In the past when confronted with heavy fouling in big BP cartridges I have resoting to duplexing for hunting loads. Anyone have any other techniques once you have explored all the compression/powder manufactuer/granulation options?

My duplex formula is pretty simple and I have used this with everything from 45-100 to 50-2.5 (50-90). In the 50 I use 5grs of AA 5744 in the bottom of the case this is about 17% of the max charge in AA's old manual ( (You need to Login or Register to view media files and links)) I then put in a BP charge of 85% or less of the max I can get in the case with my usual compression. It might be as little as 75% of the BP max depending on the bullet. On top of the compressed powder I put in a milk carton wad followed by a baking paper disc and then a 450gr Govt bullet cast 22:1.

This has worked well in the past but I am wondering if there is another technique I may have missed that will work for hunting/multiple shots when wiping is not an option.

SS

I have never come close to 25% and 5grs is more than adequate in the big cases.

SS

Back when original actions or Shilo were the only option and 45-70 was about the only cartridge brass readily available for long range (1,000 yards) shooting, the Canadian rules allowed 25%, but they were nearly all shooting Martini target rifles.    I'm not sure how they settled on that amount.  Most of the Americans were using original actions and didn't go past 10-15% of total load by weight.  I used 8-10 grs Reloader 7 or 4759 with 65 grs of FFg Goex in my 45-70.  It was shooting in the low 1400s.

I use as little as 3gr of H4198 to clean up my hunting loads in 45-70