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Duplex loads Help needed

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Dale Clifford View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dale Clifford Quote  Post ReplyReply Direct Link To This Post Posted: June/27/2007 at 20:31
gee whats a little hot sulfuric and nitric acid compared to a 6lb grenade frag.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote pyro6999 Quote  Post ReplyReply Direct Link To This Post Posted: June/27/2007 at 20:38
you know i was asking a friend of mine who is older than me by more than 10 yrs if he had heard of the whole duplexing thing and he told me he's very sure that a lot of the gun powders on the market today already are duplexed, we both agreed that there isnt really any need to try such a dangerous practice with the huge versitile lineup of gun powders we have today he said in the 50's and 60's we didnt have sh*t for powder compared to half the stuff we have today so yeah back  then sometimes you would do it to get a desired result, and unless your a pretty good chemist your liable to end up missing limbs fingers eyes  oh maybe your house and your next door neighbors.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8shots Quote  Post ReplyReply Direct Link To This Post Posted: June/28/2007 at 08:23

OK, I made it! I have tested the following loads this morning (all at 89,5mm OAL) with 200gr Nosler Part.

67 gr S385 The max the manuf recoomend, which should give 2750 fps

67,5 gr S385

68gr S385

60 gr with 40% S385 and on top 60% S365 held down by toilet paper.

Two fouling shots with 165gr Spartan bullet.

 

The following interesting facts emerged:

The 68 gr gave the best group indication with 1/2 inch grouping.

The rifle seems to throw one bullet centre high, one centre right and so it continues. The two fouler shots did not do this. It could be that I am flinching on each second shot. I shoot two, mark them and shoot the next two. The rifle has a solid kick on these loads. The trigger is also still an issue.

The one shot of 111 was pulled. That was the first of the 111.

The duplex load gave a nice recoil feel to the rifle, very smooth.

Toilet paper in front of 60gr of powder gives a nice snowfall effect!!

 

I will be hunting again on 6 Jul and will stick with 68gr S385 behind a 200gr Nosler Part with OAL at 89,5mm.

Bring on the big bulls!

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Dale Clifford View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dale Clifford Quote  Post ReplyReply Direct Link To This Post Posted: June/28/2007 at 10:38

a lot of powders today are double based, nitrocellulose , and nitro so technically they are duplex-- the older slang term has a different meaning however.  a smart chemist never, never, plays with anything with more than 2 oxygen molecules in concentrations greater than .0001.

a short time after the duplex craze, there were some people selling "inhibitors" which when sprayed on a fast index powder, slowed the index.

as hot30 puts it-- the "pucker" factor is just to high

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8shots Quote  Post ReplyReply Direct Link To This Post Posted: June/28/2007 at 10:46

Thanks for your words of caution. Maybe that is why someone suggested I use toilet paper in stead of Dacron as a filler!!!

I will just stick with the single powder loads.

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303Guy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 303Guy Quote  Post ReplyReply Direct Link To This Post Posted: September/02/2007 at 13:59
Originally posted by 8shots 8shots wrote:

Does anyone have experience with duplex loads? Mixing fast burning and slow burning powder to obtain a more efficient one for a particular rifle?.......

The idea behind this is to give good speeds with good bullet stability.

Any information or advice will be welcome.

 

Hi there 8shots. 

  I can only say yes and no.  Yes, because I did it for the first time yesterday.  It sounds like you are in my old country.  Ok, like the others have said,  DO NOT USE DOUBLE BASE POWDERS!  And do use plenty of caution.

   My experiments were with two rifle powders.  My theory was that if my AR2205(H4227)  -  close to MP300 - was topping out with heavier bullets at a cirtain load, then by reducing an amount of that powder and replacing the volume with a slower powder AR2208(Varget)  -  close to MR200 - then I would lower the pressure.  I started by replacing about 10% AR2205 with AR2208 and ended up with a charge of 60% AR2205 and 40% AR2208.  I weighed the AR2205 - placed it into the case then filled the remaining space with AR2208. I then poured that out, mixed it and put it back in.  That left more space as the spaces between the larger granules filled with the smaller ones, so I added more AR2208 untill the case was full enough to slightly compress the powder.  The idea was to prevent segregation of the two powders from shaking.  I did all my test firing into a firing tube with damp sand in the trap at the bottom.  The only velocity indicator I had was the degree of disintegration of the bullet.  The final load gave me total lead loss.  This showed that the final velocity achieved is way higher than with AR2205 alone.  At all times, I was checking for pressures and at all times, pressure signs were LESS than with the top AR2205 load.

 

A bit long-winded here - sorry about that!

 

My objective?  To stabilize a 55gr bullet in my hornet!

 

 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8shots Quote  Post ReplyReply Direct Link To This Post Posted: September/03/2007 at 09:33

Hi 303Guy,

I live and hunt in South Africa. Thanks for sharing your experience on duplex loads. The recipe I tried also worked and certainly the recoil felt less severe then on other loads. Obviously this is very unscientific and the only factor I measured was grouping/accuracy.

I have however found a straight load that works, and quite frankly I cannot see myself measuring out two loads for each round. Way too time consuming! But an interesting concept never the less.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 303Guy Quote  Post ReplyReply Direct Link To This Post Posted: September/05/2007 at 13:48

Hi  8shots

 

I was from the old Natal - Pietermaritzburg and Zululand before that.  I am in New Zealand now.  Our hunting is a little bit wetter than yours!

 

You are right about the effort!  I can measure the one powder but have to weigh the other.  I can use Lil'Gun to achieve the same end - which I will.  But is was fun.

 

Regards

303Guy

 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dale Clifford Quote  Post ReplyReply Direct Link To This Post Posted: September/05/2007 at 14:23
you guys are crazy-- orginal duplexing gave a lot of emphazise to maximize segregation
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 303Guy Quote  Post ReplyReply Direct Link To This Post Posted: September/06/2007 at 02:48
Originally posted by 8shots 8shots wrote:

......

PS What is unique powder?

 

Hi 8shots

 

I didn't see whether anyone answered you.  It very similar to MP200 - small pistol powder.  It is a double base powder containing nitro-glycerine.  In duplex loads, it was used as a 'primer' to ignite slower powders in magnum cases.  That is dangerous territory!  But it can used to clean up black powder cartridges, although I think they use shotgun powders like Bullseye - similar to MS200.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 303Guy Quote  Post ReplyReply Direct Link To This Post Posted: September/06/2007 at 02:59

Originally posted by Dale Clifford Dale Clifford wrote:

you guys are crazy-- orginal duplexing gave a lot of emphazise to maximize segregation

 

If I wasn't crazy, I would go insane!

 

Hi Dale

 

You are right.  Those guys were using double base powders to ignite single base powders.  They were crazy!  And bold.  I believe some of them lived.

 

What we tried was substituting some of the 'normal' charge of a fast rifle powder with a quantity of slower rifle powder to reduce pressures and/or increase velocity without raising pressures.  I seriously don't think it to be any more dangerous than reloading itself - which is dangerous.  Not as dangerous as driving a car 'though.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote pyro6999 Quote  Post ReplyReply Direct Link To This Post Posted: September/06/2007 at 16:55
lets try bullseye and r-25!!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dale Clifford Quote  Post ReplyReply Direct Link To This Post Posted: September/06/2007 at 21:18

What we tried was substituting some of the 'normal' charge of a fast rifle powder with a quantity of slower rifle powder to reduce pressures and/or increase velocity without raising pressures.

 

oh I understand the theory alright, the same reason I used to dip M-80's in epoxy and get the neighbor kid to light them off. or I think I'll smooth out the irregularties in the extreme spread in this lot of varget with soem 4350.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 303Guy Quote  Post ReplyReply Direct Link To This Post Posted: September/07/2007 at 02:43

Originally posted by Dale Clifford Dale Clifford wrote:

....... orginal duplexing gave a lot of emphazise to maximize segregation

 

I just couldn't stop while I was still ahead!  I just had to try segregating the powders.  I first loaded up a test with the slower powder first.  Less pressure, so I tried the slower powder last.  Still low pressures but the partially burned powder kernels have a massive kinetic energy!  I kept the powders separate by compressing the load.

 

So it seems that maximum pressures are achieved by mixing the two powders.

 

Just for the record - I am NOT promoting this practice.  It CAN be dangerous!  It is in any case, just way too much trouble.

 



Edited by 303Guy
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 303Guy Quote  Post ReplyReply Direct Link To This Post Posted: September/07/2007 at 02:50

Originally posted by pyro6999 pyro6999 wrote:

lets try bullseye and r-25!!

 

I don't even want to know what would happen!

 

I did read of someone testing the strength of a Arisaka action.  This guy jammed a bullet in the throat, filled the case with Unique, topped with a bullet and fired it remotely.  He reported that the case was extruded all over the inside parts of the action (which had to be opened with a hammer) but the action was otherwise intact!  (Don't try this at home)!

 



Edited by 303Guy
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 303Guy Quote  Post ReplyReply Direct Link To This Post Posted: September/07/2007 at 02:55
Originally posted by Dale Clifford Dale Clifford wrote:

...... the same reason I used to dip M-80's in epoxy and get the neighbor kid to light them off......

 

Did the neighbor's kid survive?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dale Clifford Quote  Post ReplyReply Direct Link To This Post Posted: September/07/2007 at 09:06
Ya, he just wanted more money.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 303Guy Quote  Post ReplyReply Direct Link To This Post Posted: September/19/2007 at 03:22

8shots,  I just had to do some more experiments with duplexing!  This time I placed the slow powder over an amount of the fast powder then the rest of the fast powder on top.  That was mainly to blow the partially burnt kernels out the barrel.  Works real well!  I found that the lighter the bullet, the lower the slow powder ratio must be for decent combustion.  I have been able lower the pressure of my hottest load without loss of velocity.  (Using penetration and impact tests for comparison).  I worked up a load that filled the case enough to hold the powder tight to prevent mixing.  I have loaded up some rounds for range testing - prelimanary tests in the field look good.  Of course, this is for fun   - way too much trouble and off the shelf powders available that cannot be beat!

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bigdaddy0381 Quote  Post ReplyReply Direct Link To This Post Posted: September/19/2007 at 08:11

  What are you guys useing as a FILLER for when powder dosen't fill the case up???????

whats the pro's and con's of useing it.

 

BIG



Edited by Bigdaddy0381
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 303Guy Quote  Post ReplyReply Direct Link To This Post Posted: September/19/2007 at 13:58

Bigdaddy0381,

for safety sake, I am not recommending it, but...  I do not use a filler - the slower powder is the filler!  In my case, I find the maximum normal powder charge for that bullet then substitute some of it with the slower powder until I fill the case without raising pressures.  The idea of placing the slow powder over the primer was to gain more burn time and less ejecta velocity but then the powder remains in the bore so I place a little 'normal' powder over the primer first.  That gives me good burning and clean bore.

As to the pros and cons, well there are no real pros except for the fun and the fact that I can use my existing powders to gain max performance with a heavy bullet.  That proves to me that I can now go and spend my money on the right powder - that being Lil'Gun in my case.

The cons are simply a lot of effort!

From a safety aspect, consider that I am doing this in a hornet using a normal hornet powder in conjunction with a slower powder - no small pistol powders involved!  The hornet case is a lot safer to play with than a larger case.  For starters, the base-line pressures are low.  I also tried the three modes of adding the powder to find the worst case.  Slow powder over primer,  slow powder last and mixed.  Mixed gave highest pressures.

 



Edited by 303Guy
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