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Duplex loads Help needed

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/25/2007 at 07:43
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Does anyone have experience with duplex loads? Mixing fast burning and slow burning powder to obtain a more efficient one for a particular rifle?

I have read an article which advocates the mixing of a slower burning powder at 40% by weight and a faster burning powder as the balance. The article states do not mix the powder before weighing, which makes sense. It further states "place the slower burning powder on top of the primer, followed by the faster burning powder". The question now arises, should one fill the shell with dacron to prevent mixing in the shell, or can mixing take place in the shell?

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

Any information or advice will be welcome.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/25/2007 at 08:44
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duplex loads are not recommended by anyone who cares for the people they associate. unless you have the safety equipment a spare duplicate of the firearm and say an Oheler ballistic lab (pressure equipment)

 

duplex loads belong to the era of steel screw on webs, for higher pressure, brass weld primer tubes to bring the flame front to the "top" of the powder charge,

 

if they worked, you can bet competitive long range shooters, would have developed the protocols long ago.

first time I was made aware of duplexing was in the 60's and it hasn't gone anywhere since.,

 

 

 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/25/2007 at 09:26
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Thanks Dale. Then another question. If I am getting a better grouping as I lower the velocity (from 2800fps to 2400fps) on a 308 cal 200gr, would there theoretically (or practically) be a speed beyond 2800fps where the grouping starts to improve again?

As for the duplex load, we have S365 and S385, both recommended for the 300H&H, but the S365 is hotter then your IMR4831 and our S385 is slower again, the claim being that the above can duplicate your IMR4831.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/25/2007 at 09:31
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duplexing experiments in the us -- involve a blast shield and something like 4350 and 10 grs unique. yes a higher velocity can give a more accurate load, this is seen especially in varmint guns.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/25/2007 at 19:50
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sounds crazy to me kids
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/25/2007 at 22:33
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maybe -- but triplexing is really nuts.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/26/2007 at 06:24
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yeah its the stuff they end up using to make a nuke i think
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/26/2007 at 22:20
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8shots, if you insist to persue the duplex loads, snuggle-up with someone from the loading division of a powder and ammo manufacturer..  I shoot my .308 with 45gr of 4350 and Dont try the unique mixer.!!!!!  Bribe your chemist for the rest.

 

       Sorry Dale, but your correct about blast shields etc. if you DO play with unique

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/27/2007 at 02:30
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Thanks for all your words of caution. Playing with this stuff is dangerous.

The duplex load that I am pursuing is using two excisting powders, both which are safe in my 300H&H. The one being S385 which burns slow, and using S365, which burns slightly faster. The maximum load of neither is exceeded. The idea is to use 40% S385 and 60%S365. This should give a slightly more efficient burn in the rifle according to the fundis.

I have taken this up with our powder manufactures, and allthough they cannot endorse it for obvious reasons, they are not concerned that I will blow myself up.

 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/27/2007 at 06:07
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Originally posted by hot30 hot30 wrote:

8shots, if you insist to persue the duplex loads, snuggle-up with someone from the loading division of a powder and ammo manufacturer..  I shoot my .308 with 45gr of 4350 and Dont try the unique mixer.!!!!!  Bribe your chemist for the rest.

 

       Sorry Dale, but your correct about blast shields etc. if you DO play with unique

 

oh the stories my old man tells about garbage cans and other steel containers and unique powder.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/27/2007 at 10:23
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I have made up two rounds on the 40% 60% formula. As we have no blast shields available, I will ask my best buddy to take the first shot. If there are no further postings then you know it was a bad idea!

PS What is unique powder?

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/27/2007 at 10:29
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 8shots

 just tie the gun to a tree stand way way back and pull trigger with string. then have your best buddy fire second shot.



Edited by Bigdaddy0381
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/27/2007 at 11:06
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unique is a med. HANDGUN powder---   plexing was really popular back in the 80's when the guys used to put the guns in old truck tires and fire them with a string from afar. (really -no sh*t)  of course most of the guns were reworked miliary surplus- but none the less.

reminds when I used to talk the neighbor kid into holding on to a pipe while I stuffed an old CC battery and M-80 into it. --- good for about 400 yds.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/27/2007 at 11:16
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  cc battery  awsome.

 

  when i was younger ( lol ) we would take a bowling ball and drop it from 700 or so feet and see if we could hit a car that we parked at the end of the strip to see if we can even hit it. we did once but it wasen't the right car.we hit my buddies wifes car about 100 yards away in there drive way. it smashed it pretty good.we wound up just sticking to sticks of dynomite under the one we should have it and blew it up around midnight that night.we had ever cop withen 20 miles visiting us.

 

It is amazing what wild turkey and friends with out good since will make you do.

 

if i mail someone a pic can they shrink it and add it for me.It was from a few weekends ago.

 

 



Edited by Bigdaddy0381
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/27/2007 at 13:35
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As kids we used to take a half inch galv waterpipe and weld one end shut. A big bang cracker and a marble fitted exactly. This thing would shoot right through a door. Ask my brother, he knows!

Edited by 8shots
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/27/2007 at 13:47
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The "string thing".   Just before you pull the string you still half s--t yourself.. Doesnt matter how many times you do this, ya dont get used to it!!
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/27/2007 at 13:53
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Bigdaddy,  I grew up in the snow belt.  Wait until the snow gets allittle wet  and roll your snowball  down a 4 or 500 ft steep grade.  Time it so ya know who your going to knock off the road though..  After your done kicking the snot out of each other, then its a good laugh..
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/27/2007 at 14:55
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You guys were right, you don't play with unique!!!

 

 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/27/2007 at 14:59
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The "string thing".   Just before you pull the string you still half s--t yourself.. Doesnt matter how many times you do this, ya dont get used to it!!

 

 

 

I know the neighbor kid did!!!!!!

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/27/2007 at 19:55
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I made nitroglyceryn one time when I was 12 or so.

I'd rather do it again compared to playing witha duplex load in a rifle.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/27/2007 at 20:31
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gee whats a little hot sulfuric and nitric acid compared to a 6lb grenade frag.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/27/2007 at 20:38
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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.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/28/2007 at 08:23
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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!

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/28/2007 at 10:38
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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

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/28/2007 at 10:46
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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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