Which powder for duplex load?

This is the place to discuss your duplex and smokeless loads for your black powder guns. All SAFETY concerns must be addressed, and high pressure loads are NOT to be promoted here.
PostsCOLON 16
JoinedCOLON Fri Feb 22, 2008 7:16 pm

Which powder for duplex load?

Post by juanvaldez » Tue Jun 01, 2010 4:58 pm

Shot some today.cant believe how clean the gun was. I have 2400, H4198, unique, varget, H322, H110, H4227, Benchrest, H4895, Tite Group all on hand. I want to go 55 grains of 2f over 5 grains of ?? Rifle is a 45/70

Last edited by 1 on juanvaldez, edited 0 times in total.

John Boy

Re: Which powder for duplex load?

Post by John Boy » Tue Jun 01, 2010 6:35 pm

I want to go 55 grains of 2f over 5 grains of ??
For what cartridge caliber?

PostsCOLON 16
JoinedCOLON Fri Feb 22, 2008 7:16 pm

Re: Which powder for duplex load?

Post by juanvaldez » Tue Jun 01, 2010 6:50 pm

Guess that would help...45/70

PostsCOLON 274
JoinedCOLON Tue Nov 29, 2005 4:02 pm
LocationCOLON WI

Re: Which powder for duplex load?

Post by beltfed » Tue Jun 01, 2010 8:07 pm

When I was duplexing the 45-70 , I used 6 grains of IMR4759 under 61 gr of Goex FFg. Ave Vel 1256fps.It shot well to 1000yds.

From what you have on hand I would use the IMR 4227. - similar burn rate to the 4759, but less bulky.


PostsCOLON 293
JoinedCOLON Fri Dec 16, 2005 12:35 am

Re: Which powder for duplex load?

Post by zrifleman » Tue Jun 01, 2010 11:54 pm

IMR 3031. Tried the others but 3031 does it better for me. My pet duplex load in a 45-70 with standard chamber is 540 PJ or Brooks with 62-63 grs of Goex 1 FG, 6 grs of IMR 3031, .030 wad, compress bullet to fit, WW brass, Fed 150 or RP LP primer. Chronographed velocity is 1210-1220 fps.

PostsCOLON 25
JoinedCOLON Sun Jan 31, 2010 4:30 pm

Re: Which powder for duplex load?

Post by NickSS » Thu Dec 16, 2010 7:45 pm

I tried several powders in a 45-70 for duplex loads all with more black than you want to use. I found that stick powders worked better than ball powders and that I got good results with both 4198 ans 4227 using six gr or either and 60 to62 gr or FFG GOEX. I was using a Lyman 457125 at the time cast from range scrape. This was early in my BPCR shooting before I got more knowledge and went to straight black powder and known alloy bullets.

PostsCOLON 6
JoinedCOLON Fri Apr 20, 2012 10:02 am
LocationCOLON central alaska

Re: Which powder for duplex load?

Post by bigted » Fri Apr 20, 2012 11:20 am

ive been shooting a bunch of paperpatched bullets with duplex loads. my favorite was the imr 3031 till i tryed the imr 4227 as a duplex behind my blackpowder. very clean and i didnt notice any variation in how the rifle shot or in anything but the cleaniness of the shot...very near smokless in clean but i still get the 'bump' of bp and the shower of sparks n smoke with all the benefit of shooting smokless. i also shoot very little bore dia but rather groove dia bullets. i paper with onion skin and back up to groove diameter for the final.

also i never use any more then 10% of smokless for the total amount of bp i want to use...like my absolute favorite load consists of 6 grains 4227 with 54 grains goex 2f powder with a 1/8th felt pad over the powder column........so the total is a 60 grain load with it broken down like mentioned.......this combo is what i use to figure loads for a certain bullet...i shovel bp into the case for a total charge up to the compression i desire then use the 10 percent equation to then subtract from the total bp charge ive settled on with the experiment with a dummy case.... i have shot this load thru my ruger #1,,winchester hiwall,,browning bpcr,,marlin model SBL,,pedrosoli long range m- '74',,,all in 45-70 chambering,,,,,,,and my shiloh 45-120 i use the 10% factor but havnt found the sweet spot for it yet.

so when i find a total charge for a certain bullet...judged from where it wants to seat to...i take the bp charge and multiply by .10 to arrive at the sp duplex charge the subtract from the total bp charge ...like this ...charge a case with 2f powder for an amount that settles up to an amount that goes 1/4 inch higher then the seated depth of that particular bullet...lets say that this amount is 68 grains 2f powder...so the equation would go thusely;;

68 multiplied by .10 = 6.8 grains.......now take 68 - 6.8 = 61.2 grains.

so i would take 6.8 grains of imr 4227 and put it in the case first...followed by the 61.2 grains of GOEX 2f blackpowder...followed by the 1/8th felt wad overpowder wad...compress this to the depth needed for seating the bullet to the desired depth. for my singleshot rifles i do not crimp at all nor do i even come close to any damage to the patched outside of the bullet.

now before i do the above i take the case and size it to around .0005 to .001 under the final wrapped diameter of the bullet and ive even gone without any sizing with my groove dia bullets which i desire as they dont get work hardened this way.

whewww this got windy so ill jump off and see what happens.

PostsCOLON 26
JoinedCOLON Fri Feb 24, 2006 11:37 pm

Re: Which powder for duplex load?

Post by mdeland » Mon Aug 12, 2013 1:08 am

One of my favorite loads for 2.1 case (45-70) is 6 grains of Reloader 7 and 60 grains of 2F Goex or Cartridge black a .030 veggie wad and a 500 grain Lyman Schmitzer or 510 grain Paul Jones Creedmoor bullet. My best primers have been CCI BR ll primers. Both these bullets have been quite accurate for me to 600 yards. Mike D.