FFFg equivalent to FFg

[e.estern]

The .45 cal percussion rifle I'm working with produces good results with 60gr of FFg, but I'm wondering, is there a way to guesstimate how much FFFg would produce similar pressure? Seems like many shooters prefer FFFg in the .45.

 

[ord sgt]

I use 40-50 grains FFFg in my T/C and get good results for target shooting. The difference in grains of powder depends on my mood that particular day. Both seem to work well.

 

[Johnny Tremain]

Use the Davenport Formula (found here somewhere) find the maximum 3f change you can burn, then work backwards for accuracy.
My 45 cal has a 42 inch barrel, the max I can burn is 74.5 grains. My best shooting is with 54.5 grains.

 

[rafterob]

Seems that 5% reduction has been offered up here before.

 

[springfield art]

(Joke) Or, you can glue two grains together to make larger "F's"! Repeat several thousand times!

 

[maillemaker]

Typically you can use 5%-10% less 3F than a charge of 2F and get similar ballistic performance.

But not always. Sometimes 3F gives such a quick pressure spike it causes the bullet to engage the rifling differently, or perhaps the bullet deforms differently. Sometimes a gun will prefer 2F.

 

[Surrywoodman]

I have been told in the past that it was roughly a 10% differential, so in my 50s I have found 70gr of FFG to be a good load, and I have been using 63gr of FFFG and getting the same results (as far a grouping goes) with PRB, I am sure I could dial in further and optimize the loads better but I have not as yet done so

 

[hanshi]

I never tried reducing the 3F loads but rather increased the 2F on those occasions when I didn't use the same powder charge with both. FFFg has always been my default powder and used in any and all calibers for the most part.

 

[maillemaker]

There is a great article in the September Muzzle Blasts NMLRA magazine about the differences between granulations, including information on recoil and measured velocity using the same charge of 1F, 2F, and 3F.

 

[Rifleman1776]

Don't overthink this with "formulas", etc. Just try it and see the results. Same volume might affect serious 'X' shooting accuracy but really have no noticeable effect for primitive events or hunting.

 

[Loyalist Dave]

Don't overthink this with "formulas", etc. Just try it and see the results. Same volume might affect serious 'X' shooting accuracy but really have no noticeable effect for primitive events or hunting.

Yes..., in theory using the 3Fg in place of your 2Fg load, and the same volume, you should get results akin to having increased your 2Fg load to 65-70 grains. It might change your point of impact, higher, at 100 yards, and at 50 yards may not be noticed. The deer may not know they are any deader, either.

LD

 

[e.estern]

I’ll hopefully try it today, maybe back off 5 grains from my 2F charge for starters.

 

[user 48679]

FWIW, I've been hunting with my 27" bbl .45 Seneca for a long time (over 30 years), loading 70gr FFFg under a T/C MaxiHunter conical, without any issues.

 

[e.estern]

Yes this is for a Seneca, which is why I'm being cautious with the load development.

 

[45man]

I have test results using FFG that gives an average velocity of 1256 fps and the same amount of FFFG raises that to 1340 fps. Not a great difference but groups changed depending on the rate of twist. Goex.
Swiss raised the velocity with FFG giving 1396 and FFFG with 1414 fps.

 

[Ben Meyer]

With my .50 flintlock, 80gr of 2f and 70gr of 3f Swiss hit in just about the same spot.

 

[Tenring]

There are different burning pressure rates between 2F and 3F that’s it. Your shot may be a little high due to higher pressure burn rate.

 

[hanshi]

So far my only shooting with Swiss (3F) was in small calibers, .32, .36. Haven't chronographed, which I need to do, these loads but I'd expect the velocity with Swiss to be a bit higher than Goex.

 

[Tenring]

Very true Swiss is a more refined powder that has a lot of get up and go.

 

[tenngun]

I have been told in the past that it was roughly a 10% differential, so in my 50s I have found 70gr of FFG to be a good load, and I have been using 63gr of FFFG and getting the same results (as far a grouping goes) with PRB, I am sure I could dial in further and optimize the loads better but I have not as yet done so

I can shoot 65 grains of three f in my TFC or Eighty grains of 2f and I can’t tell shooting difference then