With BP, have been using a B&M and then weighing each load on my digital scale and trickling up to the wanted weight before pouring through the drop tube into the case. Am wondering if one can simply 'throw' the load using the B&M (or Lyman #55 or other powder dispenser) and weigh every 10th throw, or so (like with smokeless) and still have accurate fixed ammo? The B&M seems to vary about 0.3gr with Goex FFg.

+1 - if that's all the variation you're getting, you won't even be able to see any difference in accuracy on target, even at 1,000....  Just keep it simple.

Throw with the B&M  Some times I will weigh just to prove to myself I only need to throw.  I suspect the spring loaded lever in the B&M takes the most common potential error out, operator error with inconsistent lever operation. My 55 is not as reliable in operation as the B&M, it can be short stroked with resulting slack charge. 

However when weighing I set the measure to throw the exact charge and  check weigh. Most times every 10th charge but if not sure every charge.

Although it's often recommended in manuals and by the people who sell dribblers never could see the logic in throwing light and dribbling up. Might as well just throw the right charge and use the scale to confirm it's correct.

Boats

Schuetzendave wrote on Sep 16^th, 2011 at 2:14am:



Dave, why do you think theres a sweet spot at .3 grains and not at .4 grains?   

Does this happen with all barrels? 

Will my barrel have a sweet spot at .3 also?   

             Joe. 

     

"Does this happen with all barrels?"


Joe:

I have been custom loading for a number of shooters for numerous years and have recorded the group sizes by one tenth grain loads.
Generally the sweet spot is .25 to .3 grains apart regardless of action or powder or barrel manufacturer.

I have tested Sakos, Tikkas, Winchester Model 70, Remington 700, Mausers, BSA Martini, Martini Henry, Kimbers, Coopers, Browning A-Bolts, Rugers, CZ Ceska Bruno, Millers DeHaas, Yost, Stevens 44, Stevens 44 1/2, Savage 200, Winchester 1885 HighWalls in a variety of calibers with factory barrels or with custom RKS, Douglas, Lija, or Half Moon barrels.

I have tested mostly all of the Hogdgon powders, some IMR, Accurate Arms and Reloder powders. For black powder I have tested with Elephant FFg, Goex FFg, Goex FFFg, Swiss 1 1/2, Swiss 2, Swiss 3 and Graf & Sons FFFg.

Paul Short family happy with the sweet spot I custom loaded for the .300 Winchester Magnum on a Sako L61. This rifle would shoot five shot groups of 0.2 MOA consistently.

"Why is there a sweet spot at .3 grain intervals ? Why is it .3 and not .4 or .5 or some other number?" 

Joe I do not know why the sweet spot is at .3 grains. That is the number that keeps coming up from my testing over the years.

I assume the powder variations at .3 grain intervals is in tune with minimal barrel vibration at that powder load interval.

Not my experience - but then I use the incremantal charge method.  any load that requires to be weighed to 0.1grs is not reliable - accuracy will vary with temp, humidity etc.

Whith the incremental charge method, it is possible to determine a sweet spot where even a few tenths won't make an appreciable difference - making for a much more reliable load, regardless of conditions.
also, the man is asking about BP - not smokeless.  That variation with BP won't even show up on the chrony...