just as slow if not slower burning than Unique.
 
I realize that it would make more sense to better prove any position sensitivity by shooting more than just one round after the gun was tipped forward/backward. I think I was so eager to shoot these rounds and run them through the chrono that I didn't think to shoot more than one round tipped forward/backward.

I made 3 mags worth (21 rounds) each with Bullseye and TG so I could shoot one mag after the gun was tipped forward, then shoot another mag with the gun tipped back. Then shoot the last mag normally through the chrono.
 
As far as position sensitivity goes, FWIW I load 13.5gr unique under a 405gr cast bullet for 45/70 and it chronos very consistent. That's a huge case to fill comparatively.
 
As far as position sensitivity goes, FWIW I load 13.5gr unique under a 405gr cast bullet for 45/70 and it chronos very consistent. That's a huge case to fill comparatively.

Wow, ya that is a lot of case to fill for sure. Good to know. Thanks.
 
Okay so here are the results using Titegroup and Bullseye. I did a 5 shot group for each powder just to check accuracy. Then I shot 8 rounds of each powder but after the gun was tipped forward and backward. I somehow missed or the chrono didn't pick up one of my shots when shooting the rounds after tipped forward and after tipped backward. So that's why there's only 7 rounds shot in the TG Backward string and 7 shots in the BE Forward string.

One thing to note is that I shook the gun pointed at the ground and at the sky to really ensure the powder was being moved toward/away from the primer. Also both of these loads shot VERY tight groups at 10 yards so accuracy wasn't an issue.

TG Foward
842
889
843
866
831
797
864
870

AVG 850
ES 92
SD 28


TG Backward
992
957
994
985
968
976
993

AVG 980
ES 37
SD 14

BE Forward
916
935
951
963
954
971
980

AVG 952
ES 64
SD 21

BE Backward
1079
1048
1094
1097
1107
1095
1077
1106
AVG 1087
ES 59
SD 19
 
The SD for each of the powders were somewhat close to each other. I would probably have to do the same test (8 shot string forward and backward then 5 shot group to check accuracy) but using 231 to really say that 231 is position sensitive. But at the same time, if they're shooting accurately and clean why should I care? Just use the powders I have available on hand and be done. It's still fun to test these things though. Not sure if it's useful info for anyone [laugh]
 
There certainly is a difference in velocity between "powder forward" and "powder backward". It's interesting that accuracy was about the same and the SD in the BE loads appear to basically be the same. The Titegroup SD has a larger difference but not enough to worry about.

Sure makes me think the final results (accuracy) using these two powders is NOT position sensitive.
 
Sure makes me think the final results (accuracy) using these two powders is NOT position sensitive.

It's handgun ammo. In most cases, you will not detect any ammo-induced inaccuracy.

For example, let's say you loaded some horribly inaccurate ammo - somewhere in the neighborhood of 5 MOA accuracy capability. At 50 feet, 5 MOA is about 3/4".
 
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It's handgun ammo. In most cases, you will not detect any ammo-induced inaccuracy.

For example, let's say you loaded some horribly inaccurate ammo - somewhere in the neighborhood of 5 MOA accuracy capability. At 50 feet, 5 MOA is about 3/4".

Very good point!
 
This data is a revelation to me. Wow.

I've never considered tipped back vs forward and how it affected MV. I understood conceptually that it would make a difference, but never thought it would be so consistently repeatable and also that the difference would be so HUGE.

In both cases it was about 130 fps.


Re elevation adjustment with MV, like Eddie said, it won't make much of a difference.

Last year, when I was getting ready for a long range rifle class at Sig, I ran some external ballistic numbers on the 175 SMK that I was shooting. A 30 FPS difference at 100 yards yielded only a tenth of an inch or so variance.

Because the bullet is accelerating downwards and not moving at a constant rate, the difference changes as a square function of distance.

So at 1000 yards, a 30 fps difference (centered around 2720 fps with a 175 SMK) yielded a vertical shift of 18 inches!!!

Don
 
This data is a revelation to me. Wow.

I've never considered tipped back vs forward and how it affected MV. I understood conceptually that it would make a difference, but never thought it would be so consistently repeatable and also that the difference would be so HUGE.

In both cases it was about 130 fps.


Re elevation adjustment with MV, like Eddie said, it won't make much of a difference.

Last year, when I was getting ready for a long range rifle class at Sig, I ran some external ballistic numbers on the 175 SMK that I was shooting. A 30 FPS difference at 100 yards yielded only a tenth of an inch or so variance.

Because the bullet is accelerating downwards and not moving at a constant rate, the difference changes as a square function of distance.

So at 1000 yards, a 30 fps difference (centered around 2720 fps with a 175 SMK) yielded a vertical shift of 18 inches!!!

Don

Ya I was quite surprised myself with the results. I didn't think I was going to see a 130 fps difference.

I was sharing this data with some reloaders on the 1911 forums and one of the guys who shoots in IDPA/USPSA, said that when they do the chrono testing for power factor etc that they make/allow people to tip their gun back to get the most velocity they can? I don't know crap about IDPA/USPSA but I thought that was interesting that they do that.

An 18" shift is crazy but then again that's over a half mile away lol. Nice.
 
2400 can be very position sensitive in large case's like 44 mag - 45-70 care must be taken to never go below the minimum starting loads . Its possible to get SEE secondary explosive effect which can be far more dangerous than going over the max. Ive personally seen a ruger black 44 with half the cylinder and top strap completely blown off the gun , when the remaing reloads were pulled down they were found to be loaded with 12.5 grs. of 2400 and not 22.5 grs.
 
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Going way back when they started loading black powder high volume cases with dual base smokeless powders they used buffers like dacron (angel hair) or corn starch to replace the volume in the case and keep the powder next to the primer . Because in its orginal loading of 70grs of black powder filled the case pretty well. The problem with 2400 it doesnt like room to grow the pressure spike are incredibly high in light loaded high volume cases. SEE happens when the majority of the powder in a large case ends up at the neck of the case the powder in the case can detonate and not burn as it should . As far as light loads for 45-70 I use 13grs of red dot . The minium load I use with 2400 is 20 rs.
 
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2400 can be very position sensitive in large case's like 44 mag - 45-70 care must be taken to never go below the minimum starting loads . Its possible to get SEC , secondary explosive effect which can be far more dangerous than going over the max. Ive personally seen a ruger black 44 with half the cylinder and top strap completely blown off the gun , when the remaing reloads were pulled down they were found to be loaded with 12.5 grs. of 2400 and not 22.5 grs.

Yikes. I load them at 14.7 gr which is 0.3 gr below max. I weigh every 10th charged case so hopefully I'll never experience SEC. Thanks for the info.
 
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