Max loads for short barrels ?

[Uncle Miltie]

I believe the Davenport Formula is a guide, and nothing more. Powder type, bullet weight, design, temper (hardness) patch thickness, material, lubricant and pressure applied while loading can all affect how powder burns. For basic roundball rifles up to target guns it is still up to the shooter to define the level of accuracy they are willing to accept and tailor their load accordingly.
This shows a slug rifle I shoot that is .56 caliber. 27 1/2" barrel loaded with a 977 grain paper patched bullet the usual load is 160 grains GOEX Cartridge powder. For distances past 500 yards I use 190 grains. I shoot for accuracy alone. If more powder increases accuracy then to me it is not a waste of powder.

 

[tenngun]

It ok to fear what you do not understand.

The davenport formula tell you the maximum powder that can be burnt in your length of barrel.
From there you work backwards to find the best groups charge.

My 45 cal, 42inch Rice barrel can not burn more than 74.5 grs the rest is wasted.
My most accurate groups are at 54.5 grain.
I use the 54.5 gr out to 100 yards, then use the max burn 74.5 grain for up to 150yardsm which is as far as I can see these days.
I was doubling the charge before 109gr, and wasting all the powder. That is what the Davenport Formula is for.

If you are blowing flame, you are wasting powder.

I don’t the formula, I’ve heard of it but never investigated it.
Looking at the Lyman ballistics that while there are diminishing returns there is an increase in velocity in .45s above 75 grains of three f
As I stated above down range higher velocities don’t always work out to better preformance
What exactly does it mean with this formula that that’s a top charge?

 

[deerstalkert]

I believe the Davenport Formula is a guide, and nothing more. Powder type, bullet weight, design, temper (hardness) patch thickness, material, lubricant and pressure applied while loading can all affect how powder burns. For basic roundball rifles up to target guns it is still up to the shooter to define the level of accuracy they are willing to accept and tailor their load accordingly.
This shows a slug rifle I shoot that is .56 caliber. 27 1/2" barrel loaded with a 977 grain paper patched bullet the usual load is 160 grains GOEX Cartridge powder. For distances past 500 yards I use 190 grains. I shoot for accuracy alone. If more powder increases accuracy then to me it is not a waste of powder.

 

[tenngun]

Yes Lyman found a 70 grain charge produced a MV of 1969 in a 43” barrel, 80-2206, 90 2237, and 100 2367
In a 28” barrel 70 at 1670, 100 at 2008
Down range tells a different story
At 2200 at fifty yards slows to 1615, a hundred 1226
1700 MV yields 1228 at fifty and 952 at a hundred a 27% advantage at the muzzle slows to 22% at fifty yards 19% at a hundred

 

[nhmoose]

Only a chronograph can answer. Real measurements beat wives' tale every time.