Quickload

[Spook]

Is anyone else finding that Quickload isnt getting real close with heavy bullets? Its been very hit and miss for me using 220+ gr projectiles.:frown:

[love2shoot]

while I am not using 300 whisper brass.....I am using 7.62x25brass running the same projectiles.......I have found so far that quick loads has been 15% to 25% off on predicted velocities on everything 180grns and up.

I am about to try the my next round of loading subs for this and am loading them for a higher quickloads velocity hoping to get them were I want them. I am also trying out some loads with standard primers and with magnum primers to see what the difference will be.....

I am loading for an estimated velocities from 1100FPS up to 1300FPS with most of this batch in anticipation of things running slower. Some powders may stay closerer to the predicted then others. from what I have seen and read. there is a LOT of expermintation and a learning curve for reloading the subs.......but when you get it, dam it is sweet.

[love2shoot]

guess I should kinda retract my statement after my day at the range.......

It seems it may be more of the powder used that can have that effect. Using W296 and Lil' gun powders QL is either right on or very close. 2400 and 3n38 was way off from QL.

[LouBoyd]

Quickload makes rough assumptions about barrel friction. You can set the value if you know it. Bore friction has a greater effect on subsonic loads since there is less propellant force.

Quickload makes rough assumptions about bullet engraving forces and their effect on pressure. Again, you can set the values if you know it. There is no input for bullet shape or leade angle. It does not have a setting for bullet jump to the lands. Subsonic loads are more sensiitive to engraving forces.

Quickload makes the assumption that the powder charge will be uniformly ignited and will burn normally. That may not be the case for low case fills or compressed loads. Quickload has no place to select primers or primer burn chacteristics. Subsonic loads often have low case fills.

Quickload has no provision for calculating blowby. When a heavy bullet is fired with fast powder the neck will expand to the chamber neck diameter allowing propellant gas to blow past the bullet and out the barrel if the bullet is not seated on the lands. In extreme cases all of the propellant will blow out and leave the bullet sitting unengraved in the chamber. I had that happen with a 240 SMK in a 300 whisper case with 5 grains of Bullseye in a Thompson Contender barrel with the bullet seated 0.15" off the lands. . Quickload predicted 1000 fps but the bullet never even engraved into the bore, yet less exited the barrel. I don't consider that the fault of quickload. I consider it an important learning experience.

There's a second form of blowby when an undersized bullet is used and propellant gas blows past the bullets along the rifling grooves. That too can have a large affect on predicted velocities, particularly for subsonic loads.

[BWE Firearms]

I just chronographed some loads I worked up on Quickload for my 50 THUMPER. With 21.5 gr. of H110 and 690 Gr. FMJ 50 BMG bullets Quickload said velocity should have been 990 FPS. Actual velocity averaged 825 FPS. I adjusted the Long barrel friction setting to get the program to display the correct velocity and we will chronograph those tomorrow. Keep your fingers crossed.