General discussion > Black Powder Shooting

2F to 3F Powder Conversion

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Jefferson58:
Hi Folks:

I expect this question has been answered a 1000 times, but I can't seem to find anything that really gives a clear description:

Is there a good method for determining a comparable quantity of 3F powder to 2F powder? What I am looking for is basically a good rule of thumb for switching powder without drastically increasing pressure. If, for instance, I use 60 grains of 2F in a load and want to shoot 3F instead, is there a certain percentage of 3F to use versus the 2F amount?

Thanks for the help.

Jeff

roundball:
Rule of thumb is to reduce 2F load data by 10-15% to keep pressures in the same ball park...I prefer 3F and use it in .40/.45/.50/.54/.58/.62cals because its always been faster, cleaner, and as accurate or more accurate than 2F for me...both rifles and smoothbores...ie: I just finished sighting in a new .58cal with 100grns Goex 2F deer load, then tried 90grns 3F and will stay with the 3F.

northmn:
My Lyman BP Handbook lists pressure in a 54 in comparison.  120 grains 2f gives 1667 and 80 grains of 3f gives 1629.  Pressure is respectively 8100 LUP for the 2f and 8400 LUP for the 3f.  You are talking here about a reduction of 25%.  They list another example where equal velocities with 140 vs 100 has an increas of the 3f of 3200 LUP.  A 45 had comparative data at 8300 lUP for 70grains of 2F and 8710 for 3f at comparable velocities.  Interestingly the pressures with 2f went higher than 3f with charges over 80 grains of 2f.  2008 fps for 2f at 15100
and 13680 for 70 grains of 3f at 1994.  My guess is that 2f had to push a significanly heavier mass at a certain point.  Unless you have very sophisticated pressure equipment it would be hard to really get a picture.  The old rule of thumb used to be 3f up to 45 and 2f 50 up with a 50 being kind of an either or.  Daryl likes 65 grains of 2f in his 40, I believe.  It is possible looking at the 45 data he may be getting higher pressure than with 3f????? ???  When I chronographed my 54 flinter I got very similar velocity figures to Lymans.  Use about 90 grains of 3f for a hunting load.  It has plenty of power for deer, shoots good and seems "quick".  Mostly it is a matter of keeping loads reasonable and seeing which works best.  Lyman felt that the pressures for 3f were higher but were not significant.  Other options are to use Swiss instead of GOEX etc.
DP

Colonial Riflesmith:
Hi Jeff, I seems these guys know what they are taking about when it comes to heavyer loads and pressures. One thing I've noticed is that shooters on this site seem to like heavyer loads than I'm acustom too. I'm learning a lot from just reading their posts.

Acer Saccharum:
Don't go by what Daryl burns....unless you like a sore shoulder... he likes big bores with lots of powder.... uses about 25 lb a year.

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