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Old August 21, 2013, 10:54 PM   #1
Col. Mosby
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2F vs. 3F Load

I was wondering, if I was to load the same rifle with 70 grains by volume of 2F and then switch to a load of 70 grains by volume of 3F what would be the difference in pressure, muzzle velocity, and where the ball would hit on target using the same ball/patch combo. I would appreciate any thoughts on this subject.
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Old August 22, 2013, 06:32 AM   #2
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yes a little .
3 F produce a little more pressure .
what we used to do is when converting from 2F to 3 F we would reduce the 3F load by 10 grains . this should put you in the ball park of the Volocities and pressure of the 2F load when using 3F
when going from 3F to 2 F, we would increase the 2F load by 10 grains . thus bring the 2F load up close to the 3F charge .

IE lets say you use 80 grains of 2F . Then 3F load would be around 70 grains
If using 80 grains of 3F and going to 2F then the 2 F load would bump up to 90 grains .

As to how much difference you will see down range , that depends on the range .
Speaking for myself , the only thing I use 2F in anymore is my smoothbores .
I shoot 3F in all my rifles from 45-62 and even in a couple cases 3 F in my smoothbores when im shooting RB vs. a shot load
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Old August 22, 2013, 10:21 AM   #3
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Captchee, I thought the recommended split was to subtract 15 percent by volume.
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Old August 22, 2013, 10:41 AM   #4
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Never mention of a caliber? Knowing the caliber would indeed help Col. Mosby.
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Old August 22, 2013, 10:50 AM   #5
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For Sure !!!

The simple answer to your question, is yes and know a number of shooters that prefer the 3-F, and equal by volume. Regardless, you still have to put in some range time, in order to establish your optimum loads. ....

Be Safe !!!
'Fundamental truths' are easy to recognize because they are verified daily through simple observation and thus, require no testing.
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Old August 22, 2013, 03:07 PM   #6
Col. Mosby
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Thank you gentlemen for the imput.

Sure Shot, let's use .54 cal for an example. At say 25 and 50 yards, how much difference would there be in where the ball printed on paper. That is considering a ball/patch/powder combo had been determined for a particular rifle.

Captchee, I have great respect for your knowledge and craftsmanship. You may not remember but a few years ago I was having a problem with the lock on my Bess. I contacted you via a PM and you spent a lot of your time helping me out. I followed your advice and was able to fix the problem. That Bess is still working fine today! I have found that if you give advice one can "hang their hat on it". Thanks again.
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Old August 22, 2013, 03:34 PM   #7
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I think that the bullet drop is going to be determined by muzzle velocity, and that will be determined not only by the charge size but the barrel length.

Probably the easiest way to determine the answer is by experiment. Make up 10 cartridges with 3F and 10 with 2F and observe the difference.

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Old August 22, 2013, 04:01 PM   #8
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I thought the recommended split was to subtract 15 percent by volume.
Nope. The 15% reduction rule is for switching to 777 from real black powder.
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Old August 22, 2013, 05:28 PM   #9
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FF Black Powder will produce better accuracy in any caliber from 58 down to
and including 32 if accuracy is of any importance to you. is offline  
Old August 22, 2013, 05:29 PM   #10
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I have one possibly relevant data point.

I load 270gr RCBS-SAA bullets in 45 Colt with 35gr volume of 777 FFg and a lube cookie. I get about 800-810fps muzzle velocity.

Same load switching to 777 sized FFFg, I get 807-815fps muzzle, but the gun is noticeably hotter to the touch.

Enough hotter I started a thread in this section some time this summer looking for a caliber that likes FFFg; because in my experience 45 Colt ain't it.
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Old August 23, 2013, 06:35 AM   #11
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Captchee, I thought the recommended split was to subtract 15 percent by volume.
It depends on the Powder Roland .
Many year back , Sam Fedala put out a comparative pressure chart showing the pressures of black powder charges of 2and 3F , up to 120 grains if I recall . I still have one of his books somewhere with that chart in it

What that charge showed was that in order to get a 3F load down to the pressure of a 2F load , the shooter needed to reduce the charge by around 15 grains .
That reduction however is relative to barrel length. IE same gun , and powder make . The reason for that is that different barrel lengths produce different muzzle pressures for given powder charges
It Not however relative in velocities even in the same gun..
In other words , basically the projectile doesn’t care what you put down the barrel . All it cares is that it gets the pressure it needs to propel it to its most accurate velocity .
Now assuming that the shooter has put in the time and has an accurate load worked for 2F and then decides to try 3F , one would believe they also want the same performance down range that they had achieved with the 2 F load . What Sam’s chart showed was that by reducing the load by 15 grains , the charge would be just lower then the 2F charge in pressure . 10 grains would be just higher then the 2 F load in pressure .
I would have to look that difference up as the last time I looked at the chart was when we were working on your sharps carbine load
When it comes to powder makers , that reduction can be even greater . IE if your changing from elephant to Swiss which is greater then if your changing from Goex to Swiss .
But also remember that Sam’s data was based on powder that was being produced near 40 years ago.

when it comes to T7 . i do believe it calls for a reduction of 15 grains and Pyro a reduction of 10 grains in order to bring it into the pressure area of true black powder .
How accurate that is , I don’t know because I don’t use T7 and only use Pyro in my cartridge shotgun loads

as to whats more accurate 2F or 3f .
Myself I find that depends on the gun and what your trying to do with a load .
I have guns that producer much better results with 3F then they do with 2F . But I also have others that want completely the opposite .
Now with shot loads , most times I find 2F or even 1f “large bores “ to produce better patterns. So it just depends .
But as I said before , I have come to the point I use mostly 3F in everything I own .
Does that mean others will get the same results ,, no not really as its all about what works best for you and your situation .

Mosby .
im glad to hear your Bess is still working well for you and that I was able to help you through your issues .
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Old August 23, 2013, 09:38 AM   #12
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Captchee - the Hodgdon (powder manufacturer) recommendation for achieving equivalent performance with 777 compared to real black powder (regardless of brand) is to reduce the 777 load by 15 percent, not 15 grains.

As for switching between 2f and 3f with real black powder, using 15 grains regardless of the base charge doesn't seem right. I haven't seen Fadala's chart, but it seems to me that it would be more reasonable to use percent instead of a single absolute value for all charging levels. If your base charge is 30 grains/volume of 3f real black, reducing it to 15 grains/volume of 2f can't possibly give the same performance. Even at a base charge of 100 grains/volume 15 grains seems too high.
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Old August 23, 2013, 05:13 PM   #13
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again i dont know about T7 . as i said , i dont use it so ill have to lean to your numbers .

Im pretty sure Sams numbers are a 15 grain reduction , measured by volume .
The aception to that however is if one goes on velocity which is what Lyman IMO does .
So if we look at the 50 cal chart for a 28 inch barrel 1 in 48 twist ,shooting a RB backed with 90 grains of 2F, muzzle velocity is 1573 . Pressure 7000 ,ftlbs @100 is 396
If we look at the same set up but shooting 3F to get the FPS you have to drop to 70 grains to get close to those numbers
Which would seem to support your 30% or there abouts .
But if we look charts for the same caliber , but in a 30 inch barrel with a 1 in 60 twist we see that there is very little difference between the velocities of the two . IE 2F comes in at graduations1721 and 3F comes in at 1736 of powder for 90 grains . Ftlbs at 100 are also very close at 414 for 2F and 418 for 3F . But what does change is the pressure produced . 2 F is listed at 8000 while 3F is listed at 10,800 .

Now to complicate things even more . Those numbers are for elephant brand powder .
If we look at Goex then those same numbers are not so near .

This is one of the things about BP that often confounds the math . Simply put there is no ; if you do X you will get Y .
Myself I have looked at these issues more as a guideline or starting point . not as a set , black and white rule . doesn’t mater if its ballistics of the RB or black powder in and of itself . There are just to many variables to do say ; this is how it is .
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Old September 2, 2013, 12:59 PM   #14
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I have heard that the 3F is not as dirty as 2F.
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Old September 2, 2013, 02:12 PM   #15
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I have to agree with Captchee in that there are not necessarily any absolutes when it comes to the science of black powder loading. I know other people that use only 3f and seem to do very well with they know their firearms and what works best for them.
I personally use 3f for everything up to and including 50 Ca. and 2f for larger stuff including the smoothbores. I don't load to anything that would be considered a maximum load, so I have wiggle room to play with. Generally speaking, if I were to substitute 2f in a rifle with an equivalent volume of 3f, I would expect my point of impact to lower, as the 3f would give me higher velocity and get the ball out of the barrel quicker in the arc of recoil. This is a lot more evident with pistols as the shorter barrels raise more in recoil.
Within reason, if a pistol groups with the load, a person can adjust some of his elevation by just altering powder charge. In one of my favorite .40 Ca. pistols I can adjust elevation by about 2" @ 25 yds by using either my normal 20 gr. charge with a 35 gr. charge of 3f.
I have no doubt there will be others that disagree with my on these observations, but these things have worked for me for many years, and I have won a lot of competition with my techniques.
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Old September 4, 2013, 06:24 AM   #16
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I believe you should reduce based on percentage and not a fixed volume. Let's say you have a .32 target pistol that shoots very well with 10 grains of FFg, so you switch to FFFg, reducing the load by 10 grains is no powder charge whatsoever and we know that won't shoot. Reducing it by 10% would be a 9 grain charge, and will probably shoot well, much better than a 10 grain reduction would.

A 10 or 15 grain reduction rule of thumb only works in a limited domain, that of rifles with bores that normally use FFg as a main charge.
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Old September 4, 2013, 09:19 AM   #17
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Well answered by many and even overanswered, except for the statement:
FF Black Powder will produce better accuracy in any caliber from 58 down
Which is an opinion of some but not universally.
I use only 3Fg in all calibers. Shoots cleaner and requires a little bit less powder.
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