Been testing IMR-4759. No ignition problems.
Ignition is instant with regular primers.
Don't need Blue Dot starter powder.
Plastic cases first.600 gr slug. I got a
nice working roll crimper attachment
for drill press for crimping slugs.
That sure makes it easy, and perfect crimp.
In 2 & 3/4 plastic cases with loaded
length of about 2.35 inches got to 80gr.
That's max as you must leave room for
about 3/8 wads or cushion wad. Some cases
may only hold 75 grains max due to
the case construction.Powder is less dense
than RE-15. 1650 plus fps in 24 inch barrel.
In 3 inch cases, loaded length about 2.6
inches, got to 95 grs max, 1800 plus fps.
Some cases may only hold 90 gr due to
case construction. Cushion is
a half inch felt wad or equivalent.
Both lengths start down and go up
if pressures allow. 60 gr short case,70 long.
This powder being faster than RE-15 you must
have a little cushion in the way of felt wads
or plastic cushion wads.With slower RE-15
a card wad works ok as powder started slower.
The powder burning must build pressure
to open crimp with out a high pressure spike.
This bulky powder with reliable ignition
is a winner.Then we tested 3" Rocky Mtn brass
cases, Got max load of 105 gr, and 1900 plus
fps. In few weeks will get the 4759 and RE-15
loads pressure tested.Ed