Is there a way to convert different powder grains?

[Onojutta]

Over the years I have accumulated various sizes of blackpowder and have on hand containers of FFFF, FFF, and FF. As some barrel manufacturers like Rice specify to use no smaller than F or FF, I am wondering if there is a way to convert grains of one size to grains of another should I ever find myself in a SHTF scenario, have to resort to my longrifle for survival, and run out of FF.

For example, if the max load for my rifle is 80 grains of FF, is there a way to determine an equivalent smaller load (volume) of FFF or FFFF? Realizing this would affect accuracy, the chief concern is not marksmanship, but being able to simply fire the rifle safely without causing damage to the barrel.

 

[bang]

Volume is volume. 1f burns a tad slower than 2f burns a tad slower than 3f all of which can be measured in plank moment time. 4f primarily pan primer and firecrackers.
Velocity and pressure might go up some using smaller grain. But slightly.

 

[Grenadier1758]

The closest conversion that we use is drop the volumetric load by 10% as you decrease grain size. A load of 80 grain volume of FFg will be matched pretty closely by a load of 70 to 75 grains volume of FFFg. The FFFFg probably should be limited to use as priming powder or in small quantity loads in a 36 caliber or smaller rifle or in a cap and ball revolver.

 

[Eterry]

Lyman's Blackpowder Manual. Using chronographs and pressure gauges determined you could use up to 40% less fffg compared to ffg and get similar velocity and pressure.
I guess i'm the only one whose read that.

Years ago before there was an internet to tell me it was wrong I shot a full pound of ffffg in my 45 CVA. I had no problems at all.

 

[hanshi]

Either 3F or 2F will work without a hitch. Go for an accurate load and you'll be quite safe.

 

[tenngun]

You can test your loads, 1F was used in the past, and powder came in the old days as musket, rifle,pistol powders.
ITHINK they tended to larger in the old days, we have easy access to chronograph and chronograph info today, and like them fancy numbers.
People often had powder testers in the old days and adjusted charges as needed. Trying for one hundred ten x at a hundred yards it can make a difference, turning Bambi French won’t make a difference what powder you have.

 

[Grenadier1758]

Lyman's Blackpowder Manual. Using chronographs and pressure gauges determined you could use up to 40% less fffg compared to ffg and get similar velocity and pressure.
I guess i'm the only one whose read that.

Years ago before there was an internet to tell me it was wrong I shot a full pound of ffffg in my 45 CVA. I had no problems at all.

No, you're not. I have some questions about the results in the 1974 Lyman manual. Some of the results just don't seem correct. Pressure and velocities just didn't add up. What you read is one of those charts that I question.

 

[Eterry]

I guess i'm lazy, I have a Pact Chronograph and it would be easy to test fffg vs ffg, but I haven't.

I know a lot of N-SSA Skirmishers use fffg, and lower their charges 30-40%.
Of course it don't take a lot of velocity to break a clay pigeon.

I know Lyman's data is somewhat dated, but many man hours, lead and powder was used to put the manual together. I haven't seen any data that contradicts Lymans data on the whole.

I have about a dozen smokeless powder manuals and none of them are 100% in agreement.

If anyone knows of a newer black powder manual I'd like to know about it.

 

[Hatman/2nd line]

Lyman's Blackpowder Manual. Using chronographs and pressure gauges determined you could use up to 40% less fffg compared to ffg and get similar velocity and pressure.
I guess i'm the only one whose read that.

Years ago before there was an internet to tell me it was wrong I shot a full pound of ffffg in my 45 CVA. I had no problems at all.

Do you remember what amount you used with 4f for your .45?

 

[Eterry]

Do you remember what amount you used with 4f for your .45?

IIRC, I used 50 and 60 grs of ffffg. I was about 19, didn't own the Lyman Black Powder Manual and had no guidance.

The important part is I had no issues, and I could shoot longer without swabbing or cleaning the bore. I wouldn't have a problem using it again based on my past experiences.

 

[Hatman/2nd line]

IIRC, I used 50 and 60 grs of ffffg. I was about 19, didn't own the Lyman Black Powder Manual and had no guidance.

The important part is I had no issues, and I could shoot longer without swabbing or cleaning the bore. I wouldn't have a problem using it again based on my past experiences.

I had a chance to buy a lb. of 4f the other day and passed it up! I could have used it!

 

[Widows Son]

Years ago before there was an internet to tell me it was wrong I shot a full pound of ffffg in my 45 CVA. I had no problems at all.

How did we all survive back then?

 

[Woody Morgan]

How did we all survive back then?

Many didn't.

wm

 

[dave951]

Ok here's the skinny.

Volume is volume BUT, what gets put into it may or may not pack it out to the same amount of mass. SO, 50g by WEIGHT of 2f takes up more volume than an equal WEIGHT 3f due to the larger grain size. This means if you switch from 2f to 3f and are measuring by VOLUME there's be more powder in the charge.

Therefore, if you're going to switch from 2f to 3f, cut the charge about 10% for a starting point. If going from 3f to 2f, use the same volume and work from there.

Now most here will drone on about using volume as the only method of measurement for the holy black but, a serious competition shooter will nearly always work up his load based on WEIGHT and set his powder measure accordingly. Reason is the nature of the structure of individual powder grains lead to errors in the mass of the charge which can lead to differing chamber pressures which means loss of accuracy. For best accuracy, control of variables is the name of the game and weight variations of the charge is just one of many.

 

[Loyalist Dave]

Reason is the nature of the structure of individual powder grains lead to errors in the mass of the charge which can lead to differing chamber pressures which means loss of accuracy.

Yes not to mention that it's been found that depending on the company (or the person) who made the measure..., that too can cause problems with the actual weight in grains. What I mean is, if the shooter finds X brand of powder measure set at 75, gives really consistent loads of 75 gr of 3Fg, and then uses a different measure from a different company, that same setting can be off. HECK you could've bought a powder measure in 2000, and replaced it with the same brand last year and find "Uh Oh..., the new one looks a total duplicate but it's throwing a different charge."

It seems that the OTC powder measures are meant for hunters, not target shooters. So for folks shooting out to 50 yards the varying loads may not really show. From 50-100 they may show a bit, but as far as the deer is concerned, dead is dead. So the hunters don't care, the powder measure works "just fine".

But for folks reaching past 100 yards or to whom the difference in a 9 score vs. a 10, or an X, that stuff can mean a whole lot.

LD

 

[Grenadier1758]

I do know that my various volume measures when set at the same grain weight will result in different measures when I pour the same powder into the measures and weigh them on my weight scale. Differences are perhaps only a few grains. I do know that when I weigh several volume measures the differences between loads is small. Standard deviations of less than a grain.

When working up a target load, always use the same measure and same pouring procedure.

As far as converting between the different grain sizes, the old rule of thumb, at least when you stay within the same brand of powder, use 10% less powder when going to a smaller grain size. If the load is 80 grains of GOEX 2fg, then a load of 70 to 75 grains of GOEX 3fg would have similar performance.

 

[Eddie Southgate]

If in a real SHTF situation you wont have time to worry about grain size , just use what you got . I prefer FG or FFG in my .58 musket but I have shot a manure ton of FFFG in it and never had any trouble because of the grain size . The FFFFG I would use in a revolver if push come to shove but it of course would not be my first choice, but it would work just the same .