what % of ffg to substitute for fffg

[wabi]

Sighted my T/C NewEnglander in with 320 grain Lee REAL bulletsand 85 grains Goex ffg.I'm thinking of switching to Goexfffg since I have a few pounds of it on hand, and am running low on ffg. Would 70 grains be a reasonable starting point to duplicate ballistics?

[cayugad]

70 grains would be a more then reasonable starting point. You might find though that there will be little difference in the volume of powder with the accuracy of the two loads. Also the fffg will produce normally less fowling. So start at 70 and then re work your load up. It will work just fine I suspect.

[SmokepoleStuffer]

Wabi,
Go easy on the FFFG powder increase your load in small amounts. The FFFG powder WILL generate More presure than the FFG will. I shoot a TC hawkins .50 call thats rated for 120 gr of FFG. My FFFg load is only70 gr. I also suggest you do some research.look for stuff written by or edited by Sam Fadalla. I've found his load data is good and his research methods are sound.

Smoke

[cayugad]

The general rule of thumb for difference is 10-15% difference. So 85 grains minus 15% is still 72.25 grains of powder. I do not get too worried about shooting FFFg powder. I shoot it in 90% of my rifles from .50 caliber all the way up to .62 caliber. I have one Renegade that I shoot 100 grains of Goex 3f and a patched roundball and have never had any problems. I would not be surprised if the rifle does not tune in around 85 grains of the FFFg as well as it did with the FFg. You are going to get a little more barrel pressure. But it sounds like you have lots of experience with the FFFg powder as well.


I think the max load is 120 grains of FFg which would still put FFFg at 102 grains of powder.

[wabi]

Thanks for the replies.
I'm not really too concerned about pressure as the charge I'm using now is well below maximum. I've used 80 grains of fffg in that rifle with a round ball load, and it was a good load. Not too hot, but enough to get the ball out with some authority. As I recall, back when I started shooting muzzleloaders (1970s) most shooters used fffg in everything up to .54 cal. at the shoots I went to.
I hope I can get out to try it out this weekend. If the weather cooperates I may take my son (7 years old) camping, and my favorite campsite is about 50 yards from the shooting bench.

[cayugad]

sounds like a great time.. a camp out with your favorite hunting partner, and a shooting range easy to get to. Must be a wonder place.

[Ridge Runner]

the going rate is 90% of fff in place of your standard load of ff