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Post by rbinar on Jul 8, 2009 6:31:09 GMT -5
At the www.shootingandrocketfuels.com/ web site there are some hidden pages. I've recently added to the Gunsmithing page that can only be entered at the bottom of this page www.shootingandrocketfuels.com/index_files/page0001.htm. There are other changes such as added pictures, factual up dates and idea editing. Some you'd notice some possibly you'd not. However this post is about the "Al about pressure" page and the three page back door you can only enter at the bottom of the page called "Theory of Operation". Specifically the post concerns what happens when a duplex load is shot. It is important to me for shooters to understand all loads are a compromise and what compromise(s) is made when shooting a duplex. When shooting a duplex you gain a number of advantages. The load level can now be a perfect match of powder and pressure requirements. Also because of the nature of the load a great deal of adjustment is had and that makes an optimum load more likely. With advantages come compromises. The most obvious has the shooter load the charge in two parts. That alone is enough deterrent to many.A duplex also means that maximum speed will not be achieved by the primary powder as compared to a single powder load. That's not an issue if the maximum speed of the single powder is well beyond what level is desired. But it could become a problem is some limited circumstances. If you take H4198 shooting a 300 grain bullet in the 50 caliber bore making it a duplex reduces the maximum bullet speed. This is hardly a problem when considering a 10/60 N110/H4198 duplex will shoot to about 2450fps. Few would want to shoot a 300 grain bullet to over 2500fps but if desired the duplex would actually slow the load down. The same pressure could be shot with H4198 and 70something grains of powder to a faster speed at the same pressure. In our above example few if any care. Do you want to go 2500+fps with a 300 grain bullet? However in 40 caliber a powder like Varget might bring another reaction. I've seen Varget duplex-ed at 7/63 and another level. This comment is not any criticism of that load but at 2750fps it should be obvious a faster single load is possible with Varget. How much faster is not known because no one has tried to determine maximums at a given pressure. So every load is a compromise. The idea is to choose the compromise that's the closest to what is wanted in the final result. |
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Post by edge on Jul 8, 2009 7:38:56 GMT -5
FYI, I went to the range the other day hoping to test some new sabots. The bullet is the 200 grain SMK with a BC of 0.520 the sabot and wad weigh 30 grains. I ran a few different loads through Quickload to find starting and upper range loads. I was looking for a max pressure between 45kpsi and 50 kpsi which is safe FOR MY RIFLE, and I don't know it is safe for anyone else! I also have a breechplug that uses a vent liner and a bushing so ignition is probably harder in my rifle than your so your pressures would be higher than mine! I have a very hard tome igniting H4198 in standard loads...don't try my loads! At any rate, Quickload gave me 45k for 80 grains, 47k for 85 grains, and 51k for 90 grains. Quikload also predicted 2995 fps, 3084 fps, and 3178 fps respectively. After trying several other loads I shot the 80 grain load and got this trace:  I shot a couple of more with about the same result. I decided that a straight load was not going to work with this powder in my system so I experimented with some duplex loads. I ended up with 5 grains and 80 grains and this is a representative trace:  I will tweak the load for best accuracy, but IMO without duplex this powder would not be a good candidate for my rifle. It may work for someone else's but this shows how duplex loads can be beneficial. edge. |
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Post by KerryB on Jul 8, 2009 8:42:04 GMT -5
Edge,
That is extremely informative and should also serve as a warning to all duplex shooters as to the consequences a very tiny amount of booster can have on pressure levels. Excellent graphics as well...........i always enjoy looking at pressure trace data. Thanks! KerryB
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Post by ewc on Jul 8, 2009 8:58:50 GMT -5
Yes, but actual pressure is still within 2,000 of what quickload predicted for 85 gr.
Edge-
Any idea what quickload would predict for 76, 78, and 80gr Varget in the .40 with a 200sst?
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Post by fishhawk on Jul 8, 2009 9:39:20 GMT -5
Edge, your .520 bc bullet caught my eye, I assume this is an 8mm. SMK. What twist are you shooting to stabilize this bullet? I would think it would have to be quicker than normal muzzleloader rates.
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Post by edge on Jul 8, 2009 10:17:15 GMT -5
ewc, please understand that these are purely predictions and that if the velocities are not similar that the pressures will not be either!
With that said:
In a 40 caliber with a 200 grain bullet Quickload predicts:
Varget Powder
76 grains 39,447 kpsi @ 2717 fps
78 grains 40,605 kpsi @ 2754 fps
80 grains 41,779 kpsi @ 2791 fps.
fishhawk, yes it is an 8mm SMK and the barrel is a 1:14 twist.
edge.
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Post by edge on Jul 8, 2009 10:35:33 GMT -5
I was not trying to hijack the thread, just to illustrate what RB was discussing concerning Duplex  Most of us are using bullets that are so light for caliber that powder just does not burn efficiently. Duplex, with care, you can tweak your loads in an almost infinite amount edge. RB, nice job on the website. A suggestion though might be a return to the first page, or Home page so that you don't have to go back a page at a time OR is this because I am using Iexploder 8 ?? |
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Post by Richard on Jul 8, 2009 13:29:57 GMT -5
RB...........very nice article on rifle building!
Richard
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Post by edge on Jul 8, 2009 14:54:11 GMT -5
The cursor is approximately where the bullet leaves the barrel. The duplex should be close. Quickload predicts 0.308 ms for peak pressure and 0.977 for barrel time. The straight load predicts 0.385 ms peak and 1.126 edge. The Diamonds on the bottom are supposed to be vibration nodes. Supposedly you you should get less dispersion if you hit one of the nodes. www.the-long-family.com/OBT_paper.htm |
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Post by rbinar on Jul 8, 2009 20:11:59 GMT -5
I was not trying to hijack the thread, just to illustrate what RB was discussing concerning Duplex edge. RB, nice job on the website. A suggestion though might be a return to the first page, or Home page so that you don't have to go back a page at a time OR is this because I am using Iexploder 8 ?? I'm very glad you did introduce the trace because it illustrates what I'm trying to say very well. Because of the game (mostly deer) and nature of the bullet (unheard of light weight for the caliber) many loads are simply not going to work without duplex. For the most part we are trying to shoot pistol weight bullets in a rifle environment. That's a challenge. Most pistol cases rely on a very firmly crimped case for results especially when a large volume of powder is attempted. That's impossible with a muzzle loader and can lead to instances just as you describe. On the other hand a powder like Varget may work as expected at 80 grains in the 40 caliber bore. That would still be really low pressure but at a speed (bullet) we can live with. As far as the pages go in the web site. I guess you can mark that off to the web designer. He was trying to make it so there would be fingers that branch off the normal site and lead into nooks and crannies. He felt that might provide users who had seen the site before a reason to re-examine pages from time to time. It may not be a very good idea to make the browsers back out of the corners so the web designer needs to rethink that plan. I'll probably have to set down and have talk with me.... oops. Anyway I can change it. |
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Post by rbinar on Jul 8, 2009 20:21:09 GMT -5
RB...........very nice article on rifle building! Richard The rifle building article is almost done. There will be one last page added to it on bolt disassembly, replacing the cocking sleeve and pin, and jeweling the bolt. The written part of the site is about 60% done. However the video is less than 5% finished so I'd better get to work if it's ever going to be finished |
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Post by rbinar on Jul 8, 2009 20:27:10 GMT -5
ewc, please understand that these are purely predictions and that if the velocities are not similar that the pressures will not be either! With that said: In a 40 caliber with a 200 grain bullet Quickload predicts: Varget Powder 76 grains 39,447 kpsi @ 2717 fps 78 grains 40,605 kpsi @ 2754 fps 80 grains 41,779 kpsi @ 2791 fps. edge. These are probably close but I'd start at 72 or 73 grains and go up if (and only if) bullet speeds confirm the estimate. I've shot Varget at 72 grains and you can expect it to ignite even at this level so there is no need not to approach a load from below. If it really shoots 2850fps at 82 grains that would be a very good place for a single. |
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Post by ewc on Jul 9, 2009 7:15:44 GMT -5
RB-
I've shot it to 71 gr, but did not get a speed. 69 gr gave me 2,605.
I plan to shoot tomorrow and I will time it from 72-82 (assuming my speeds are close to predicted speeds from Edge).
I may have to buy that Quickload program - seems like a very handy tool.
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Post by edge on Jul 9, 2009 7:53:07 GMT -5
FYI, Quickload predicts 69 grains of Varget will shoot the 200 grain bullet to 2550 fps @ 33,697
You got 2,605 so backing that out I would get about 37,500 kpsi.
Just remember if the velocity moves higher than 2700 before you hit 75 grains that the pressure will probably be over 40kpsi too.
edge.
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Post by ewc on Jul 9, 2009 8:03:44 GMT -5
Thanks edge. Where did you get the Quickload?
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Post by edge on Jul 9, 2009 8:11:33 GMT -5
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Post by chuck41 on Jul 9, 2009 11:31:14 GMT -5
IMO it is overpriced @ $150. but it is handy. . . . . . . . . . . . edge. I think I can do without it at that price. I primarily use Varget as a duplex load of 7gr 4759 with 63gr Varget for a total 70 gr load. On my chrono with a 200gr XTP that reads right at 2750fps. My chrono shows a huge decrease in velocity when it is used as a single powder load. I suspect that, at least in my rifle with the level of knurling I typically use, that Varget needs the assistance of the igniter for reliability with 200gr bullets. Heavier bullets might perform differently, but they are hard to come by in a .400" diameter unless you are willing to do some modifying of them. I have a handful of 300gr Hornady .411" interlocks and have resized some of them. Will give them a try one of these days. Edge, what would your Quickload predict for a 300gr 40cal bullet using Varget or H4350? Ought to be good for Elk, . . . . or Moose. |
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Post by edge on Jul 9, 2009 12:45:05 GMT -5
IMO it is overpriced @ $150. but it is handy. . . . . . . . . . . . edge. I think I can do without it at that price. I primarily use Varget as a duplex load of 7gr 4759 with 63gr Varget for a total 70 gr load. On my chrono with a 200gr XTP that reads right at 2750fps. SNIP I have a handful of 300gr Hornady .411" interlocks and have resized some of them. Will give them a try one of these days. Edge, what would your Quickload predict for a 300gr 40cal bullet using Varget or H4350? Ought to be good for Elk, . . . . or Moose. First, when I saw the 70 grains of powder I thought that seems like it would produce high pressure. However, 4759 is a very bulky powder, as a matter of fact your 70 grain load actually takes up the room of almost 80 grains of straight Varget....which should get you in that velocity range and at a pressure +- 40kpsi. The 300 grain bullet with 60 grains of Varget should get you around 2,200 fps @ 40kpsi. 80 grains of 4350 should get you 2,400 fps @ 40kpsi. edge. PS those are estimates only and should be worked up to with a chron. |
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Post by Dave W on Jul 9, 2009 18:24:00 GMT -5
The cursor is approximately where the bullet leaves the barrel. The duplex should be close. Quickload predicts 0.308 ms for peak pressure and 0.977 for barrel time. The straight load predicts 0.385 ms peak and 1.126 edge. The Diamonds on the bottom are supposed to be vibration nodes. Supposedly you you should get less dispersion if you hit one of the nodes. www.the-long-family.com/OBT_paper.htmInteresting read. I have wanted to get Quickload for a long time but I don't think I can convince the wife that I really need it, guess I'll have to continue using the eye test and chrony to gauge if I'm getting a good burn on the powder. That duplex trace is a real eye opener, hard to believe 5gr of booster changed the pressure that much. Glad I start conservatively when in unchartered waters. |
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Post by rbinar on Jul 9, 2009 19:21:01 GMT -5
First, when I saw the 70 grains of powder I thought that seems like it would produce high pressure. However, 4759 is a very bulky powder, as a matter of fact your 70 grain load actually takes up the room of almost 80 grains of straight Varget....which should get you in that velocity range and at a pressure +- 40kpsi. edge. OK since I'm confused I'll have to play the dog and bite on the bait. How much difference would there be in a 70 grain load with duplex (W=81.72) and a single powder shooting the same speed (W = 78.91)  70 grains of powder at 2750fps seems almost anemic to me in any powder combination. I regularly shoot 60 grains of Benchmark at 2615fps: 10 grains more (17%) isn't supposed to shoot at least 150fps faster? |
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Post by jims on Jul 9, 2009 19:37:21 GMT -5
I like getting all this .40 load information, everybody keep us the good work.
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Post by ewc on Jul 9, 2009 20:20:03 GMT -5
"Interesting read. I have wanted to get Quickload for a long time but I don't think I can convince the wife that I really need it, guess I'll have to continue using the eye test and chrony to gauge if I'm getting a good burn on the powder.
That duplex trace is a real eye opener, hard to believe 5gr of booster changed the pressure that much. Glad I start conservatively when in unchartered waters. "
DaveW-
I may be confused, but QL predicted 47 and his actual was 49. How is this significant?
A question to edge via pm - QL does not predict using temp and elevation.
These could attribute to the 2,000 difference.
Either way, its not that big of a deal.
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Post by Dave W on Jul 9, 2009 20:59:24 GMT -5
"Interesting read. I have wanted to get Quickload for a long time but I don't think I can convince the wife that I really need it, guess I'll have to continue using the eye test and chrony to gauge if I'm getting a good burn on the powder. That duplex trace is a real eye opener, hard to believe 5gr of booster changed the pressure that much. Glad I start conservatively when in unchartered waters. " DaveW- I may be confused, but QL predicted 47 and his actual was 49. How is this significant? A question to edge via pm - QL does not predict using temp and elevation. These could attribute to the 2,000 difference. Either way, its not that big of a deal. I was looking at the difference between the single vs. the duplex load and the pressure jump. |
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Post by ewc on Jul 10, 2009 7:04:04 GMT -5
There was also a 5 grain difference between the two traces-
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Post by edge on Jul 10, 2009 8:31:47 GMT -5
OK since I'm confused I'll have to play the dog and bite on the bait. How much difference would there be in a 70 grain load with duplex (W=81.72) and a single powder shooting the same speed (W = 78.91) 70 grains of powder at 2750fps seems almost anemic to me in any powder combination. I regularly shoot 60 grains of Benchmark at 2615fps: 10 grains more (17%) isn't supposed to shoot at least 150fps faster? I don't know exactly, but would expect the duplex to be about 1,000 psi less for the duplex based on the difference in capacity. The 2750 may be Anemic , but probably about 15% higher pressure than the straight Varget, assuming the same volume. By the way Quickload would have predicted 2,570 @ 38,683 for your Benchmark load ( 40 cal. 200 gr. bullet ). edge. |
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Post by rossman40 on Jul 10, 2009 11:37:07 GMT -5
I think part of the super charge effect you see with 5744 as a booster is your dealing with a double base powder. I wonder how much of a change in the pressure curve if you switch to N110 or 4759 which are single base with lower burn temps.
While duplexing gives you the option of customizing the pressure curve, how each combination interacts is new territory. You just can not go by a burn rate chart and chrono readings and the fact it didn't blow a sabot (if your shooting sabots). I think looking for the the right (and safe) combo should be approached carefully and the pressure trace is a great tool. Quickload can guesstimate pressures of single loads but when you start duplexing your stepping into the twilight zone. I think Edge's example of the 5744/10X combo shows how easy it is to get into the danger zone.
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Post by Dave W on Jul 10, 2009 17:33:52 GMT -5
If you don't mind Edge, what was the weight of the sabot/bullet and the speed on the 80gr 10X charge?
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Post by chuck41 on Jul 10, 2009 17:41:45 GMT -5
. . . . . . . . . . . While duplexing gives you the option of customizing the pressure curve, how each combination interacts is new territory. . . . . . . when you start duplexing your stepping into the twilight zone. . . . . . . . . . . . I absolutely love the reliability I get from duplex. I know that with it I will get a load that will go "Boom" every single time, even if the main powder is a slow burner and I am near the bottom of the pressure curve for it with the light bullets I use. That is something I have not always gotten when trying to use some of the slower burning powders by themselves. However, I think Rossman is absolutely on target here. Duplex can be a complex thing to fool around with and definitely puts you in "new territory" where extreme caution is advised. A faster burning powder will get the desired quick rise in pressure, but there is a lot of art to tailoring the exact proportions of each component to get a reliable load that is also safe to use for load, after load, after load. Don't know 'bout you but I am not super comfortable traveling in "new territory". As a result I will be using the smallest amount of the igniter powder that gives me reliable and repeatable results combined with careful examination of chrono results and spent primers for possible signs of pressure. If I had the luxury of a pressure trace you can bet I would be using that sucker too!! If my "go to" load turns out to be just a bit on the anemic side for the powder(s) I am using, so be it. There is way more killing capability in a 40 cal Savage/PacNor than is really necessary for the size deer usually found in my back yard anyway. |
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Post by edge on Jul 10, 2009 19:28:51 GMT -5
If you don't mind Edge, what was the weight of the sabot/bullet and the speed on the 80gr 10X charge? The bullet, sabot and wad weigh a combined 230 grains. I still have not worked out a setup for chronographing with fluorescent lights yet....someday soon For now I'll deal with pressure and accuracy. When those are ironed out I'll go to an above ground range and get the velocity. Pressure trace does give approximations and they are generally in the ballpark. I like what I saw so I made some more sabots and will try some powders in the general range as 10X but slightly slower. ( 2015 and H322 ) I would prefer to stay in the 3,000-3,100 fps range and keep pressure 45kpsi +- a couple. edge. |
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Post by Dave W on Jul 10, 2009 22:44:52 GMT -5
If you don't mind Edge, what was the weight of the sabot/bullet and the speed on the 80gr 10X charge? The bullet, sabot and wad weigh a combined 230 grains. I still have not worked out a setup for chronographing with fluorescent lights yet....someday soon For now I'll deal with pressure and accuracy. When those are ironed out I'll go to an above ground range and get the velocity. Pressure trace does give approximations and they are generally in the ballpark. I like what I saw so I made some more sabots and will try some powders in the general range as 10X but slightly slower. ( 2015 and H322 ) I would prefer to stay in the 3,000-3,100 fps range and keep pressure 45kpsi +- a couple. edge. Thanks. You have probably seen this: www.shootingchrony.com/products_ACCESSORIES.htmDon't know if it is feasible for your range but one of the local bow shops used it for indoor shooting. |
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