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Post by ET on Oct 9, 2019 19:54:05 GMT -5
Have been busy with work but had a nagging question about the Rise time of 4227 compared to 4759 on my last PT test. Found this statement on the internet As a general rule, the faster burning a powder is the faster the pressure climbs inside the case when it's ignited. A slower burning powder creates a slower rising pressure curve. The magic comes from marrying that concept with each cartridge/bullet combo. So my question was 4227 is listed as having a slower burn rate than 4759 but on a PT graph it shows a faster rising pressure curve. So, what gives? Decided to place both powders side by side to see what that might reveal.  I believe I have found my answer, Grain Size. Per given volume of ignited powder more 4227 grains are ignited causing more gas pressure release. Okay now on to my second riddle concerning sabots. Why do sabots not have equal thickness along the length of a petal? We are talking thousands of an inch where the tip of the petal is thinner. I’m starting to wonder if I’m experiencing my second childhood with always asking Why, chuckle. Ed |
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Post by lwh723 on Oct 9, 2019 21:18:26 GMT -5
Probably thinner for mold release
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Post by edge on Oct 10, 2019 8:04:59 GMT -5
4227 and 4759 are single base powders, only nitrocellulose and no nitroglycerin.
Grain per grain, they have the same energy.
The 4759 has a large hole running thru the center of each grain which adds bulk to the load.
The bulkier the powder, the lower the pressure, all things being equal. BUT, the same amount of energy.
That means, if they both burn 100% inside the barrel you will get the similar velocities, but different PEAK pressures.
In a .45 barrel, a 40 grain load of 4227 will fill a 1.150 column.
In a .45 barrel, a 40 grain load of 4759 will fill a 1.500 column.
While it may not seem like much, it is the ratio that matters.
1.500 / 1.150 = 1.304
In theory, if the 40 grains of 4759 yields a 35kpsi load, then the 4227 will yield about 45Kpsi with very similar velocity in a rifle barrel.
This is basically how the Powley computer worked with IMR single base powders.
edge.
NOTE: since double base powders have various levels of nitroglycerin, their grain energy is not directly comparable.
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Post by GMB54-120 on Oct 10, 2019 9:31:40 GMT -5
Difference is how the powder reacts under pressure and at what pressure any change might start to happen.
4227 likes to burn at higher pressure. It was a Mag pistol powder from the get go. 4759 like 5744 was made bulky for a reason. So it had reduced load applications in larger cases such as 45/70. Its not as fussy about bullet weight and case volume. 4227 is a good powder if you covered all your bases. Ive talked to a few people that have gotten it to ignite and shoot reliably in the NULAs.
Improve the ignition, use heavier bullets and tight fitting sabots if you want to get the most out of it. One of the things that might be worth trying is a wool wad. Not to create a better seal as much as to create a tiny amount of air space within the "powder column".
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Post by edge on Oct 10, 2019 9:57:19 GMT -5
Since I mentioned Powley above, some may not know what it was. This predates home computers, so Homer Powley came up with a slide rule ( don't get me started  ) to calculate STARTING loads for cartridges. If you handloaded, and maybe had a wildcat what powder and how much do you start with? Powley decided on 45Kpsi as a safe starting load in a modern firearm. at 100% compression. Since we don't have a case, as long as your ramrod goes all the way down, you get 100%+- every time. BELOW is a graphical version: You don't need the volume, because it is 100%. So you decide you want to use 80 grains of powder, with a 300 grain bullet in a .45 barrel 80 grains divided by 300 grains = 0.267 The Sectional density of a 300 grain .45 bullet is 0.204 Draw a vertical line at 0.267, and a horizontal line at 0.204 IN THEORY, where these meet, would be the closest powder to yield 45Kpsi. Say you would rather use 4198, then drop to 70 grains. The Charge to bullet ratio drops to 0.233 and you would be in the middle of the 4198 curve. Some areas are not covered precisely by IMR powders, so you transition from one to the other by adjusting powder or accepting higher/lower pressures. Hodgdon has H322 which fits nicely in between IMR 4227 and 3031 edge.  |
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Post by ET on Oct 10, 2019 15:35:53 GMT -5
Probably thinner for mold release I believe you're right about ease of extraction from mold. Makes perfect sense. |
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Post by ET on Oct 10, 2019 17:18:16 GMT -5
Edge thanks for the refresher course on Powley and burn rates. Something I need to brush up on. GMB54-120 There's nothing I would dispute on what you stated. Using a wad is on my list down the road. I believe I caused some confusion here with wording. I'm not looking at peak pressure but the time it takes to build to peak pressure, Rise time. My understanding was that a slower burning powder would build pressure slower than a faster burning powder. This was not the case with 4227 compared to 4759. The Rise time on the PT graph showed the opposite. Here is where I should have used the word granular size instead of grain. I believe the smaller granular size gets more pieces ignited than the larger grain powder thereby releasing more gas quicker than the larger grain. More gas, more pressure, more accelerated burn. Now once I find the right BP configuration and load resistance for 4227 it's going to be a shooter in my 50. Here's one reason why.  3rd shot for 4759 ended up another target because of range distraction from the activity there. Because of constant interruptions I was constantly checking my bore with the ramrod before reloading. I didn't display this picture right away as I was hoping to have a few more from different tests to display side by side. Here I need to add bullet size for reference, 250FTX |
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Post by mrbuck on Oct 11, 2019 16:11:46 GMT -5
That looks great shooting to me !
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Post by ET on Oct 11, 2019 19:38:43 GMT -5
That looks great shooting to me ! Thanks Mrbuck. It was a good day but they are not always like that. Some days I struggle to stay focused on target now that I've gotten older. But I'm happy with this day's results. |
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Post by GMB54-120 on Oct 13, 2019 10:28:53 GMT -5
Burn rate charts for sabot application are misleading. Just look at Hodgdons www.hodgdon.com/wp-content/uploads/2017/09/burn-rate-color.pdfFor example, in ML applications N120 is not slower than either 4198 and Reloder7 is not faster. Traces have shown this. Other charts list N120 as faster and Reloder7 as slower which overall is more accurate. Even 45/70 load data confirms it. Things get goofy with the sabots. Powder "X" was designed for mag handguns and a bullet thats tight in the bore. Obviously sabots are not nearly as tight. Powders that lend themselves better to shotgun applications or much lower peak pressures than mag pistols are far more forgiving. Recently ive seen some 4227 testing in sabotless 45 and sofar its quite impressive. Sure is sad that they quit making 4759. It was one of the best overall powders for us. Did nothing stellar but did everything pretty well as far as sabots go. The only solid option is use much less N110 until someone works out the kinks in 4227. |
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Post by ET on Oct 13, 2019 11:31:43 GMT -5
Burn rate charts for sabot application are misleading. Just look at Hodgdons www.hodgdon.com/wp-content/uploads/2017/09/burn-rate-color.pdfFor example, in ML applications N120 is not slower than either 4198 and Reloder7 is not faster. Traces have shown this. Other charts list N120 as faster and Reloder7 as slower which overall is more accurate. Even 45/70 load data confirms it. Things get goofy with the sabots. Powder "X" was designed for mag handguns and a bullet thats tight in the bore. Obviously sabots are not nearly as tight. Powders that lend themselves better to shotgun applications or much lower peak pressures than mag pistols are far more forgiving. Recently ive seen some 4227 testing in sabotless 45 and sofar its quite impressive. Sure is sad that they quit making 4759. It was one of the best overall powders for us. Did nothing stellar but did everything pretty well as far as sabots go. The only solid option is use much less N110 until someone works out the kinks in 4227. I'm, inclined to agree with everything you said. IMO 4759 powder was the best choice for the 50 even after formulation change. Hopefully I will see more with further PT testing into other powders that will take a while. Right now with an unconventional BP in my 10ml-II 4227 has a spot for usage even with the 250 bullet. The one remaining question is " How Temp Sensitive is 4227 ? ". |
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Post by GMB54-120 on Oct 13, 2019 15:11:57 GMT -5
My personal but unproven opinion....4227 will work just fine with the right breach plug and primer. Getter lit up good and its a go especially with a 300gr bullet in a good snug sabot.
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Post by edge on Oct 13, 2019 15:36:48 GMT -5
I have a friend that has used 4227 exclusively in his stock Savage since about 2005, I think he uses 250 SST's in black sabots.
Never a misfire. I never asked if it was IMR or Hodgdon.
edge.
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Post by ET on Oct 13, 2019 17:48:06 GMT -5
Here’s my take on 4227.
When I first shifted from inline ML to SML I also carried the thought of not having a tight load with 250gr bullet and sabot. Yes, I had a few misfires and went to 4759 that seemed to ignite every time. Also staying on the lighter side of load resistance it was easier to seat the sabot/bullet.
IMO 4227 needs to have a good ignition and burn start before the load moves (250/sabot) and the extra load resistance provides that. We are talking of say 25-30lbs of load resistance. Here you need a stiff ramrod with an aid such as a T handle to seat that load on the powder and add some additional compression to pack it together. What I also expect to see in the 50 with a standard BP is a slower rise time on the PT graph because of the larger chamber.
We shall see if my thoughts hold water when I get to that part of testing, chuckle.
Ed
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) to calculate STARTING loads for cartridges.